Natural radioactivity of Indian building materials and by-products

Conventional building materials and by-products from coal power plants which are being used or have the potential for use in buildings in India were analysed for natural radioactivity due to the presence of 226Ra, 232Th and 40K using gamma-ray spectroscopy. The materials examined in this work showed the radioactivity levels below the limit estimated from radium equivalent activity the criterion formula for gamma-activity suggested for acceptable radiation doses attributable to building materials in OECD countries.

High prevalence of sexually transmitted and blood-borne infections amongst the inmates of a district jail in Northern India

Two hundred and forty male and 9 female jail inmates confined for various crimes in a district jail near Delhi were screened for sexually transmitted and blood-borne diseases including HIV, syphilis and hepatitis B and C viral infections, skin diseases etc. The inmates were aged 15-50 years with a mean of 24.8+/-0.11. Their alleged criminal background, period of stay in the jail, drug addiction, education, birth place, marital status, sexual activity, and clinical complaints were recorded by an anonymous questionnaire. Serum samples were tested for antibodies against HIV (1+2), hepatitis C (HCV), Treponema pallidum and for hepatitis B surface antigen (HBsAg). Sputum examination was done for acid-fast bacilli. Out of the 240 men, 115 were married and 125 unmarried. One hundred and eighty-four (76.6%) men gave history of penetrative sex. Of the 184, 53 (28.8%) were homosexuals or bisexuals and 131 (71.2%) had sex with women only. Sixty of the 131 (45.8%) were faithful to their partners while 124 gave a history of having multiple sexual partners and 100 of them (80.6%) had unprotected sex. Eighty-three of these 100 also had had sex with commercial sex workers (CSWs). One hundred and twenty-six were addicted for alcohol, 44 for smack/charas and 8 had a history of intravenous drug abuse. One hundred and seventy-four were not aware of AIDS. On examination 28 of the 240 (11.6%) had active hepatitis with or without a history of jaundice in the last 2 years, 25 (10.4%) active pulmonary tuberculosis (TB) and 11 (4.6%) had syphilitic ulcers on the penis. Four-fifths of the teenagers confined to a particular barrack had moderate to severe scabies. Three males (1.3%) were found to be Western blot confirmed HIV-1 positive while 28 (11.1%) men and 2 (22.2%) women were positive for HBsAg. Twelve (5.0%) men but no women, were found to be positive for anti-HCV antibodies. Out of the 3 HIV-positive persons, one was an intravenous drug user (IVDU), second was a drug addict and frequent CSW visitor while the third was a homosexual. This pilot study gives an indication that sexually transmitted and blood-borne infections are highly prevalent in jail premises and pose a threat of rapid spread of these infections through IVDU and homosexuality.

A proposal for nomenclature of aldehyde dehydrogenases in Saccharomyces cerevisiae and characterization of the stress-inducible ALD2 and ALD3 genes

The complete sequencing of the genome of Saccharomyces cerevisiae indicated that this organism contains five genes encoding aldehyde dehydrogenases. YOR374w and YER073w correspond to the mitochondrial isoforms and we propose as gene names ALD4 and ALD5, respectively. YPL061w has been described as the cytoplasmic constitutive isoform and named ALD6. We characterize here the tandem-repeated ORFs YMR170c and YMR169c as the cytoplasmic stress-inducible isoforms, with gene names ALD2 and ALD3, respectively. The expression of ALD2 and ALD3 is dependent on the general-stress transcription factors Msn2,4 but independent of the HOG MAP kinase pathway. ALD3 is induced by a variety of stresses, including osmotic shock, heat shock, glucose exhaustion, oxidative stress and drugs. ALD2 is only induced by osmotic stress and glucose exhaustion. A double null mutant, ald2 ald3, exhibited unchanged sensitivity to any of the above stresses. The only phenotype detected in this mutant was a reduced growth rate in ethanol medium as compared to the wild type.

Purification and characterization of a major zinc binding protein from renal brush border membrane of rat

In spite of the fact that zinc is an essential trace element, mechanisms that contribute to zinc homeostasis in mammals are poorly understood. An attempt has been made to identify and purify zinc binding components from renal brush border membrane (BBM), which could be involved in the binding of zinc and the subsequent translocation across the BBM. A 40 kDa major zinc binding protein has been identified and purified from renal BBM, which showed a dissociation constant (Kd) of 211 microM and maximal binding (Bmax) of 207 nmol/mg protein. 8 g zinc atoms could interact with 1 mol of protein. Specificity of the protein for zinc was checked by metal displacement and UV-absorption assay. It was found that only Cd2+ could displace the zinc bound to the protein. Other metals tested (Cu2+, Mg2+, Ca2+) did not show any interaction with the protein. These data indicated that purified protein is highly specific and has a high affinity for zinc. The carbohydrate content was found to be 7.85 mg% in the purified protein. Immunofluorescence localization of this protein in kidney sections revealed that this major zinc binding protein is exclusively localized in the proximal convoluted tubules. These results suggested that the 40 kDa major zinc binding transmembrane glycoprotein is highly specific for zinc and has a high affinity for zinc.

Efficacy of curcumin in the management of chronic anterior uveitis

Curcumin, obtained from rhizomes of Curcuma longa, was administered orally to patients suffering from chronic anterior uveitis (CAU) at a dose of 375 mg three times a day for 12 weeks. Of 53 patients enrolled, 32 completed the 12-week study. They were divided into two groups: one group of 18 patients received curcumin alone, whereas the other group of 14 patients, who had a strong PPD reaction, in addition received antitubercular treatment. The patients in both the groups started improving after 2 weeks of treatment. All the patients who received curcumin alone improved, whereas the group receiving antitubercular therapy along with curcumin had a response rate of 86%. Follow up of all the patients for the next 3 years indicated a recurrence rate of 55% in the first group and of 36% in the second group. Four of 18 (22%) patients in the first group and 3 of 14 patients (21%) in the second group lost their vision in the follow up period due to various complications in the eyes, e.g. vitritis, macular oedema, central venous block, cataract formation, glaucomatous optic nerve damage etc. None of the patients reported any side effect of the drug. The efficacy of curcumin and recurrences following treatment are comparable to corticosteroid therapy which is presently the only available standard treatment for this disease. The lack of side effects with curcumin is its greatest advantage compared with corticosteroids. A double blind multi-centric clinical trial with this drug in CAU is highly desirable to further validate the results of the present study.

Role of DNA polymerase beta in the excision step of long patch mammalian base excision repair

The two base excision repair (BER) subpathways in mammalian cells are characterized by the number of nucleotides synthesized into the excision patch. They are the "single-nucleotide" BER pathway and the "long patch" (several nucleotides incorporated) BER pathway. Both of these subpathways involve excision of a damaged base and/or nearby nucleotides and DNA synthesis to fill the excision gap. Whereas DNA polymerase beta (pol beta) is known to participate in the single-nucleotide BER pathway, the identity of polymerases involved in long patch BER has remained unclear. By analyzing products of long patch excision generated during BER of a uracil-containing DNA substrate in mammalian cell extracts we find that long patch excision depends on pol beta. We show that the excision of the characteristic 5'-deoxyribose phosphate containing oligonucleotide (dRP-oligo) is deficient in extracts from pol beta null cells and is rescued by addition of purified pol beta. Also, pol beta-neutralizing antibody inhibits release of the dRP-oligo in wild-type cell extracts, and the addition of pol beta after inhibition with antibody completely restores the excision reaction. The results indicate that pol beta plays an essential role in long patch BER by conducting strand displacement synthesis and controlling the size of the excised flap.

Membrane fluidity affects functions of Cdr1p, a multidrug ABC transporter of Candida albicans

Earlier, we have shown that the overexpression of an ABC transporter, CDR1, is involved in the emergence of multidrug resistance in Candida albicans. In this study, we checked its function in vivo by expressing it in different isogenic Saccharomyces cerevisiae erg mutants, which accumulated various intermediates of the ergosterol biosynthesis and thus altered the membrane fluidity. Functions like the accumulation of rhodamine 123, beta-estradiol, fluconazole and floppase activity associated with Cdr1p were measured to ascertain their responses to an altered membrane phase. The floppase activity appeared to be favoured by an enhanced membrane fluidity, while the effluxing of substrates and Cdr1p's ability to confer multidrug resistance were significantly reduced. We demonstrate that only some of the functions of Cdr1p were affected by an altered lipid environment.

Thyroid hormones modulate zinc transport activity of rat intestinal and renal brush-border membrane

Thyroid hormone status influences the Zn2+ and metallothionein levels in intestine, liver, and kidney. To evaluate the impact of thyroid hormones on Zn2+ metabolism, Zn2+ uptake studies were carried out in intestinal and renal brush-border membrane vesicles (BBMV). Steady-state Zn2+ transport in intestinal and renal cortical BBMV was increased in hyperthyroid (Hyper-T) rats and decreased in the hypothyroid (Hypo-T) rats relative to euthyroid (Eu-T) rats. In both the intestinal and renal BBMV, Hyper-T rats showed a significant increase in maximal velocity compared with Eu-T and Hypo-T rats. Apparent Michaelis constant was unaltered in intestinal and renal BBMV prepared from the three groups. Fluorescence anisotropy of diphenyl hexatriene was decreased significantly in intestinal and renal brush-border membrane (BBM) isolated from Hyper-T rats compared with Hypo-T and Eu-T rats. A significant reduction in the microviscosity and transition temperature for Zn2+ uptake in intestinal and renal BBM from Hyper-T rats is in accordance with the increased fluidity of these BBMs. These findings suggest that the increased rate of Zn2+ transport in response to thyroid hormone status could be associated with either an increase in the number of Zn2+ transporters or an increase in the active transporters due to alteration in the membrane fluidity. Thus the thyroid hormone-mediated change in membrane fluidity might play an important role in modulating Zn2+ transport activity of intestinal and renal BBM.

Evaluation of antiallergic activity (type I hypersensitivity) of Inula racemosa in rats

Alcoholic extract of root of Inula racemosa, was studied for its antiallergic effect in experimental models of type I hypersensitivity, viz. egg albumin induced passive cutaneous anaphylaxis (PCA) and mast cell degranulation in albino rats. The alcoholic extract was prepared by the process of continuous heat extraction. LD50 of this extract was found to be 2100 +/- 60 mg/kg, i.p. Assessment of protection against egg albumin induced passive cutaneous anaphylaxix by different doses of Inula racemosa was done by giving drug intraperitoneally or orally for seven days or once only. Mast cell degranulation studies were done by using compound 48/80 as degranulation agent with same dosage schedule. Inula racemosa (i.p. as well as p.o.) showed significant protection against egg albumin induced PCA. Protection against compound 48/80 induced mast cell degranulation by alcoholic extract of Inula racemosa (single dose) was similar to that of disodium cromoglycate. The seven days drug treatment schedule showed greater protection than disodium cromoglycate intraperitoneally. The results suggest that Inula racemosa possesses potent antiallergic properties in rats.

Study of 222Rn concentrations in some dwellings of Rajasthan

Total potential alpha energy concentrations due to radon progeny were measured in 143 dwellings of Udaipur, Bikaner, and Banswara towns of Rajasthan province of India with LR-115 type II detectors. The geometric mean values of total potential alpha energy concentrations in these three towns were found to be 1.9 x 10(-7) J m(-3), 1.2 x 10(-7) J m(-3) and 1.7 x 10(-7) J m(-3) with a geometric standard deviation of 2.2, 2.2, and 2.5, respectively. The estimated lifetime risk of lung cancer due to indoor radon exposure for a total population of study area was estimated to be 6.7 x 10(-3) or 0.67%. The mean relative loss of life expectancies were 0.20%, 0.12%, and 0.18%, respectively.

Asymmetric distribution of phosphatidylethanolamine in C. albicans: possible mediation by CDR1, a multidrug transporter belonging to ATP binding cassette (ABC) superfamily

By using two molecular probes, we demonstrate that only 4% of total phosphatidylethanolamine (PtdEtn) in the plasma membrane (PM) of a human pathogenic yeast, Candida albicans, is present in its external half. Evidence is presented to show that the availability of PtdEtn could be related to the expression of a multidrug transporter CDR1 of C. albicans, and the process is energy-dependent. A homozygous CDR1 disruptant strain of C. albicans shows almost 23% reduction in the external labelling of PtdEtn. This report shows that, similar to human MDRs, yeast multidrug transporter could also be involved in aminophospholipid translocation.

Effect of growth hormone therapy in burn patients on conservative treatment

Evaluation of growth hormone therapy in burns is limited and none is reported from developing countries where burns still carry high mortality. We analysed serial observations on the clinical and biochemical profiles in 13 patients with second and third degree burns who received recombinant human growth hormone (rhGH) (0.5 IU/kg body wt) for 2 weeks in addition to standard conservative treatment and in 9 patients who were managed with standard conservative treatment only. The two groups of patients had burns, comparable in extent and severity. Additional rhGH treatment resulted in improved wound healing (p < 0.001), delayed separation of eschars (p < 0.01), increase in haemoglobin (p < 0.05), serum albumin (p < 0.01), calcium (p < 0.05), phosphorus (p < 0.001), glomerular filtration rate (p < 0.05) and 7 fold elevation in IGF-1. Also, a reduction in weight loss (p < 0.01), nitrogen production rate (p < 0.05), catabolic index (p < 0.01), duration of sepsis (p < 0.01) and hospital stay by 40% (p < 0.01) was noted with rhGH therapy. Transient hypercalcemia (3 patients), albuminuria (2 patients) and elevated blood glucose (one patient) were noted in the rhGH treated group not necessitating any specific therapy. Mortality in rhGH treatment group was 8.3% compared to 44.5% in the "no rhGH" treatment group. These observations suggest significant benefits of short term rhGH treatment in burn patients on conservative management.

Vertical-scanning mutagenesis of a critical tryptophan in the minor groove binding track of HIV-1 reverse transcriptase. Molecular nature of polymerase-nucleic acid interactions

While sequence-specific DNA-binding proteins interact predominantly in the DNA major groove, DNA polymerases bind DNA through interactions in the minor groove that are sequence nonspecific. Through functional analyses of alanine-substituted mutant enzymes that were guided by molecular dynamics modeling of the human immunodeficiency virus type 1-reverse transcriptase and DNA complex, we previously identified a structural element in reverse transcriptase, the minor groove binding track (MGBT). The MGBT is comprised of five residues (Ile94, Gln258, Gly262, Trp266, and Gln269) which interact 2-6 base pairs upstream from the polymerase active site in the DNA minor groove and are important in DNA binding, processivity, and frameshift fidelity. These residues do not contribute equally; functional analysis of alanine mutants suggests that Trp266 contributes the most to binding. To define the molecular interactions between Trp266 and the DNA minor groove, we have analyzed the properties of eight mutants, each with an alternate side chain at this position. A refined molecular dynamics model was used to calculate relative binding free energies based on apolar surface area buried upon complex formation. In general, there was a strong correlation between the relative calculated binding free energies for the alternate residue 266 side chains and the magnitude of the change in the properties which reflect template-primer interactions (template-primer dissociation rate constant, Ki,AZTTP, processivity, and frameshift fidelity). This correlation suggests that hydrophobic interactions make a major contribution to the stability of the polymerase-DNA complex. Additionally, tyrosine and arginine substitutions resulted in mutant enzymes with DNA binding properties better than predicted by buried surface area alone, suggesting that hydrogen bonding could also play a role in DNA binding at this position.

A critical evaluation of copper metabolism in Indian Wilson's disease children with special reference to their phenotypes and relatives

Wilson's disease is an autosomal recessive disorder of copper accumulation in various organs, with most common clinical manifestations such as hepatic, neurological, and renal dysfunctions. Serum copper and ceruloplasmin in Wilson's disease were significantly lower as compared to normals, controls, and relatives of Wilson's disease patients, whereas marked hypercupriuria (145+/-7 microg/24 h) was observed in Wilson's children only. A good correlation (r=0.92) was found between non-ceruloplasmin-bound copper and 24-h urinary copper excretion in Wilson's disease patients. Further, copper studies among the different phenotypes of Wilson's disease revealed substantially low serum ceruloplasmin and a marked hypercupriuria in Wilson's disease children associated with renal tubular acidosis as compared to the patients with either hepatological or neurological manifestations. Serum ceruloplasmin levels in 14 patients of Wilson's disease were between 14 and 20 mg/dL. These patients of Wilson's disease were confirmed by measuring liver biopsy copper, which was about nine times higher than normal hepatic copper content. During the family screening by copper studies, four asymptomatic siblings were diagnosed for Wilson's disease. These subjects were then started on D-penicillamine therapy because presymptomatic treatment prevents progression of the disease complications.

Identification of a novel copper-binding protein from the liver of Indian childhood cirrhosis: purification and physicochemical characterization [corrected]

A novel copper-binding protein was identified in the liver supernatant (100,000 x g) of Indian childhood cirrhosis (ICC), purified to apparent homogeneity and characterized [corrected]. Purified major copper-binding protein (MCuBP) is solely responsible for binding about 35% of the total supernatant copper. Elution profile of ICC liver supernatant on Sephadex G-75 column chromatography showed three peaks. About 60% of the total supernatant copper was resolved in peak II, whereas zinc content was insignificant in this peak. But peak II was almost missing in a gel elution profile of control liver supernatant. The control group included cases of various liver diseases viz. neonatal hepatitis, septicemia, and mixed nodular cirrhosis. Copper-binding proteins of peak II further purified on ion-exchange chromatography and elution profile showed that peak II was a MCuBP with high copper-binding capacity (10 g atoms/mol of native protein). SDS-PAGE of this protein also revealed the existence of a single band with molecular mass of about 50 kD. UV spectra of MCuBP showed the maximal absorbance at 254 nm. Unlike the classical metallothionein, the amino acid composition of MCuBP revealed the presence of aromatic amino acids and higher content of glutamic acid and aspartic acid followed by glycine and serine. The ratio (0.3) of basic amino acids to acidic amino acids strongly indicates that it is an acidic protein. The cysteine content in this protein was insignificant, which further corroborates the possibility that the acidic amino acids might be prominent candidates for binding copper. Thus, the 50-kD MCuBP apparently makes a major contribution to the total copper-binding activity in ICC liver cytosol and may play a significant role in hepatic intracellular copper accumulation.

Identification of 5'-deoxyribose phosphate lyase activity in human DNA polymerase gamma and its role in mitochondrial base excision repair in vitro

Mitochondria have been proposed to possess base excision repair processes to correct oxidative damage to the mitochondrial genome. As the only DNA polymerase (pol) present in mitochondria, pol gamma is necessarily implicated in such processes. Therefore, we tested the ability of the catalytic subunit of human pol gamma to participate in uracil-provoked base excision repair reconstituted in vitro with purified components. Subsequent to actions of uracil-DNA glycosylase and apurinic/apyrimidinic endonuclease, human pol gamma was able to fill a single nucleotide gap in the presence of a 5' terminal deoxyribose phosphate (dRP) flap. We report here that the catalytic subunit of human pol gamma catalyzes release of the dRP residue from incised apurinic/apyrimidinic sites to produce a substrate for DNA ligase. The heat sensitivity of this activity suggests the dRP lyase function requires a three-dimensional protein structure. The dRP lyase activity does not require divalent metal ions, and the ability to trap covalent enzyme-DNA complexes with NaBH4 strongly implicates a Schiff base intermediate in a beta-elimination reaction mechanism.

Identification of polymorphic mutant alleles of CaMDR1, a major facilitator of Candida albicans which confers multidrug resistance, and its in vitro transcriptional activation

CaMDR1 (Candida albicans Multi Drug Resistance) encodes a major facilitator whose expression in Saccharomyces cerevisiae confers resistance to several unrelated drugs. We describe here the identification and molecular characterization of seven mutant alleles of CaMDR1 (CaMDR1-1 to 1-7). The complete sequencing of CaMDR1 alleles revealed several in-frame point mutations leading to a change in amino-acid residues where insertion/replacement of an aspartate residue in a serine-asparagine-aspartate-rich domain was most noteworthy. Interestingly, these alleles showed a distinct drug resistance profile. The expression of CaMDR1, or of its alleles, in C. albicans cells was enhanced by benomyl, methotrexate and several other unrelated drugs, and was more pronounced in at least one of the azole-resistant clinical isolates.

Plasma zinc status in Indian childhood tuberculosis: impact of antituberculosis therapy

SETTING

Department of Paediatrics and Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, India.

OBJECTIVE

To assess the plasma zinc status in children with tuberculosis and to correlate it with nutritional status, activity and severity of disease in relation to antituberculosis therapy.

DESIGN

The plasma zinc status of 50 children with different forms of tuberculosis was compared with 10 healthy and 10 malnourished children without tuberculosis at 0, 1, 2, 3 and 6 months of antituberculosis therapy.

RESULT

The mean plasma zinc concentration in children with pulmonary tuberculosis (n = 20) was 68.65+/-2.50 microg/dl, central nervous system (CNS) tuberculosis (n = 10) was 64.20+/-3.82 microg/dl, tuberculous lymphadenitis (n = 10) was 63.2+/-3.77 microg/dl and disseminated tuberculosis (n = 10) was 59.0+/-2.75 microg/dl at 0 months. The mean plasma zinc level of healthy children was 129.10+/-3.01 microg/dl and in malnourished non-tuberculous children it was 108.40+/-3.16 microg/dl. Thus children with tuberculosis had significantly lower plasma zinc level than those without tuberculosis, irrespective of their nutritional status (P < 0.001). There was a significant rise in zinc level at the end of 6 months of antituberculosis therapy (P < 0.001).

CONCLUSION

Plasma zinc status may prove to be a good objective marker for monitoring the severity of the disease and the response to therapy.

Mammalian abasic site base excision repair. Identification of the reaction sequence and rate-determining steps

Base excision repair (BER) is one of the cellular defense mechanisms repairing damage to nucleoside 5'-monophosphate residues in genomic DNA. This repair pathway is initiated by spontaneous or enzymatic N-glycosidic bond cleavage creating an abasic or apurinic-apyrimidinic (AP) site in double-stranded DNA. Class II AP endonuclease, deoxyribonucleotide phosphate (dRP) lyase, DNA synthesis, and DNA ligase activities complete repair of the AP site. In mammalian cell nuclear extract, BER can be mediated by a macromolecular complex containing DNA polymerase beta (beta-pol) and DNA ligase I. These two enzymes are capable of contributing the latter three of the four BER enzymatic activities. In the present study, we found that AP site BER can be reconstituted in vitro using the following purified human proteins: AP endonuclease, beta-pol, and DNA ligase I. Examination of the individual enzymatic steps in BER allowed us to identify an ordered reaction pathway: subsequent to 5' "nicking" of the AP site-containing DNA strand by AP endonuclease, beta-pol performs DNA synthesis prior to removal of the 5'-dRP moiety in the gap. Removal of the dRP flap is strictly required for DNA ligase I to seal the resulting nick. Additionally, the catalytic rate of the reconstituted BER system and the individual enzymatic activities was measured. The reconstituted BER system performs repair of AP site DNA at a rate that is slower than the respective rates of AP endonuclease, DNA synthesis, and ligation, suggesting that these steps are not rate-determining in the overall reconstituted BER system. Instead, the rate-limiting step in the reconstituted system was found to be removal of dRP (i.e. dRP lyase), catalyzed by the amino-terminal domain of beta-pol. This work is the first to measure the rate of BER in an in vitro reaction. The potential significance of the dRP-containing intermediate in the regulation of BER is discussed.

Thermodynamics of human DNA ligase I trimerization and association with DNA polymerase beta

The interaction between human DNA polymerase beta (pol beta) and DNA ligase I, which appear to be responsible for the gap filling and nick ligation steps in short patch or simple base excision repair, has been examined by affinity chromatography and analytical ultracentrifugation. Domain mapping studies revealed that complex formation is mediated through the non-catalytic N-terminal domain of DNA ligase I and the N-terminal 8-kDa domain of pol beta that interacts with the DNA template and excises 5'-deoxyribose phosphate residue. Intact pol beta, a 39-kDa bi-domain enzyme, undergoes indefinite self-association, forming oligomers of many sizes. The binding sites for self-association reside within the C-terminal 31-kDa domain. DNA ligase I undergoes self-association to form a homotrimer. At temperatures over 18 degreesC, three pol beta monomers attached to the DNA ligase I trimer, forming a stable heterohexamer. In contrast, at lower temperatures (<18 degreesC), pol beta and DNA ligase I formed a stable 1:1 binary complex only. In agreement with the domain mapping studies, the 8-kDa domain of pol beta interacted with DNA ligase I, forming a stable 3:3 complex with DNA ligase I at all temperatures, whereas the 31-kDa domain of pol beta did not. Our results indicate that the association between pol beta and DNA ligase I involves both electrostatic binding and an entropy-driven process. Electrostatic binding dominates the interaction mediated by the 8-kDa domain of pol beta, whereas the entropy-driven aspect of interprotein binding appears to be contributed by the 31-kDa domain.

Pituitary-gonadal hormones during prolonged residency in Antarctica

Plasma luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin (PRL) and testosterone levels were measured in nine eugonadal men in New Delhi and during the 1st week of different months of their stay at Dakshin Gangotri in Antarctica. During their 12-month stay in Antarctica, they were exposed to a severely cold climate, long polar nights and polar days, high wind velocity, increased amounts of solar and ultraviolet radiation and geomagnetism, as well as physical and social isolation. Plasma testosterone tended to increase in March, but a significant increase (P < 0.05) was not seen until April. The mean testosterone levels in May, June, September and November were also significantly higher than the March or New Delhi values. The absolute values of LH, FSH and PRL did not show any month-to-month changes in Antarctica. However, when the hormone levels were expressed as a percentage of the individual annual Antarctic mean, significant differences as a percentage of the individual annual Antarctic mean, significant differences were observed. The testosterone peak in April, May and June was associated with an increase in LH. The nadirs of testosterone, LH, FSH and PRL were seen in either July or August. FSH showed the highest values in March, whereas the highest PRL values were seen in November. These observations suggest the presence of circannual variations in gonadotropin, PRL and LH in Antarctica which are independent of polar days and polar nights. It appears that factors other than the duration of daylight might be involved in regulating these changes. The significance of maintenance of testosterone levels in the supra-physiological range in Antarctica remains unknown but may be important in acclimatization/habituation to the extreme polar cold by increasing basal metabolic rate, protein synthesis and erythropoiesis.