Cosmetic Dentistry : The Mayan Style

Mayan area   
Courtesy Simon Burchell, wikipedia 

Mayan civilization  flourished   in and around Yucatan peninsula in Central America for almost 3000 years.    It reached  glorious heights during AD 200-800. . Thereafter  it declined,  for   reasons  not clearly known.  Sudden climatic changes, earthquakes  or even epidemics could have triggered the decline.  Investigations are still ongoing and speculations are innumerable.    Archaeological excavations are being  conducted in several parts of the Yucatan and have yielded rich artefacts which are being subjected to scientific scrutiny.  The colourful collage that results from joining together the details derived from  historic artefacts and ecofacts  is simply awesome.  Thus we know that   Mayans lived in well organised city-states; they were a farming society  cultivating maize, cacoa, cotton etc.;  they wore elaborate headdresses adorned with colourful plumes; they had a pictorial  writing system and  a counting system  based on 20; they had extensive knowledge of herbal medicines. Above all they had drawn up calendars based on the movement of celestial bodies. It is often said that the  Temple of Kulkulcan   at Chichen Itza   was built taking into consideration  the sun’s location during the spring and autumn equinoxes. 

Artistic representation of the Mayan bejewelled teeth 
 in National Museum of Mexico 

Among the artefacts preserved in the Mexico city National Museum,   are skulls dating back to AD 700.  In many  of these skulls, labial teeth  are adorned with  inlays of gold or embedded with  precious stones.  These adornments could have  aesthetic/magical /religious  connotations.  That apart,  scientists  are  amazed at the exquisite craftsmanship. It is indeed astounding  how  shallow cavities are carved out on tooth surfaces  neatly and skilfully using primitive tools. Obviously the craftsmen had an excellent knowledge of dental anatomy. 

Even more surprising is the glue or cement that holds the gems in place.  What  miracle  glue did the Mayans use, that even after  centuries  some of these gems are held firmly  in place ?  An earlier

Courtesy: Reference 1

 analysis yielded information that the cement  contained large amounts of  phosphorous and calcium, with smaller amounts of iron, silicon and  magnesium.   Recently    Hernandez-Bolio and team studied  skeletal artefacts  excavated from      sites such  as  Holmul (Guatemala), Baking Pot (Belize), and the Copan Valley (Honduras).      They used  modern techniques  such as    Attenuated Total Reflectance Infrared Spectroscopy (ATR-FTIR) and Gas Chromatography coupled to Mass Spectrometry (GC–MS).  Eight dental specimens when subjected to these techniques revealed that the glue contained, pine resin and bitumen mixed with  extracts from the plants of  mint family. 

Primary biological role of these terpenoid  oleoresins,   exuded by trees like pine is to defend  against insects and pathogens. The Investigators  allude that  the  antibacterial and anti-inflammatory properties of these oleoresins  might have contributed to dental healing and  oral hygiene.  

More about oleoresins later

TAILPIECE:

The full compositional analysis of the cement/glue is yet to be completed.  Then there are other nagging  questions  seeking answers. What were the primitive tools used? Given that Mayans knew about intoxicating and hallucinating drugs, did they use any  herbal medicines as local anaesthetic  or a sedative ? 

REFERENCE

1.  Organic compositional analysis of ancient maya tooth sealants and fillings:  Hernández-Bolio  et al Journal of Archaeological Science: Reports  Volume 43, June 2022, 103435

2. 

Of Pests and Pest Management

Potato traces its origin to  the Andes, in South America.   Centuries ago, the humble crop crossed the Atlantic sea and reached Europe. Since then it  has travelled far and wide and has become ubiquitous. It is now  an indispensable   component in most of the  cuisines.  Easy to grow, this staple food  is  cultivated all over the world.  However  potato plants  have  an  alarmingly, powerful enemy:   the parasite Potato Cyst Nematode (PCN). The juvenile worms of PCN cling the potato sapling's tender roots and suck out  all the nutrients  causing the plant to wither and wilt. This has devastating effect on  the crop  yield.  Upto  80% reduction of the yield, and at times total crop loss  have been reported. 

PCN  cysts ( in yellow ) clinging to potato roots:
Courtesy: wikipedia 

PCNs  belong to the Globodera genus. These are  a class of obnoxious yet  very smart plant pests. These nematodes or roundworms  infest plants in the solanaceous family such as potatoes, tomatoes and eggplant.  Interestingly Globodera also trace their origins to the Andes, in South America. Definitely a case of coevolution.

PCNs come in male and female forms.   Once fertilised, the female dies, its bodily remains forming a protective hard cover  around the eggs. A single such cyst could contain upto 500 eggs suspended  in a thick viscous sugar syrup.    The  sugar is  trehalose, which  is a dimer of glucose.   The hard outer shell and the viscous syrup inside  jointly protect the eggs  from  all kinds of mechanical stress and preserve them intact for decades. The sugar also serves as an energy source. Thus  the cysts lie in wait patiently for  a signal  to hatch.   

Courtesy: Shenk et al 

That  the signal comes from the roots of plants belonging to the  Solanaceae family,  was known as far back as in 1923.  The tender roots of potato  exude a mixture of  chemicals. One of the chemicals, later  identified as  Solanoeclepin A  is a stimulant for  hatching  the PCN eggs.   This chemical, a terpene,  with the  formula  C27H30O9  has an equally  complex structure. The structure was elucidated in 1999  by   Schenk et al.

Solanoeclepin A  initiates a series of activities  both on the  outside and  inside of the PCN  cyst. First, solanoeclepin A induces  the  cyst  wall to become a bit leaky. This causes  trehalose  syrup to ooze out and water/moisture to  rush in, thus irrigating the eggs and  facilitating their hatching.  However as a part of survival strategy, all of the eggs are not hatched in one go.   Professor Benjamin Mimee  and his team point out that  this could be   to increase population persistence throughout growing seasons and to lower competition between hatched juveniles.

Though pesticides  are effective, poorer nations find it unaffordable. This where  the  efforts  of a  global team of scientists with Professors  Danny Coyne, Charles Opperman and  Baldwyn Torto  at   the helm prove valuable.  Collectively  they have hit upon a simple strategy:  wrap the potatoes  in banana  paper  and then  plant. The banana paper  absorbs most of the  exudates,  including solanoclepin A,   thus   preventing hatching signals reaching the PCN cyst.  One  of the rare instances of  humans  vetoing Nature in very simple terms. 

REFERENCES:

1. Analysis of survival and hatching transcriptomes from potato cyst nematodes, Globodera rostochiensis and G. pallida

2. Elucidation of the Structure of Solanoeclepin A, a Natural Hatching Factor of Potato and Tomato Cyst Nematodes, by Single-crystal X-ray Diffraction*

3. Wrap-and-plant technology to manage sustainably potato cyst nematodes in East Africa

COVID Vaccine Stories III: The Inequity Factor

By now all (scientists included) are  resigned to the fact  that  COVID-19  is here to stay  and  that we must learn to live with it.  We may not be able to eradicate SARS-CoV-2 as we did smallpox and polio.   The  pandemic might eventually shrink to an endemic state which  can be easily managed with vaccines. That again is a fervent hope. As of now the focus is to get  everyone doubly vaccinated  as fast  as possible.     

That a large percentage of global population is yet to be vaccinated,  adds to the worry. This  began as  an economic issue.  The Rich  and the Powerful nations competed  with each other to procure vaccine supplies for their citizens.  They  hijacked  enough and more supplies  while the poorer nations remained helpless, mute bystanders. It took  time for the Rich to realise  that unvaccinated  populations are fertile grounds for  new variants.  In other words nobody is safe unless everybody is vaccinated.  

Courtesy:wikipedia

Vaccinating entire global population is a daunting task indeed.  Even  if adequate amounts of vaccines are  made available, as is the case  now,  logistics of  the supplies reaching every remote corner before the expiry date remains a challenge. Most of the developing nations do have very  robust healthcare  networks in place while most of the underdeveloped  nations don't.  With the result that  as of 14th February  2022, though  globally 10.4 billion doses have been administered,  80% of African  population remains unvaccinated.   

Coronavirus will  continue  to mutate,  at times  in unpredictable ways.  Still, the  fact that there are several vaccines already in the market and many more in the pipeline  is certainly "a cause  for  hope  and optimism"  as  Nature Magazine summed up  in its  recent  Editorial:    "but with  a hefty dose of realism: the virus  will continue to circulate  and change, and governments must continue to rely on the guidance and advice  of scientists. We will not always be able to predict the virus's  path but we must be ready to adapt  with it."

REFERENCES

1. COVID-19 will continue but the end of the pandemic is near

2. No one is safe from COVID-19 until everyone is safe.

3. Tracking Coronavirus Vaccinations Around the World

4. Dear G20 leaders: Vaccine equity is a must for Africa

5. Coronavirus  is here to stay

6. COVID is here to stay: countries must decide how to adapt

7. Achieving COVID-19 vaccine equity means overcoming hesitancy

Covid-19 Vaccine Stories: II: The Inimitable Cuban Style

When Covid-19 struck, Cuba knew it will have to fight alone, because the sixty year old economic embargo by the mighty United States  prevented Cuba's access to US vaccines.  Undeterred the scientists at the Finlay Institute of Vaccines,  together with the Centre for Genetic  Engg. and Biotechnology Havana rose to the occasion.   In May 2021,  The Guardian prophesied that Cuba could become  the smallest country in the world to develop its own coronavirus vaccines. In spite of economic hardships,  the country  surged ahead. The prophesy  came  true.  Cuban Vaccines  Soberana 02 and Abdala registered +90% efficacy against Covid-19. Today more than 80% of Cuba's 11million population stands vaccinated  and    scientists  are  tweeking  Soberana-02 to meet the challenge of the Omicron variant.

In Spanish Soberana means Sovereign and Abdala is a famous Cuban patriotic poem. The Mambuses are patriotic Cuban soldiers who  have always fought for Cuba

Sobarina 02 is the first conjugate vaccine to be developed against SARS-CoV-2.   In conjugate vaccine technology, individual components elicit feeble immune response, but together they are  very powerful.  Soberana-02 contains  a fragment  of the viral spike protein of SARS-CoV-2 chemically linked to an harmless  piece of a protein snipped from tetanus toxin. These two fragments linked  in  a molar ratio of 6:1 is  adsorbed onto  alumina and suspended in an appropriate medium.  Abdla, developed by Centre for Genetic Engineering and Biotechnology,

Centre for Genetic Engg.and Biotechnology,
Havana, Cuba

Havana,   is simpler,   a different   fragment of the spike protein adsorbed onto aluminium hydroxide and suspended in suitable medium.  Such protein vaccines  do not require extreme refrigeration  and are cheap and easy to  manufacture. There are several other candidates in the Cuban pipeline including a nasal vaccine  Mambisa.

In Spanish Soberana means Sovereign and Abdala is a famous Cuban patriotic drama. The Mambises are those patriotic Cuban  soldiers who defended Cuba on several occasions.

In the meanwhile Cuba has embarked on vaccine diplomacy by exporting Soberana-02   and Abdala  to Venezuela,  Nicargua, Iran and Vietnam. It would like to extend this gesture of comraderie  to less privileged nations who are in dire need of the vaccine. For this World Health Organisation's has to give the nod.

Tailpiece

“Cubans either don’t meet the mark – or go way past it.”

(Words of General Máximo Gómez, a key figure in Cuba’s 19th-century wars of independence against Spain : Guardian  5th Jan. 2022)

REFERENCES

1. Cuba punches above its weight to develop its own Covid vaccines

2.Cuba soars to near top of COVID vaccination charts on decades-old bet

3. In world first, Cuba starts COVID-19 vaccine for toddlers

4. Cuba's bet on home-grown Covid Vaccines is paying off

COVID-19 Vaccine Stories I : Modern(a) Twists

The whole  World applauded when a unique  Public-Private Partnership  was forged.  The   US Governmental agency,  National Institutes of Health (NIH) and  Moderna the  American pharmaceutical company    joined forces   to confront the  COVID-19 pandemic. They began with a shared vision: to come up with a vaccine  against the deadly virus in the shortest time possible. The two have been in partnership for about 4  years in matters of health.  Everything went on as planned.  National Institute of Allergy and infectious Diseases  (NIAID)  under the umbrella of NIH readily shared their laboratory findings with Moderna and then  Lo and behold!    a vaccine  mRNA 1273 or Spikevax  was in the market in record time. 

Moderna Covid-19 Vaccine 
Courtesy: wikipedia

NIH put out a report    that "The incidence of symptomatic COVID-19 was thus 94.1% lower in participants who received mRNA-1273 compared to those receiving placebo........... The FDA  issued an Emergency Use Authorisation  for Moderna to make the vaccine available for the prevention of COVID-19 in adults on December 18, 2020."  Peer reviewed  results  appeared in the prestigious New England Journal of Medicine in Dec. 2020.   In May 2021, Biden administration even hinted at  waving patent protection on humanitarian grounds. Rachel Cohen,  director for the non-profit Drugs and Neglected Diseases initiative in New York City Cohen is reported to have said : “These vaccines are an unparalleled triumph for science, but if only 20% or 30% of the world winds up benefiting, what is the point of the innovation?”

This must have been the  point at which  relationship turned sour,  the distaste spilling out in the open.  Moderna went  ahead and filed  core patents  omitting the names of the NIAID  scientists.  This makes Moderna  sole owner of intellectual property and sole beneficiary of  the profits reaped  from sales.   Anthony  Fauci, Director of NIAID is emphatic that names of NIAID scientists should have been included as inventors in the patent application   because it was a collaborative work.  Moreover   Moderna had received to the tune of 1.4billion dollars of government funding ( tax payers' money) to develop and test the vaccine.  However  CEO of Moderna  claims, that his scientists independently  invented the particular mRNA sequence used in the  vaccine. While NIAID argue they have already  published similar results much earlier in 2017(see Ref.2).  

It appears that Moderna extended consolation  arm to NIH by offering  co-ownership. But legal experts say co-ownership and co-inventor status are not equivalent. There is much more in fine print for co-ownership.

Moderna Headquarters,
Cambridge, Massachusetts
Courtesy: wikipedia

Moderna was founded as ModeRNA Therapeutics  in  2010.    The name implies modified RNA  the focus of the  company. For Moderna it makes business sense   to have full and exclusive ownership on the patent because the  COVID-19 vaccine market is expected to be   $19.5 billion in another 5 years.  Add to  this the fact that   Moderna's product menu has only one item:.  COVID-19 vaccine.

Tailpiece:

Reliefweb states: "Moderna’s Q3 profit before tax for 9 months ending September 30 is $7.8 billion on $11.2 billion revenue giving a pre-tax profit margin of 70 percent. The company projects full year 2021 sales to be “between $15 billion and $18 billion”. Using the lower end of the estimate —70 percent of $15 billion is $10.5 billion in profit for 2021. The vaccine is Moderna’s only commercial product."

REFERENCES:

1. Experimental Coronavirus vaccine highly effective

2. Immunogenicity and structures of a rationally designed prefusion MERS-CoV spike antigen:  Jesper Pallesen et al (PNAS Aug 19, 2017)

3. What the Moderna–NIH COVID vaccine patent fight means for research

4. COVID-19 vaccine market set to touch $19.5bn by 2026

5. In shock move, US backs waiving patents on COVID vaccines

6. Covid-19: Moderna seeks to exclude US government scientists from vaccine patents, despite public investment

7. Moderna, escalating dispute with NIH, claims government had no role in key vaccine patent

8. Pfizer, BioNTech and Moderna making $1,000 profit every second while world’s poorest countries remain largely unvaccinated

Time concrete turned Green

Obviously  the  concern is about the carbon footprint of concrete. According to a recent report, the annual global  usage of concrete is roughly 30 billion tonnes.  Going by the current trend,  this will rise  upwardly  for decades to come.    Concrete,  an aqueous   slurry  of cement, sand and gravel  can be poured  and  set  in any form.   Once set, the product has enormous strength, stability and durability with absolutely no maintenance cost.   Over centuries concrete has inspired and dared  architects and builders to dream big and build big. 

Burj Khalifa, Dubai

Concrete is 10-15% cement, 15-20% water and the rest an aggregate of gravel and sand. To get high quality concrete, water  to cement ratio must be kept low without compromising the workability of the mixture.  The ingredients are  mixed, set and cured  at room temperature. Seems like a very benign process. So what exactly is our quarrel  with  concrete?  Well our  issue is  not with concrete per se  but with the  cement in the formulation.  Cement is made by the calcination   limestone with clay at 1450 deg.C. This high temperature is achieved using fossil fuel, usually coal which holds a heavily  tarnished environmental  record.  During  the  calcination process multiple reactions take place in sequential  and parallel fashion. First of all  limestone which  is calcium carbonate,  releases  carbon dioxide  and becomes   calcium oxide  and  reacts with  oxides and silicates of  aluminium and iron   in the clay.   The resultant product  is  cement,  a complex mixture of  tricalcium silicate (3CaO · SiO2), dicalcium silicate (2CaO · SiO2), tricalcium aluminate (3CaO · Al2O3), and a tetra-calcium aluminoferrite (4CaO · Al2O3Fe2O3) with small amounts of gypsum (CaSO4 ).  This mixture called clinker  is enhanced with additives if needed and then  pulvarized to yield cement. This is the conventional cement  usually referred to as Portland cement.

Thus cement manufacturing is one of the most energy intensive  industries.  It is one of the highest consumers of fossil fuels.  Approximately   3 GJ of thermal energy and 110 kWh of electrical energy are needed to produce 1 tonne of cement.    In terms of  CO2 emissions  too the cement industry tops the list  with   600 kilograms of carbon dioxide  released into the atmosphere for every  tonne of cement manufactured .  And that  indeed  is our concern. 

We  cannot simply wish away the use of fossil fuels and switch to alternate/renewable energy . Simply because the cost factors are not   yet favourable.  Besides  Coal industries  are  the biggest  employment generators.    There are enormous  hurdles along this  path  because  globally fossil fuels are subsidised at two levels: production level and consumption level both of which  keep the cost to the consumer low.  A recent report in Nature (ref.2) states that  subsidies worth an average of US$555 billion each year were given  from 2017 to 2019.  The figure dropped  $345 billion in 2020 only because of lower fuel consumption and declining fuel prices during the COVID-19 pandemic. But can  the subsidies be withdrawn all  of a sudden?  The answer is No.  Among other factors, rising fossil fuel prices  will be extremely hard on people  in  developing and under-developed countries.     Political  parties and  governments may not want to even tilt the applecart. Along with drastic changes in  political and societal   mindset, cost effective   alternate energy sources must be made available. COP26 in Glasgow is debating this aspect and whole world is listening.

Another question  pops up here : do we have  alternatives for limestone? Perhaps we do. Fly ash, the residue from the coal plants is a possible candidate and so is  slag from the iron and steel industry.  Fly ash is the fine residue  after the combustion of coal   while slag is the residue from iron blast furnaces. Both contain  oxides of silicon, aluminum, iron and calcium and hence  bear an overall chemical resemblance to Portland  cement but not in precise composition or structure.  Nevertheless studies have shown  that  blending  conventional  cement with 20% of either  fly ash or  slag doesn't adversely affect the properties of the final concrete.  Currently blended  cement formulations with varying fly ash/slag  content are available in the market. However here is the catch:   with  a global consensus shaping up to phase out  coal by 2070,  future  availability of fly ash will eventually be an issue.   Slag has its own disadvantages regarding workability,permeability  and durability  which are being looked into.

Tailpiece:

Burj Khalifa :  Having consumed 110,000 tonnes of concrete,  Burj Khalifa, currently the tallest building on Earth, is guilty of releasing  660,000,00 kilograms of  carbon dioxide  into our atmosphere.  The environmental cost factor  of a total of 55,000 tonnes of steel and 103,000 square metres of glass  remains to be calculated.  

References:

1. Concrete needs to lose its colossal carbon footprint: Nature,30 Sept.2021

2. Why fossil fuel subsidies are so hard to kill?

3. Zimmer, M., Kuhanathan, A. & Badre, A. Abolishing Fuel Subsidies in a Green and Just Transition (Allianz, 2021).

4. Agenda for CoP26: Why phasing out coal will not be decided in a jiffy?

4.Optimizing-the-use-of-fly-ash-concrete.pdf

5. Sag Cement Organisation

6. Sustainable cement: the simple switch that could massively cut global carbon emissions

7.

GoodFood4All

Since the 1960's Prof Paul Ehrlich  has been  cautioning us  that  sustainable population for  Earth  is in the range of 1.5-2.0 billion. That was the world population  way back in the 1930's.  Whether Prof.Ehrlich's assumption is justifiable or not, not even in our wildest dreams  a  reset  to that number is possible.   United Nations'  Worldometer  shows that  as of Sept. 2021  we stand at  7.9 billion. The  UN study group on population furthermore   forecasts that  population  will peak at 11 billion by 2100 before a downward trend sets in.  There are other schools  who predict  that the peak will be at  9.7 million in 2060's  and thereafter it will begin to  decline.  Developing nations  will be registering  maximum growth,  sub-Saharan Africa topping the list with  +114% and  East/Southeast Asia tailing at  13%. Whichever way one looks at it, the challenge  indeed will be  to feed the additional  billions. 

No poverty and   Zero Hunger by 2030  are the top two priorities of  United Nations'  Sustainable Development  agenda initiated in 2015.   Recent  COVID-19  pandemic  has exposed the deep and wide flaws in the global food distribution system.  Approximately  2.37 billion people did not have access to adequate food in 2020. Geopolitical and socio-economic factors aggravated the situation. 

It is not that we don't produce enough.  According to  2020 Statistical Yearbook published by the  Food and Agricultural Organisation (FAO),  we produce 1.5 times more food than we require:  plentiful supplies  of sugar cane, corn and soybeans come from the Americas, rice, wheat and potatoes from Asia.  However  approximately one third of the food produced is annually wasted, for want of storage, transport, logistics and marketing facilities, inflicting  a whooping   $1 trillion loss per year to the global economy.  

If stringent steps are not taken,   millions will continue to  remain hungry forever.     The UN Food Systems Summit was held last  week  in New York.   With the  tagline of GoodFood4All, the summit's vision is  "a world where good food is affordable and accessible – where governments and businesses work together to provide it – and where farmers in every country grow food in a way that protects the planet." The basic question is not about optimum world population but  sustainable population that specific geographic regions can support. This calculation needs to done taking into consideration the natural resources and anthropogenic activities that lead to  irreversible drain on the ecosystem. For example it is estimated that human civilisation began with  a forest cover of roughly  60million square kilometres, which has shrunk to less than  40 million square kilometres as of now.  

We survived Malthusian Prophesies and Ehrlich's Apprehensions with advances in science and technology.   Will we be able to achieve  good food for 11 billion  in the same way?

 

Tailpiece

Soylent Green is a  bizarre 1973  Hollywood Movie  starring Charlton Heston.  Set in 2022, New York City is brimming with a population of 40 million.  The film  is a dystopian take on population explosion and acute scarcity of water, food  and shelter  leading to horrifying, macabre  consequences. 

REFERENCES:

1.Paul Ehrlich: Collapse of civilisation is near certainty within decades

2 The Population Bomb : Paul Ehrlich ,Macmillan (Revised 1971) ISBN:978-0345021397

3. Deforestation and world population sustainability: a quantitative analysis