Biomedical subjects
Publications and source records attributed to S T Ali.
Three compounds, pubadysone [11 alpha-hydroxy-18,20-oxido-3-oxo-pregna-1,4,17(20)-triene] (1), puboestrene [3-acetoxy-17-oxo-1,3,5(10)-estratriene] (2) and pubamide [3,18-dioxo-11 alpha-hydroxycona-1,4-diene] (3), have been isolated from the bark of Holarrhena pubescens. Their structures have been established through spectroscopic studies.
Following a general procedure developed previously [Ann. Henri Poincaré 1, 685 (2000)], here we construct Wigner functions on a phase space related to the similitude group in two dimensions. Since the group space in this case is topologically homeomorphic to the phase space in question, the Wigner functions so constructed may also be considered as being functions on the group space itself. Previously the similitude group was used to construct wavelets for two-dimensional image analysis; we discuss here the connection between the wavelet transform and the Wigner function.
An in vitro normal human epidermal keratinocytes (NHEK) model was used to study and to characterize the protease stimulated by the mustards 2-chloroethyl ethyl sulphide (CEES), 2-chloro-N-(2-chloroethyl)-N-methylethanamine hydrochloride (nitrogen mustard, HN2), and Bis-2-chloroethyl sulfide (sulfur mustard, HD). The results obtained by using a chromozym (TRY) peptide substrate protease assay showed the optimum mustard concentration and time for protease stimulation to be about 200 microM CEES, 100 microM HN2 or HD, and 16 hours. The mustard-stimulated protease was membrane-bound, and was inhibited by adding a Ca2+ chelator EGTA (2 mM), BAPTA AM (50 microM) or a serine protease inhibitor diisopropyl fluoro-phosphate DFP (1 mM), or a protein synthesis inhibitor cycloheximide (10 microM) in the extracellular medium. These results suggest that one of the mechanisms of mustard toxicity is via the stimulation of a trypsin/chymotrypsin like serine protease, which is dependent on Ca2+ and new protein synthesis. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed a mustard-stimulated approximately equal to 70-80 KDa protein band that was associated with protease activity which was inhibitable by EGTA, BAPTA, DFP or cycloheximide. This mustard-stimulated protein (protease) may serve as a diagnostic tool for mustard exposure as well as an assay for screening prospective antivesicant protease inhibitor drugs.
Chemical cross-linking was used to study the interactions of the anti-cell-death protein Bcl2 with other proteins in the outer mitochondrial membrane. Cross-linking of mitochondrial surface proteins produced a large Bcl2-containing complex (>200 kDa), and a Bcl2-derived peptide was shown to cross-link specifically with a mitochondrial protein identified by immunoblotting as Raf-1 kinase.
The value of bulbocavernosus reflex latency verses nerve conduction velocity of the dorsal nerve of penis and penile brachial index was evaluated in 50 impotent individuals infected with the human immunodeficiency virus, type 1 (both symptomatic and asymptomatic) and in 50 aged matched HIV-1 sero-negative impotent men serving as controls. All the subjects were neurologically asymptomatic and non demented. Both HIV-1 infected asymptomatic and symptomatic impotent patients exhibited a significant decrease (P < 0.0005) in the nerve conduction velocity of the dorsal nerve of penis as well as penile branchial index from the controls of the same age group. The latency of bulbocavernosus showed no significant difference between the groups and was within the normal limits. A non-significant association in the study parameters between HIV-1 infected asymptomatic and AIDS positive impotent men was also observed. These findings suggest that impotence and altered erectile electrodiagnostic responses are likely to be associated with an increased frequency to neuropathy in these patients irrespective of their disease state.
The structure of a lipoyl domain from the pyruvate dehydrogenase multienzyme complex of Escherichia coli has been determined by means of nuclear magnetic resonance spectroscopy. A total of 549 nuclear Overhauser effect distance restraints, 52 phi torsion angle restraints and 16 slowly exchanging amide protons were employed as input for the structure calculations. These were performed using a combined distance geometry-simulated annealing strategy. The domain is a hybrid between the N and C-terminal halves of the first and third lipoyl domains, respectively, of the dihydrolipoyl acetyltransferase component of the E. coli multienzyme complex, representing residues 1 to 33 and 238 to 289 (wild-type numbering). The lipoyl-lysine residue was also replaced by glutamine. Nonetheless, its structure, two four-stranded beta-sheets forming a flattened beta-barrel, closely resembles that of the lipoyl domain from the pyruvate dehydrogenase multienzyme complex from Bacillus stearothermophilus determined previously. As before, the lipoylation site is physically exposed in a tight turn in one of the beta-sheets, and the N and C-terminal residues are close together at the other end of the molecule in adjacent strands of the other beta-sheet. Another prominently conserved feature of the structure is the 2-fold axis of quasi-symmetry relating the N and C-terminal halves of the domain. Consistent with the high level of sequence similarity between lipoyl domains of 2-oxo acid dehydrogenase multienzyme complexes from many different sources, these results confirm that all lipoyl domains are likely to have closely related structures.
Value of the bulbocavernosus reflex latency versus nerve conduction velocity of the dorsal nerve of penis and penile brachial index was evaluated in HIV-1 infected asymptomatic and symptomatic men with and without an objective evidence of neuropathy. These studies revealed striking results in neuropathic group. Both asymptomatic and symptomatic patients with neuropathy exhibited a significant decrease (P < 0.0005) in the values of the nerve conduction velocity of the dorsal nerve of penis as well as penile brachial index in comparison with the controls of the same age group. However both types of non neuropathic patients showed a non significant difference in the above mentioned parameters with their respective controls. The latency of bulbocavernosus reflex showed no significant difference between the groups and was within the normal limits. A non significant association in the values of the study parameters among asymptomatic and symptomatic patients with and without neuropathy was also observed. These findings suggest an exclusively apparent sexual pathway for the penile dorsal nerve conduction and penile brachial index in both HIV-1 infected asymptomatic and AIDS positive men affected by neuropathic conditions, irrespective of their disease state. We thus conclude that a primary defective neuropathic mechanism may play an etiological role in the pathogenesis of erectile impotence in these patients.
The 51-kDa flavoprotein subunit of mitochondrial NADH:ubiquinone oxidoreductase (Complex I) [NADH dehydrogenase (ubiquinone), flavoprotein 1 (51 kDa); EC 1.6.5.3] plays an important role in the formation of the NADH-binding site and is believed to be the principal site of entry for electrons donated by NADH into the respiratory chain. Human cDNA fragments of the 51-kDa protein were generated by polymerase chain reaction and used to localize the gene (NDUFV1) for this subunit to 11q13 by two separate techniques. This region of the human genome is strongly implicated in a number of different forms of cancer.
The lipoate acyltransferase subunits of the 2-oxo acid dehydrogenase complexes are post-translationally modified with one or more covalently-bound lipoyl cofactors. Two distinct lipoate-protein ligase activities, LPL-A and LPL-B, have been detected in E. coli by their ability to modify purified lipoyl apo-domains of the bacterial pyruvate dehydrogenase complex. Both enzymes require ATP and Mg2+, use L-lipoate, 8-methyllipoate, lipoyl adenylate and octanoyl adenylate as substrates, and both activate lipoyl-deficient pyruvate dehydrogenase complexes. In contrast, only LPL-B uses D-lipoate and octanoate and there are differences in the metal-ion and phosphate requirements. It is suggested that LPL-B may be responsible for the octanoylation of lipoyl domains observed previously under lipoate-deficient conditions.
The dihydrolipoamide acetyltransferase subunit (E2p) of the pyruvate dehydrogenase complex of Escherichia coli has three highly conserved and tandemly repeated lipoyl domains, each containing approx. 80 amino acid residues. These domains are covalently modified with lipoyl groups bound in amide linkage to the N6-amino groups of specific lysine residues, and the cofactors perform essential roles in the formation and transfer of acetyl groups by the dehydrogenase (E1p) and acetyltransferase (E2p) subunits. A subgene encoding a hybrid lipoyl domain was previously shown to generate two products when overexpressed, whereas a mutant subgene, in which the lipoyl-lysine codon is replaced by a glutamine codon, expresses only one product. A method has been devised for purifying the three types of independently folded domain from crude extracts of E. coli, based on their pH-(and heat-)stabilities. The domains were characterized by: amino acid and N-terminal sequence analysis, lipoic acid content, acetylation by E1p, tryptic peptide analysis and immunochemical activity. This has shown that the two forms of domain expressed from the parental subgene are lipoylated (L203) and unlipoylated (U203) derivatives of the hybrid lipoyl domain, whereas the mutant subgene produces a single unlipoylatable domain (204) containing the Lys-244----Gln substitution.
Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease characterized by the presence of antimitochondrial autoantibodies in the serum. The major antigens recognized by the antibodies are the E2 components of the 2-oxo acid dehydrogenase complexes, all of which possess covalently attached lipoic acid cofactors. A bacterial etiology has been proposed for the disease, and patients' antibodies are known to recognize the E2 subunits (E2p) of both mammalian and bacterial pyruvate dehydrogenase complexes. Immunoblotting and ELISA inhibition techniques using extracts of Escherichia coli deletion strains, genetically restructured E2 polypeptides, and isolated lipoyl domains demonstrate that (i) the E2o subunit of the E. coli 2-oxoglutarate dehydrogenase complex is recognized by patients' antibodies; (ii) the main immunogenic region of E2p lies within the lipoly domains; (iii) the presence of a lipoly residue within the domain is crucial for effective recognition by the antibodies; and (iv) octanoylated E2p, octanoylated E2o, and octanoylated lipoyl domain, produced by a mutant deficient in lipoate biosynthesis, are recognized by patients' antibodies but not as effectively as their lipoylated counterparts. These findings indicate that antibodies in PBC patients' sera bind to a unique peptide-cofactor conformation within the lipoyl domains of the E2 polypeptides and that this epitope is partially mimicked by substituting the lipoyl cofactor with an octanoyl group.
The overexpression of a subgene encoding a hybrid lipoyl domain of the dihydrolipoamide acetyltransferase component of the pyruvate dehydrogenase complex of Escherichia coli has previously been shown to result in the formation of lipoylated and unlipoylated products. Overexpression of the same subgene in a lipoic acid biosynthesis mutant growing under lipoate-deficient conditions has now been shown to produce domains modified by octanoylation as well as unmodified domains. It was concluded from the mass of a lipoyl-binding-site peptide that the modification involves N6-octanoylation of the lysine residue (Lys244) that is normally lipoylated, and this was confirmed by the trypsin-insensitivity of the corresponding Lys244-Ala-245 bond, and the absence of modification in a mutant domain in which Lys244 is replaced by Gln. This novel protein modification raises interesting questions concerning the pathway of lipoic acid biosynthesis and the mechanism of enzyme lipoylation.
Diabetic neuropathies were studied in 100 insulin-dependent diabetes mellitus patients, 314 non-insulin-dependent diabetes mellitus patients with and without an objective evidence of neuropathy (age span, 15-80 years; duration of diabetes distributed over 1-33 years), and their age-matched nondiabetic controls. Serum and urinary levels of pituitary-gonadal hormones were evaluated in the diabetic subjects. There were striking results, i.e., a significantly low serum total and serum free (urinary) testosterone level (p < .0005) and a significantly high serum and urinary FSH and LH and serum prolactin level (p < .0005), specifically in the neuropathic diabetic patients, suggesting a series of pathological reactions in the smooth musculature of genital organs characterized by an increase in the interstitial thickness of seminiferous tubules, peritubular and intertubular fibrosis, and tubular sclerosis. Testicular necrosis, probably due to neuropathy, provided an additional aid to confirm these findings. A decrease in semen volume and sperm motility in the diabetic neuropathic patients further suggested the involvement of the entire smooth musculature of the reproductive tract, leading to atonia of the bladder and urethra. Such complications are purely neurogenic. The low serum and urinary testosterone levels and increased serum and urinary FSH and LH and serum prolactin levels in the diabetic men with neuropathy suggest gonadal disorder (hypogonadotropic hypogonadism), which may be due to testicular necrosis and thickening of seminiferous tubules, causing autonomic lesion.
The present study deals with the diabetic neuropathies prevailing in men. In this investigation 100 insulin-dependent diabetes mellitus (IDDM) and 314 non-insulin-dependent diabetes mellitus (NIDDM) patients with and without an objective evidence of neuropathy, having an age span in between 15 and 60 years and a duration of diabetes distributed over 1-33 years, were included along with their age-matched nondiabetic controls. The diabetic subjects were evaluated for the induction of erectile responses. Investigation of induction of erectile responses to erotic stimulation by film and fantasy revealed striking results in diabetic patients with established neuropathy. Both IDDM and NIDDM patients with neuropathy exhibited a highly significant decrease (P < .0005) in penile diameter and length, penile arterial pulse amplitude, both systolic and diastolic blood pressures, and heart rate compared to controls of the same age group. However, both IDDM and NIDDM patients without neuropathy showed a nonsignificant difference in the above-mentioned parameters compared to control subjects. A nonsignificant association of induction of erectile responses to erotic stimulations among IDDM and NIDDM patients with and without neuropathy was also observed, suggesting that impotence and altered erectile responses are likely to be associated with an increased frequency to autonomic neuropathy in these patients irrespective of their type of diabetes.
The present study deals with the diabetic neuropathies prevailing in the male population. In this investigation 100 insulin-dependent diabetes mellitus (IDDM) and 314 non-insulin-dependent diabetes mellitus (NIDDM) patients with and without an objective evidence of neuropathy, having an age span of 15 to 80 years and the duration of diabetes distributed over 1-33 years were included along with age-matched nondiabetic controls. The diabetic subjects were evaluated for semen analysis. Results of semen analysis showed a highly significant increase (p > .0005) in total sperm output and sperm concentration in both IDDM and NIDDM neuropathic diabetic men. On the other hand, sperm motility and semen volume were found to be about 30 and 60% less, respectively, in IDDM and NIDDM patients, where as sperm morphology and quality of sperm motility remained unaffected. A comparison between IDDM and NIDDM neuropathic and non-neuropathic diabetic groups further indicated a nonsignificant difference in the parameters of semen analysis, thus suggesting an endocrine basis for the sexual disturbances of diabetic neuropathy. A significant rise in total sperm output in both IDDM and NIDDM neuropathic diabetic patients and a significant decrease in semen volume in both types of diabetic patients thus suggests some kind of Leydig cell hyperplasia, which in turn may stimulate spermatogenesis and atonia of the bladder and urethra, resulting in retrograde ejaculation.
Value of the residual urine index was evaluated in 40 individuals both insulin-dependent (IDDM) and non-insulin dependent (NIDDM) diabetic male patients with and without an objective evidence of neuropathy and in 20 age matched non-diabetic men serving as controls using post void bladder ultrasonographic technique. These studies revealed striking results in the neuropathic group. Both IDDM and NIDDM diabetic patients with neuropathy exhibited a significant (P < 0.005) increase in residual-volume in comparison with the controls of the same age group and a direct correlation between residual urine retention and neurogenic bladder was found to be established thus suggesting a generalized massive hypotonia of the bladder in these patients. However, non of the two types of non-neuropathic diabetic patients showed significant difference in the above-mentioned parameters compared to that their respective controls. A non-significant association in the values of the study parameters between insulin dependent and non-insulin dependent diabetic men (with and without neuropathy) was also observed. These findings thus suggest a probable neuropathic involvement in the pathway of urinary tract in both IDDM and NIDDM diabetic men with neuropathy. The greater impairment of the values of residual urine index in these patients may be due to overall greater severity of neuropathy with sympathetic as well as parasympathetic damage irrespective of their type of diabetes.