Biomedical subjects

M S Patel

Publications and source records attributed to M S Patel.

At least 109 records · Page 6Linked to original sources

PubMed1992

Artificial-rearing technique: its usefulness in nutrition research.

The rat model has been useful in determining the role of nutrients in such mammalian developmental processes as maturation of the brain and gastrointestinal tract and metabolic adaptation in the liver. The suckling period, a critical time in early development, has been intractable to classical nutritional studies because of the necessity of the maternal involvement in rearing the pups. In this article, we review a promising technique in which rat pups are artificially reared through the use of an intragastric cannula connected to an automated pump that delivers a milk-substitute formula. We present relevant details of this technique, highlighting some of its advantages and limitations. Three metabolic processes in different organs are presented as examples of the usefulness of the artificial-rearing technique. This technique has high potential for a wider range of applications in nutritional assessment of macro- and micronutrients and in metabolic regulation in rats during the early postnatal period.

Animals↗

PubMed1992

A mutation in the E1 alpha subunit of pyruvate dehydrogenase associated with variable expression of pyruvate dehydrogenase complex deficiency.

Defects in pyruvate dehydrogenase, the first catalytic component of the pyruvate dehydrogenase complex, are the most common cause of pyruvate dehydrogenase complex deficiency. A family with variable pyruvate dehydrogenase complex deficiency had been described in which cultured skin fibroblasts of affected family members had normal pyruvate dehydrogenase complex activity, but different tissues and blood lymphocytes had significantly diminished activities. Enzymatic activity and immunoblot studies indicated that pyruvate dehydrogenase was affected. Further evidence is presented here showing that the defect affecting pyruvate dehydrogenase complex activity is posttranscriptional. Sequencing of the coding region of the alpha-subunit of pyruvate dehydrogenase revealed a point mutation in the codon for amino acid 234 resulting in a substitution of glycine for arginine. Study of other members of the family suggested that this mutation is inherited in a sex-linked mode. The point mutation is located in a highly conserved region of the pyruvate dehydrogenase alpha-subunit gene that contains both hydrophobic and positively charged amino acid residues. Variable expression of pyruvate dehydrogenase complex deficiency in this case may be due to instability of the pyruvate dehydrogenase heterotetramer in specific tissues because of a disruption in subunit-subunit interaction.

Amino Acid Sequence↗

PubMed1991

Frequent hospital admissions for bacterial infections among aboriginal people with diabetes in central Australia.

OBJECTIVE: To determine hospital-based morbidity and mortality from bacterial infections among Aboriginal people with diabetes in central Australia. DESIGN: Examination of medical records on diabetic inpatients between January 1984 and December 1986. SETTING: Alice Springs Hospital in central Australia, covering an Aboriginal population of about 12,500 people. PATIENTS: Subjects admitted with a bacterial infection (n = 165) were selected from the database of all Aboriginal people known to have diabetes in the region (n = 374; all had non-insulin dependent diabetes). MAIN OUTCOME MEASURES: Number of admissions, type and site of infections, causative organisms, duration of hospital stay and cause of death. RESULTS: The 281 admissions for infections accounted for 4.6% of adult Aboriginal admissions to hospital. Thirteen patients died. Eleven patients required amputation of a digit or limb. In 1986, 13/200 patients admitted with diabetes had bacteraemia compared with 14/1885 patients who did not have diabetes. One patient had Fournier's gangrene, one had malignant otitis externa, one community acquired Acinetobacter pneumonia, one pneumonia with Succinivibrio spp. found in blood cultures, and one meningitis and transverse myelopathy with Streptococcus milleri found in blood cultures. CONCLUSIONS: The frequency, type and severity of infections in the relatively young patients result in high personal costs to the community and financial costs to the health care system. Standard preventive measures must be implemented to control severe bacterial infections among subjects with diabetes in this socially and economically marginalised population group.

Adult↗

PubMed1991

Expression of cDNA sequences encoding mature and precursor forms of human dihydrolipoamide dehydrogenase in Escherichia coli. Differences in kinetic mechanisms.

The cDNA sequences encoding mature and precursor forms of human dihydrolipoamide dehydrogenase (E3) were expressed in Escherichia coli using a lambda PL promoter-driven prokaryotic expression vector. The expressed proteins in total cell extracts were identified by Western blot analysis using anti-pig heart E3 antibody and also by measurement of E3 activity. Most of the expressed human E3 polypeptides (five bands) were found in the insoluble pellet while primarily full-length mature E3 was found in the soluble fraction. About 2% of the total soluble protein was mature human E3 when expressed in wild type E. coli AR120. Since wild type E. coli has its own endogenous E3 activity, the expression of human E3 was performed in a pyruvate dehydrogenase complex-deficient strain of E. coli, JRG1342. The expressed recombinant human E3s in JRG1342 were purified to near homogeneity. The amino-terminal amino acid sequence analysis revealed that the recombinant mature E3 had an expected sequence while the recombinant precursor E3 lost 19 amino acid residues of its 35-amino acid leader sequence presumably due to a proteolytic cleavage. The recombinant mature E3 displayed comparable kinetic properties to those reported for highly purified mammalian E3s. The truncated precursor E3 showed about half of the mature E3 activity. The double-reciprocal plot for the mature E3 in the direction of NAD+ reduction showed parallel lines (ping-pong mechanism) while that for the truncated precursor E3 displayed intersecting lines (sequential mechanism). In the direction of NADH oxidation, the kinetic mechanisms of both E3s were apparently a ping-pong mechanism. These kinetic results showed that the partial 16-amino acid extension in the leader sequence changed the kinetic mechanism of human E3 so that it resembled that of glutathione reductase.

Amino Acid Sequence↗

PubMed1991

Sequence conservation in the alpha and beta subunits of pyruvate dehydrogenase and its similarity to branched-chain alpha-keto acid dehydrogenase.

Amino acid sequence comparison of 8 alpha and 6 beta subunits of the alpha-keto acid dehydrogenase (E1) component of the pyruvate dehydrogenase complex and branched-chain alpha-keto acid dehydrogenase complex form multiple species was performed by computer analysis. In addition to 2 previously recognized regions of homology in the alpha subunit, a 3rd region of extensive homology was identified in E1 alpha, and may be one of the sites involved in subunit interaction. E1 beta contains 4 regions of extensive homology. Region 1 contains 10 amino acids that are homologous to a 10-amino acid stretch in Escherichia coli E1. Regions 2 and 3 have sequence homologies with other dehydrogenases suggesting that these regions may be involved in catalysis.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗

PubMed1991

Regulation of human growth hormone receptor gene expression by human growth hormone in a human hepatoma cell line.

We have investigated the effects of recombinant human growth hormone (r-hGH) on the expression of hGH-receptor in a human hepatoma cell line (HuH 7). Levels of hGH-receptor mRNA in HuH 7 cells treated with different doses of r-hGH were measured by means of an RNase protection assay. Treatment with r-hGH at physiological concentrations (12.5, 25 and 50 ng/ml) resulted in an increase in hGH-receptor mRNA levels within 1 h of addition of the hormone. A steady state was reached after 3-4 h and maintained for at least 48 h. In contrast, treatment with supraphysiological r-hGH concentrations (150 and 500 ng/ml) led to a down-regulation of hGH-receptor mRNA levels during the first 3 h after hormone addition followed by an increase in hGH-receptor mRNA levels thereafter. Nuclear run-off assays demonstrated that these changes in hGH-receptor mRNA levels were a result of changes in the rate of transcription of the hGH-receptor gene. Cycloheximide (10 micrograms/ml) did not affect these changes in hGH-receptor gene transcription significantly, indicating that they are mediated by pre-existing factors and do not require new protein synthesis. These data demonstrate that r-hGH specifically regulates the rate of transcription of the hGH-receptor gene in a human hepatoma cell line.

Blotting, Northern↗

PubMed1991

Specific reactivity of recombinant human PDC-E1 alpha in primary biliary cirrhosis.

The mitochondrial autoantigens recognized by autoantibodies in patients with primary biliary cirrhosis have been identified as components of related multi-enzyme complexes, including acyltransferases of the pyruvate dehydrogenase complex (PDC), the branched-chain alpha-keto acid dehydrogenase complex (BCODH), the alpha-ketoglutarate dehydrogenase complex (OGDC), protein X and pyruvate dehydrogenase (PDC) E1 alpha and E1 beta. The major autoantigens, PDC-E2, BCODH-E2 and OGDC-E2, share some sequence homology; the epitopes on these antigens appear to be close to, or identical with, the lipoic acid binding site. Furthermore, all three antigens share some structural homology. In contrast, antibodies to PDC-E1 alpha are present in lower titers, and have been more difficult to detect. PDC-E1 alpha also differs from the three major autoantigens in that it lacks any covalently bound lipoic acid. PDC-E1 alpha cannot be purified in large quantities and becomes unstable in the absence of PDC-E1 beta. To address these problems, we have subcloned recombinant human PDC-E1 alpha to pGEX, pGEX is a vector which produces a recombinant polypeptide fused to glutathione S-transferase. The resultant E1 alpha fusion protein is stable and has a low background in immunoassays. Using the recombinant protein, we have developed an ELISA that allows rapid and reproducible quantification of antibodies to human PDC-E1 alpha. Finally, we demonstrate that a major epitope on PDC-E1 alpha is within a 300 amino acid region that contains the enzyme functional sites, namely the phosphorylation site and the TPP binding site.

Autoantibodies↗

PubMed1991

Growth characteristics and response to growth hormone therapy in patients with hypochondroplasia: genetic linkage of the insulin-like growth factor I gene at chromosome 12q23 to the disease in a subgroup of these patients.

Hypochondroplasia, a heterogeneous and usually mild form of chondrodystrophy, is a common cause of short stature. It often goes unrecognized in childhood and is diagnosed in adult life when disproportionate short stature becomes obvious. We performed restriction enzyme analysis of the insulin-like growth factor I (IGF-I) gene on the families of 20 white British Caucasian children with short stature attributed to hypochondroplasia by radiological and clinical criteria, who were undergoing human growth hormone (r-hGH) treatment, in 60 children with isolated growth hormone deficiency and in 50 normal individuals. The frequency of the heterozygous pattern (Hind III: 8.2, 5.2, 4.8, 3.2 kb fragments, Pvu: 8.4, 5.1, 4.7, 2.5 kb fragments) in children with hypochondroplasia was significantly higher (chi2: P less than 0.05) than in the control groups. The hypochondroplastic children whose response to r-hGH treatment was characterized by a proportionate increase in both spinal and subischial leg length were all heterozygous for two co-inherited IGF-I gene restriction fragment length polymorphism (RFLP) alleles (Hind III: 5.2, 4.8 kb; Pvu II: 5.1, 4.7 kb). Children whose response was characterized by accentuation of the body disproportion by r-hGH treatment were all homozygous for these alleles (Hind III: 4.8, 4.8 kb; Pvu II: 4.7, 4.7 kb). Their response to r-hGH treatment is significantly different (P less than 0.01). Studies of the families of the heterozygous affected children demonstrated strong linkage (lod score 3.311 at zero recombination) of the IGF-I gene locus at chromosome 12q23 to this subgroup of hypochondroplasia. The 5.2 kb Hind III and 5.1 kb Pvu II alleles are in strong linkage disequilibrium with this trait. These data indicate that IGF-I gene may be a candidate gene for involvement in the aetiology of short stature presenting with hypochondroplastic features and a proportionate response to r-hGH treatment; they also provide support for the concept of genetic heterogeneity in chondrodystrophy.

Achondroplasia↗

PubMed1991

Constitutionally short stature: analysis of the insulin-like growth factor-I gene and the human growth hormone gene cluster.

It has been suggested that modifications of the IGF-I gene might be responsible for constitutionally short stature (CSS). To assess this possibility, and to examine the possible role of the hGH gene cluster in CSS, we used Southern blotting and restriction fragment length polymorphism (RFLP) linkage analysis to study 57 children with CSS, including 17 children from 10 families with CSS. We studied as control populations 50 children and 25 adults of normal height, including three families, and 60 children with isolated growth hormone deficiency. No gross structural abnormalities of the IGF-I gene or the hGH gene cluster were found in any of the subjects. The allelic frequencies for each of two distinct RFLP associated with the IGF-I gene (EcoRV and HindIII/PvuII) and for each of five distinct RFLP associated with the hGH gene cluster [BglII(A), BglII(B), MspI(A), MspI(B), and HincII] were the same in the CSS, isolated growth hormone deficiency, and normal populations, and the RFLP haplotypes for both the IGF-I gene and the hGH gene cluster also appeared with the same frequency in all three populations. Analysis of the families that contained heterozygotes for the HindIII/PvuII and/or EcoRV IGF-I RFLP excluded a linkage of the IGF-I gene to CSS in these families. Assuming that the inheritance is dominant, the lod score at 1% recombination was -2.2, whereas assuming a recessive inheritance, the lod score at 1% recombination was -1.93.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Southern↗

PubMed1990

Diabetes among aboriginal people in central Australia: a high prevalence based on health service attendance.

The prevalence of diagnosed diabetes in Aboriginal people living in central Australia (population, 9983) was determined by collating data from the hospital, rural and urban health services, nursing homes and death registers. A total of 98 male and 183 female Aboriginal residents with diabetes attended health services in central Australia between January 1984 and December 1986. The point prevalence of diagnosed diabetes at the end of 1986 in the age group 25-34 years was 1.6% in men and 3.1% in women, and in those over 35 years, 8.8% and 14.1%, respectively. The true prevalence of diabetes (diagnosed and undetected) is likely to be at least twice this rate, and constitutes a major public health problem in central Australia. Diabetes and other disorders such as obesity, hypertension and ischaemic heart disease have common antecedents and outcomes. The control of these non-communicable diseases requires integrated and culturally appropriate educational, social and medical strategies.

Adolescent↗

PubMed1990

Acute rheumatic fever and rheumatic heart disease in a rural central Australian aboriginal community.

A retrospective study of clinical case records was conducted at the health centre of a rural central Australian Aboriginal community to determine the frequency of acute rheumatic fever and of rheumatic heart disease between 1978 and 1987. The case records of 976 residents over 5 years of age were examined for evidence of the clinical indicators of acute rheumatic fever or rheumatic heart disease; together they contributed 8015 person-years of study. During the 10-year study period, 18 patients developed acute rheumatic fever and 12 patients had rheumatic heart disease. The annual incidence of acute rheumatic fever (first and recurrent attacks) for children aged 5-14 years was 815 per 100,000 person-years. For the residents aged 5 years and over, the point prevalence for rheumatic heart disease at the end of 1987 was between 7.9 and 12.3 per 1000 persons, according to health clinic records and the official population census, respectively. These rates are similar to those reported for Third World countries. Preventive measures must include efforts by health professionals to help to alleviate the adverse living conditions in Aboriginal communities.

Acute Disease↗

PubMed1990

Cloning and cDNA sequence of the beta-subunit component of human pyruvate dehydrogenase complex.

Two cDNA clones (lambda E1 beta 1, 1469 bp; lambda E1 beta 12, 1437 bp) encoding the beta-subunit of the pyruvate dehydrogenase (E1) component of the human pyruvate dehydrogenase complex were isolated from a human liver lambda gt11 cDNA library. The composite human liver E1 beta cDNA encoded the entire mature E1 beta [329 amino acids (aa)] as well as a portion (26 aa) of the E1 beta leader peptide. Significant discrepancies were identified between the nucleotide and deduced aa sequences of human liver E1 beta cDNAs and the corresponding sequences of a previously reported cultured human foreskin fibroblast E1 beta cDNA [Koike et al., Proc. Natl. Acad. Sci. USA 85 (1988) 41-45]. The composite human liver E1 beta cDNA generated in this study provides a reference sequence for investigating the structure-function relationship of human E1 beta and for characterizing genetic mutations in patients with E1 deficiency.

Amino Acid Sequence↗

PubMed1990

Molecular biology and biochemistry of pyruvate dehydrogenase complexes.

In most organisms, the pyruvate dehydrogenase complex catalyzes the pivotal irreversible reaction that leads to the consumption of glucose in the aerobic, energy-generating pathways. A combination of biochemical and molecular biology studies have greatly expanded our understanding of the overall structural organization of this multicomponent system, delineated the locations and elucidated the functions of structural domains of the catalytic components, and revealed significant evolutionary changes. Important to this progress was the deduction of the primary amino acid sequences from cDNA clones for each of the catalytic components from several species. The greatest detail is available for the FAD-containing dihydrolipoamide dehydrogenase component, which is the only component for which tertiary structure information has recently emerged. For the dihydrolipoamide acetyltransferase core component, a similar but species-variable multidomain structure is established that is responsible for the distinct architectures of the inner cores, the peripheral binding of the other components, and the conveyance of reaction intermediates between distantly separated active sites. A second lipoyl-bearing component, protein X, has been shown to play a critical role in the organization and function of the complex from many higher organisms. Although much is known about the means of effector modulation of mammalian complex activity, identification of the signal eliciting its regulation by insulin still poses an exciting challenge.

Amino Acid Sequence↗

PubMed1989

Ochratoxin A decreases the activity of phosphoenolpyruvate carboxykinase and its mRNA content in primary cultures of rat kidney proximal convoluted tubule cells.

The effect of ochratoxin A on the specific activities of phosphoenolpyruvate carboxykinase, gamma-glutamyl transpeptidase and phosphate-dependent glutaminase were investigated in primary cultures of rat kidney proximal convoluted tubule cells grown in a serum-free medium supplemented with growth factors. Addition of ochratoxin A (25-100 microM) to the medium caused reduction in the specific activities of phosphoenolpyruvate carboxykinase and gamma-glutamyl transpeptidase only. Addition of cAMP caused a four-fold increase in the concentration of phosphoenolpyruvate carboxykinase mRNA in tubule cells within 3 h. This cAMP-mediated increase in phosphoenolpyruvate carboxykinase mRNA content was abolished when ochratoxin A was added simultaneously.

Animals↗

PubMed1989

Dihydrolipoamide dehydrogenase: functional similarities and divergent evolution of the pyridine nucleotide-disulfide oxidoreductases.

Dihydrolipoamide dehydrogenase (E3) is the common component of the three alpha-ketoacid dehydrogenase complexes oxidizing pyruvate, alpha-ketoglutarate, and the branched-chain alpha-ketoacids. E3 also participates in the glycine cleavage system. E3 belongs to the enzyme family called pyridine nucleotide-disulfide oxidoreductases, catalyzing the electron transfer between pyridine nucleotides and disulfide compounds. This review summarizes the information available for E3 from a variety of species, from a halophilic archaebacterium which has E3 but no alpha-ketoacid dehydrogenase complexes, to mammalian species. Evidence is reviewed for the existence of two E3 isozymes (one for pyruvate dehydrogenase complex and alpha-ketoglutarate dehydrogenase complex and the other for branched-chain alpha-ketoacid dehydrogenase complex) in Pseudomonas species and for possible mammalian isozymes of E3, one associated with the three alpha-ketoacid dehydrogenase complexes and one for the glycine cleavage system. The comparison of the complete amino acid sequences of E3 from Escherichia coli, yeast, pig, and human shows considerable homologies of certain amino acid residues or short stretches of sequences, especially in the specific catalytic and structural domains. Similar homology is found with the limited available amino acid sequence information on E3 from several other species. Sequence comparison is also presented for other member flavoproteins [e.g., glutathione reductase and mercury(II) reductase] of the pyridine nucleotide-disulfide oxidoreductase family. Based on the known tertiary structure of human glutathione reductase it may be possible to predict the domain structures of E3. Additionally, the sequence information may help to better understand a divergent evolutionary relationship among these flavoproteins in different species.

Amino Acid Sequence↗

PubMed1989

Bacterial infections among patients with diabetes in Papua New Guinea.

This study reports the morbidity that resulted from bacterial infections in Melanesian patients with non-insulin-dependent diabetes who attended the Port Moresby General Hospital, Papua New Guinea, between January 1, 1982 and June 30, 1984. Fifty-three of 160 patients with diabetes experienced 66 episodes of infection, 48 of which required inpatient hospital treatment. The average length of stay in hospital was 37.6 days per episode of infection. Of 88 patients who were newly-diagnosed as diabetic during this period, 30 patients initially had presented with a bacterial infection. The lower limb was the site that was infected most frequently, and Staphylococcus aureus and Klebsiella pneumoniae were the usual causative organisms. Eleven patients had bacterial gangrene of the foot; two of these patients were less than 23 years of age, and five patients were not known to have had diabetes previously. Five patients were suffering from pulmonary tuberculosis; the annual incidence of tuberculosis in this study group (12.5 cases/1000 patients) was about 11-times higher than that which has been reported for the general population. Thirteen patients with diabetes died in hospital during the study period. Infection was the cause of death in nine patients and three of these patients were less than 25 years of age. The morbidity of infection can be controlled if diabetes is sought more frequently in patients with infections, and if glycaemia can be controlled. This will have to be achieved through existing primary health-care structures, as resources for diabetes-specific preventive programmes in developing countries will be limited.

Adult↗

PubMed1989

An introduction to meta-analysis.

The current rapid pace of social and technological change requires health policy makers to be up to date in their knowledge of health policy research. The "information explosion" has created a need for techniques that synthesize and summarize available information. This paper reviews the use of Meta-Analysis as a data pooling technique in a non-technical manner. Treatment of chronic pain by acupuncture, provided as an example, illustrates the type of information that can be obtained from a Meta-Analysis, that is not conventionally available from individual trials.

Health Policy↗

PubMed1989

Characterization of cDNAs encoding human pyruvate dehydrogenase alpha subunit.

A cDNA clone (1423 base pairs) comprising the entire coding region of the precursor form of the alpha subunit of pyruvate dehydrogenase (E1 alpha) has been isolated from a human liver cDNA library in phage lambda gt11. The first 29 amino acids deduced from the open reading frame correspond to a typical mitochondrial targeting leader sequence. The remaining 361 amino acids, starting at the N terminus with phenylalanine, represent the mature mitochondrial E1 alpha peptide. The cDNA has 43 base pairs in the 5' untranslated region and 210 base pairs in the 3' untranslated region, including a polyadenylylation signal and a short poly(A) tract. The nucleotide sequence of human liver E1 alpha cDNA was confirmed by the nucleotide sequences of three overlapping fragments generated from human liver and fibroblast RNA by reverse transcription and DNA amplification by the polymerase chain reaction. This consensus nucleotide sequence of human liver E1 alpha cDNA resolves existing discrepancies among three previously reported human E1 alpha cDNAs and provides the unambiguous reference sequence needed for the characterization of genetic mutations in pyruvate dehydrogenase-deficient patients.

Amino Acid Sequence↗