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Biomedical subjects

S Jain

Publications and source records attributed to S Jain.

At least 559 records · Page 31Linked to original sources
PubMed1990

Rat brain insulin degrading enzyme in insulin and thyroid hormones imbalances.

Rat brain insulin degrading enzyme activity and its relationship with insulin receptor were investigated in experimental hyperglycemia, hyperinsulinemia, hypothyroidism and hyperthyroidism. Insulin degrading enzyme activity was assessed in synaptosomes and high speed cytosol using [125I]insulin. Levels of insulin degrading enzyme were changed in high speed cytosol in insulin and thyroid hormone imbalances. These results suggest that insulin degrading enzyme in brain is predominantly active in cytosol and is subject to regulation by insulin and thyroid hormones. Probably it plays some role in long term effects of insulin in brain.

Animals↗
PubMed1990

Neonatal outcome following cesarean birth: a prospective study.

Neonatal morbidity and mortality in 573 singleton cesarean born infants was recorded. In 70% of women, it was a primary cesarean section. The neonatal mortality was 3.6% in babies born to primigravida mothers and 9.8% in infants of multigravida. Mortality in male and female infants was 5.73 and 9.65%, respectively. Preterm infants registered more than 7 times higher mortality than term infants. Birth weight below 2000 g and above 3500 g were associated with higher asphyxia rate and neonatal death. Neonatal morbidity frequently encountered was birth asphyxia (19.19%), septicemia (13.43%), jaundice (15.70%) and respiratory problems (23.0%).

Birth Weight↗
PubMed1990

Screening of Indian plants for biological activity: Part XIV.

Alcoholic extracts of 300 botanically identified plant materials from 275 plant species have been tested for various biological activities including chemotherapeutic and pharmacological screenings. Biological activities have been observed in 111 extracts. Follow-up studies have been carried out in some plants with confirmed activity. The active principles and results of these studies are reported.

Drug Evaluation, Preclinical↗
PubMed1990

Kala azar in an adult Libyan and review of visceral leishmaniasis in Libya.

Less than 30 confirmed cases of kala azar have been reported from Libya in this century. Many of the reported patients had stayed outside Libya and the majority were young children. After a span of fifty years we diagnosed an autochthonous case in an adult Libyan. The parasite was difficult to grow in N.N.N. culture media. During a small population survey in the area, no other case could be detected. Very little is known about the reservoir, vector, and sub-species of the parasite in Libya. The atypical symptoms, the rarity of cases detected and the difficulty of growing the parasite in vitro could be due to a different strain of the parasite causing visceral leishmaniasis in this area.

Adult↗
PubMed1989

Comparison of parenteral ciprofloxacin with clindamycin-gentamicin in the treatment of pelvic infection.

A prospective, randomized study of intravenous followed by oral ciprofloxacin compared with the combination of intravenous clindamycin and gentamicin was conducted in 122 women hospitalized with pelvic infections. Clinical diagnoses included endometritis (97 patients) and uncomplicated pelvic inflammatory disease (25 patients). Treatment successes for endometritis included 42 of 50 (84 percent) patients treated with ciprofloxacin compared with 35 of 47 (75 percent) treated with the clindamycin-gentamicin combination. Treatment successes for acute salpingitis included 10 of 10 (100 percent) treated with ciprofloxacin and 13 of 15 (87 percent) treated with clindamycin-gentamicin. Ciprofloxacin successfully eradicated Chlamydia trachomatis in 11 of 12 patients as did clindamycin-gentamicin in six of seven patients. In this study of pelvic infection, ciprofloxacin demonstrated efficacy comparable with the combination of clindamycin and gentamicin, and is effective against C. trachomatis.

Acute Disease↗
PubMed1989

Effect of crystal packing environment on conformation of the DNA duplex. Molecular structure of the A-DNA octamer d(G-T-G-T-A-C-A-C) in two crystal forms.

The structure of the octamer d(G-T-G-T-A-C-A-C) was determined in two different crystal forms, tetragonal P4(3)2(1)2 and hexagonal P6(1)22. Although in both forms the octamer adopts an A-DNA structure, there are significant conformational differences between them. In particular, the P-05' and the C5'-C4' bonds of the middle adenine (A5) residue exhibit a distorted trans-trans conformation in the tetragonal form, while they adopt the standard gauche-, gauche+ conformation in the hexagonal form. These differences can be correlated with certain features of the crystal packing interactions in the two forms. Furthermore, a comparison of the structures of various A-DNA octamers reveals that the A-form can be divided into two subclasses such that the hexagonal structures have helical and base pair parameters that fall closer to fiber A-DNA values, while in the tetragonal structures these parameters deviate more from fiber A-DNA. These results indicate that environment plays a major role in determining DNA conformation.

Base Composition↗
PubMed1989

Base only binding of spermine in the deep groove of the A-DNA octamer d(GTGTACAC).

The crystal structure of a complex of spermine with the DNA octamer d(GTGTACAC) has been determined at 2.0-A resolution. The alternating sequence adopts an A-DNA conformation with a novel purine-purine extra-Watson-Crick hydrogen bond involving the central guanine G3 (G11) and adenine A13 (A5) in the deep groove. The oligocation spermine binds in the floor of the deep groove by interacting with the bases and assumes an S-shape. Its dyad is coincident with that of the DNA, reminiscent of repressor binding to B-DNA. The terminal and central ammonium groups of the top half of spermine form hydrogen-bonding interactions to the 5'-bases, GTG, of one strand; then the spermine winds across the groove to interact with the corresponding set of bases on the other strand. The methylene groups of spermine form a hydrophobic cluster with the methyl groups of the thymines and the O6 atoms of the guanines of the TGT sequences on either side of the dyad. The observed mode of binding of spermine to A-DNA can serve as a model for deep groove binding in RNA and DNA-RNA hybrids that show a propensity also for the A-conformation. It will be of interest to see if base binding of spermine to DNA is involved in the regulation of gene expression, since spermine and other oligocations are ubiquitous in cells and their concentration is coupled to stages in cell cycle.

DNA↗
PubMed1989

Rat liver ATP-sulfurylase: purification, kinetic characterization, and interaction with arsenate, selenate, phosphate, and other inorganic oxyanions.

ATP-sulfurylase (ATP:sulfate adenylyltransferase; EC 2.7.7.4), the first enzyme of the two-step sulfate activation sequence, was purified extensively from rat liver cytosol. The enzyme has a native molecular mass of 122 +/- 12 kDa and appears to be composed of identical 62 +/- 6-kDa subunits. At 30 degrees C and pH 8.0 (50 mM Tris-Cl buffer containing 5 mM excess Mg2+), the best preparations have "forward reaction" specific activities of about 20 and 2 units X mg protein-1 with MoO4(2-) and SO4(2-), respectively. The reverse (ATP synthesis) specific activity is about the same as the forward molybdolysis activity. The kinetic constants under the above conditions are as follows: KmA = 0.21 mM, Kia = 0.87 mM, KmB = 0.18 mM, KmQ = 0.65 microM, Kiq = 0.11 microM, and KmP = 5.0 microM where A = MgATP, B = SO4(2-), Q = APS, and P = total PPi at 5 mM Mg2+. PPi is a mixed-type inhibitor with respect to MgATP and SO4(2-). SeO4(2-) is an alternative inorganic substrate with a Vmax about 20% that of SO4(2-). The product, APSe, is unstable. But in the presence of a sufficient excess of APS kinase, APSe is completely converted to PAPSe. The rate constant for nonenzymatic PAPSe hydrolysis was determined from measurements of the final steady-state reaction rate in the presence of limiting initial SeO4(2-) and a large excess of MgATP, ATP sulfurylase, APS kinase, and the other coupling enzymes and their cosubstrates. The results yielded a k of 2.4 +/- 0.5 X 10(-3) sec-1 (t1/2 ca. 5 min). Phosphate is an effective buffer for enzyme purification and storage but inhibits catalytic activity, particularly at low substrate concentrations. In the presence of buffer levels of Pi, the MgATP reciprocal plot of the SO4(2-)-dependent reaction is concave-up. Inorganic monovalent oxyanions are dead end inhibitors competitive with SO4(2-) and apparently uncompetitive with respect to MgATP. The relative potencies are in the order ClO3- greater than ClO4- greater than FSO3- greater than NO3-. Thiosulfate is also competitive with SO4(2-) but noncompetitive with respect to MgATP. Several divalent oxyanions (MoO4(2-), WO4(2-), CrO4(2-), and HAsO4(2-] promote the enzyme-catalyzed cleavage of MgATP to AMP and MgPPi. The ratio Vmaxf/KmA ranged from 0.7 to 200 for various reactive inorganic substrates. The cumulative results suggest the random binding of MgATP and the inorganic substrate but the ordered release of MgPPi before APS.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Phosphosulfate↗
PubMed1989

Electron spin resonance investigation of laser and heated metal-tip-induced free radical formation in various tissues.

The short-lived free radical formation accompanying laser irradiation and laser-heated metal tip contact was examined using electron spin resonance (ESR) spin-trap methodology. Various tissues (canine myocardium, human aorta, liver, and spleen) were irradiated by argon-ion (continuous wave [CW] and pulse) and YAG (CW) lasers employing both naked fiber and a laser-heated metal tip. All showed the formation of primarily carbon-centered, not oxygenated, free radicals, together with some minor unidentified species. This implies that the backbones of amino acids, lipids, or other biological building blocks are cleaved during the irradiation or thermal treatment. Different tissues produce similar radicals but with different amounts when irradiated by argon-ion, YAG, and laser-heated metal tip sources. The amount of the free radicals formed depends on the laser power (within 5-15 W). Compared to the naked fiber, the laser-heated metal tip shows the generation of at least twice the amount of free radicals. The possible relationship of the free radical formation to tissue injury is briefly discussed.

Animals↗
PubMed1989

Desmoplastic malignant melanoma and its variants. A study of 45 cases.

Forty-five tumors exhibiting the histological features of desmoplastic malignant melanoma or its variant, neurotropic melanoma, were found among approximately 4,500 soft-tissue tumors referred in consultation from Australia and New Zealand. All patients were Caucasians. Tumors fell into three groups: (a) desmoplastic melanoma with an atypical intra-epidermal melanocytic component (classical desmoplastic melanoma) (12 cases); (b) desmoplastic melanoma without an atypical intra-epidermal melanocytic component (de novo desmoplastic melanoma) (21 cases); (c) predominantly nerve-centered superficial malignant tumors with or without an atypical intra-epidermal melanocytic component (12 cases). Three of the nerve-centered tumors were associated with pigmentary abnormalities in the overlying skin. The patients' ages ranged from 42 to 91 years, with a peak in the seventh decade; 31 patients were male and 14 were female. Lesions were located in the head and neck (35 cases), shoulder and arm (four), back and chest (three), abdomen (one), thigh (one), and leg (one). Three tumors arose in irradiated areas, and one occurred on the face of a radiotherapist. Melanin was found in only four tumors, but the S-100 protein stain was positive in 19 tumors and negative in three. Follow-up details of 42 patients were available. In follow-up times from 4 months to 15 years (mean, 4.6 years), 15 patients (36%) had died of the disease or were terminally ill; 24 (57%) were alive with no apparent residual tumor; and three (7%) had died of other causes. Twenty-three patients (55%) developed one or more local recurrences; 17 (40%) developed distant spread, including extension into the cranial cavity along nerves; and 14 (33%) had both local recurrence and distal spread. Nine (82%) of 11 patients with nerve-centered tumors died or were terminally ill. The usual treatment was surgical. Most uncontrolled recurrences were resistant to chemotherapy and radiotherapy; however, two patients responded well, one to chemotherapy and one to radiotherapy. Our observation support Reed and Leonard's metaplastic explanation for the varied differentiation seen in desmoplastic melanomas.

Adult↗
PubMed1989

Lymphocyte proliferative responses to human immunodeficiency virus antigens in vitro.

All HIV seronegative (HIV Ab-) and most HIV seropositive (HIV Ab+) individuals' lymphocytes failed to proliferate in primary cultures in response to purified HIV or to recombinant envelope and core antigens of HIV, even in the presence of recombinant interleukin 2 (rIL-2). Most HIV Ab- and HIV Ab+ individuals' lymphocytes, however, could proliferate or be induced by rIL-2 to proliferate in response to lysates of Escherichia coli or Saccharomyces cerevisiae. These findings indicate selective defects in lymphocyte proliferative responses to HIV antigens before the development of AIDS in which lymphocytes are unable to proliferate in response to any antigens. These defects in cell-mediated immune responses to HIV antigens are likely to play an important role in the pathobiology of HIV infections. Although intact HIV or glycosylated gp120 envelope protein of HIV are involved in these defects, a non-glycosylated recombinant form of the HIV gp120 envelope (ENV2-3) and p25 core proteins did not inhibit antigen- or mitogen-driven lymphocyte proliferation.

AIDS-Related Complex↗