Some men drink wine, and others water

 Some men drink wine..

“It cannot be said that we should think alike, when one drinks water and the other drinks wine.”

    True, and nicely put. Were we both in the same situation, and both reasoned correctly, it might be thought that we would both come to the same choice as to our drinking; and dressing, and and voting, etc.

     I hope I get some credit for this nice proof of the complexity of man’s mind, but I claim no originality; merely that I have brought it to your attention, from where it has been lurking these last 400 years. Or, indeed 2,400 years. 

     For Francis Bacon said it of himself, to underline the uniqueness of his thinking in his “Novum Organum”, and he (it seems [thank you Mr. Spedding]) was quoting Philocrates who said it of Demosthenes.

Aluminium Metabolism (1)

 Aluminium Metabolism (1): 

The bad news (B), and the good news (G) 

B1. Aluminium is toxic in milligram quantities.  Yet it is all around us by the ton. It is the most common element in the earth's crust, and 3rd most abundant element in our planet (after oxygen and silicon)[1]. (There seems to be no vital process for which it is essential. [2]) 

G1. However, its salts are amazingly insoluble [3]. The solubility product (KSP) (at 25º) of
AlPO4 ↔︎ Al3+ + PO43- is 9.8 x 10-21;
of Al(OH)3 ↔︎ Al3+ + 3OH- is 3 x 10-34. 

 Aluminium metal quickly forms a planar crystalline lattice with oxygen in the ratio 2Al:3O. This aluminium oxide has such stability that, in the form of corundum, it is used as an abrasive for cutting and polishing. With slight impurities (which add colour) it presents in 'nature' as sapphire, and ruby. 

B2. Nevertheless, dissolved aluminium is present in freshwater (in rivers, and lakes) at a concentration of  up to 400 parts per billion [4] (i.e. 14.8 µM), especially in acidic waters. In seawater the concentration is considerably less at between 0.013 and 5 ppb depending on the ocean. (Atlantic higher than Pacific.) Normal daily intake from water, food, dust, and topical antiperspirants, is estimated to be between 1 and 20 mg per day for an average human, but can be 1,000 mg/day for those taking Al-containing antacids. But a large part of that intake (e.g. 99%) is passed out in the faeces. A bit more is excreted in the urine (12-50 µg/day) setting a minimum estimate for the amount absorbed into blood. 

G2. However, it seems we can drink such water and live to a ripe old age, with signs of memory loss not normally showing till the age of 80 years or more, and sometimes not till 140 years. The 'average' human body-load is around 50 mg (30 - 200 mg). Daily intake is  from 1 - 20 mg/24 hours, say 10mg. Clearly we would fill up in 5 days were Al not excreted in faeces and urine. Of the daily intake of 10 mg, some 12  µg/day is excreted by the kidney [5,8], and essentially all the rest in faeces. Accumulation of Al is very slow,  e.g. "1 mg in 36 years," [5]. 

B3.  Unfortunately that is not true for everyone. Though the loss of Al via the kidney is tiny, it is also crucial. Patients with kidney failure are found to develop Dialysis Encephalopathy Syndrome (DES)[6] and Dialysis Osteomalacia (DOM)[7]. The former syndrome (DES) results from accumulation of aluminium in the brain, where it can bind to proteins and to nucleic acids (DNA and RNA), and can also raise the concentration of redox-active iron by displacement from iron-binding sites. The latter syndrome (DOM)  seems to be due to competition between Al3+ and Ca2+ at some stage in the bone-forming process. An aluminium serum level of even 6 µg/L is significantly linked to all-cause mortality within a year [11]. 

G3. Similar problems were observed with patients being fed 'parenterally', i.e. by intravenous infusion. However, once the importance of Al as a contaminant in the dialysis (or infusion) solution was realised, its concentration could be lowered (though that has proved extremely difficult), and the serum level monitored more closely.  Though we ingest c. 5 mg of Al per day, only c. 12 µg per day are absorbed into the blood. [5,8]

B4. Besides binding very tightly to organic and inorganic anions (hydroxide, silicate, phosphate, citrate, etc.), Al3+ binds very tightly to proteins and nucleic acids. Indeed,  Al3+ has been used for centuries in the tanning of leather, where it cross-links proteins, forming e.g. P1COO–Al3+ OH- Al3+ O-OCP2  bridges [5]. Naked DNA binds 1Al per 3 phosphorus atoms, but that rises to a 3:1 ratio with time, and to infinity if OH- is able to join in. Histones block 80% of the Al binding, but not all of it. Al-bridges may crosslink double-stranded DNA and prevent 'melting'.  [5]

Given the amount of DNA and protein in the human body, it is rather astonishing that we do not gradually fill up with bound aluminium. Indeed, we may [5].  Deposition in bone is probably irreversible, and average aluminium load in humans (30-50 mg) increases somewhat with age, though there is insignificant increase with age in the content of Al in brain [9]. Half of the body load is in bone, and a further 25% in the lungs [5] (perhaps as ingested dust). Average tissue loading on a dry wt. basis is 9 µg Al/gr dry wt. Kidney and spleen have raised levels of Al (up to 100 µg Al/gram dry wt.)   

Aluminium uptake from the gut can be increased 10-fold by the presence of citrate, presumably through the formation of electroneutral aluminium citrate [8]. Kidney excretion of Al may also be by the passive filtration of electroneutral aluminium citrate [10]. 

G4. The normal concentration of Al in the urine is 2–10 μg/L, but can be 10 times that in people exposed to aluminium. [10,8]  This suggests a process of passive filtration. But is there perhaps a mechanism for the active secretion of aluminium, via e.g. kidney and/or spleen?

REFERENCES

[1]  https://ehp.niehs.nih.gov/doi/10.1289/ehp.8665363

[2]  https://www.mdpi.com/2073-4395/12/4/888#, DOI: 10.3109/10408369709006422.

[3]  https://www.engineeringtoolbox.com/solubility-product-equilibrium-constant-ionic-solution-salt-Ksp-d_1952.html

[4]  https://www.lenntech.com/periodic/water/aluminium/aluminum-and-water.htm#ixzz7nTDMF4Kz

[5]  Ganrot, P.O. (1986) Metabolism and possible health effects of aluminum.https://ehp.niehs.nih.gov › abs › 10.1289 › ehp.8665363

[6]  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6550484/

[7]  https://pubmed.ncbi.nlm.nih.gov/6894520/

[8]  DeVoto & Yokel (1994) Environ Health Perspect. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1567445/

[9]  https://www.researchgate.net/publication/341242564_Aluminium_in_human_brain_tissue_from_donors_without_neurodegenerative_disease_A_comparison_with_Alzheimer%27s_disease_multiple_sclerosis_and_autism

[10]  R.A. Yokel, in Encyclopedia of Human Nutrition (Third Edition), (2013)

[11]  https://doi.org/10.1038/s41598-018-34799-5 

Nos adentramos en una Colonia Obrera

 Nos adentramos en la Colonia Obrera Cuauhtémoc

     Mi violín alemán barato (de Sandner) estaba mal configurado cuando lo compré hace 5 años en Veerkamp ("Palacio de la Musica", Ciudad de México); bueno, apenas configurado en absoluto. Las cuerdas, el puente, la cejilla estaban todos allí, pero no mostraban signos de haber sido trabajados para lograr la altura óptima de las cuerdas. Traté de profundizar los surcos del puente con un cuchillo de cocina dentado, pero el tono disminuía y tenía miedo de estropear la cubierta de las cuerdas. Decidí darme un capricho y gastar un poco de dinero en tenerlo "configurado correctamente".

     Google me encontró una lista de luthiers en México, con números de teléfono y páginas de Facebook. Elegí uno al azar, se llama Máximo Rodríguez Laudero, y me puse en contacto. Debía presentarme el miércoles a la 1 de la tarde en su nuevo atelier: Isabel la Católica 400, esquina con Delgado. Mi compañera me dijo que "no era una parte recomendable de la ciudad", y que el metro estaría abarrotado debido al cierre de la línea 12 descompuesta. Ella insistió en acompañarme –– en taxi.

     Llegamos al lugar con 3 - 4 minutos de adelanto. El taller de imprenta más cercano a la esquina nunca había oído hablar de un Máximo Rodríguez Laudero, ni de ningún luthier. Tampoco tenía conocimiento la imprenta de al lado. Yo tenía un número de teléfono pero, antes de que hubiéramos colgado, la puerta de la casa se abrió y un joven tímido apareció y nos condujo por un pasillo hasta una habitación al fondo. Esta contenía una mesita en la que yacía un violín desmontado y un pequeño armario de herramientas.  Máximo sólo había ocupado este taller durante dos días.

      Di mi diagnóstico. El aceptó. Regresaríamos en una hora y el trabajo costaría £20 (es decir, MX$500). Salimos a la calle, con una hora 'para matar'; caminamos, disfrutando del sol y la experiencia novedosa de este distrito explícitamente 'obrero'. El tráfico era modesto y no intrusivo. Pero dos ruidos distintos llamaron gradualmente nuestra atención.

     Resultó que básicamente todo la gente estaban escuchando el progreso del partido de fútbol en Qatar: México contra Arabia Saudita; en teléfonos móviles, en radios, en pantallas de televisión, en tiendas, en cabinas, en quioscos, en cafés, en imprentas, en papelerías. (México ganó 2:1 con gran alboroto de todos.)

     El otro ruido, desconocido, era el de las imprentas, porque estábamos en un área de la ciudad donde esencialmente todos los negocios se relacionaban con la impresión. Las tiendas eran papelerías, los puestos vendían camisetas estampadas y cintas estampadas, los quioscos vendían tazas impresas. Los trabajadores eran impresores, litógrafos, fotocopiadores, impresores de metal caliente, estampadores de láminas calientes, dibujantes. Vimos un anuncio de un taller: "Suajes y Suajados, urgentes". Mi compañera no tenía idea de qué habilidades estaban involucradas, y Google Translate fue de poca ayuda; algo relacionado con el estampado de cualquier material.

     Después de tres cuartos de hora, y un poco cansados, nos sentamos en un banco por unos minutos afuera de un taller en el que estaba operando una enorme prensa anticuada; un pesado volante girando, enormes mandíbulas apretando y soltando. Al lado, una maquina más moderna funcionaba con un ruido como una fotocopiadora gigante. Durante nuestra caminata debimos pasar frente a más de cien imprentas, tal vez doscientas.

     Y un fabricante de violines.