PubMed Health⌕ Search

Biomedical subjects

A Saha

Publications and source records attributed to A Saha.

At least 19 recordsLinked to original sources
PubMed1992

Teaching clinical skills to new medical students: the Oman experience.

The College of Medicine at the Sultan Qaboos University (SQU) in Oman took up the challenge of moving away from a didactic emphasis in the teaching of family and community health by actively involving students in health care, requiring some clinical skills, as early as possible. This paper describes the experience of the Department of Family and Community Health at SQU of the feasibility of training first-year medical students in the measurement of blood pressure within a few days. Our experience showed that proper training before starting field-work can teach clinical skills to students who have had no prior exposure to medical subjects. There was a strong correlation between the measurements of blood pressure of 638 individuals by the students and the supervisors. This experience at SQU has encouraged us to implement the idea of family- and community-based clinical exposure for every class. Teaching of clinical skills is feasible in the field for new entrants, provided there is adequate orientation beforehand and skilled supervision of the students in small groups.

Clinical Competence↗
PubMed1992

Education in family and community health: the challenge faced by a new medical school.

This paper describes the efforts of the Department of Family and Community Health at Sultan Qaboos University in providing opportunities for the development of 'hands-on' problem-solving skills appropriate for Oman. The curriculum of the Department is discussed, highlighting the unusual emphasis of this discipline in both the preclinical and clinical curriculum of the College of Medicine. The importance of continuous assessment and supervision of students is discussed. Course-work in the preclinical curriculum of the Department is kept to a minimum. Field-work forms an important part of preclinical training, where application and problem-based learning are emphasized. During the clinical years the students are exposed to an integrated series of lectures and practicals covering core knowledge in clinical medicine. Practical clinical training, over a total period of 15 weeks, takes place at a variety of sites where common problems in primary health care in Oman are handled by students under supervision.

Clinical Competence↗
PubMed1992

Radiation-induced inactivation of dihydroorotate dehydrogenase in dilute aqueous solution.

The inactivation of dihydroorotate dehydrogenase by gamma irradiation in dilute aqueous solution has been investigated. The activity of the enzyme decreased exponentially as a function of the absorbed dose under aerated and nitrous oxide-saturated conditions. The contributions of the individual radical species derived from water radiolysis were estimated from the inactivation results observed under aerated, argon-saturated, and nitrous oxide-saturated conditions. The hydrogen atom and hydroxyl radical were found to be important in enzyme inactivation. The effect of selected inorganic radical anions such as Br.2-, I.2-, and (SCN).2- on the enzyme activity was also studied, and the results implicate the possible involvement of cysteine and tyrosine residues in the catalytic activity of dihydroorotate dehydrogenase. Changes in the kinetic parameters (Michaelis-Menten constant, Km, and maximal velocity, Vmax) due to irradiation under the conditions investigated suggest that radiation-induced inactivation is due to modification of the substrate binding sites and that of the active site residues in the enzyme. Evidence for the reduction of iron-sulfur centers in the enzyme during the inactivation process has been put forward from the difference spectrum of the irradiated dihydroorotate dehydrogenase. It has also been shown by electrophoretic studies that radiation-induced inactivation was not due to any fragmentation of the protein structure or the formation of any intermolecular crosslinking.

Cobalt Radioisotopes↗
PubMed1991

Radiation-induced changes in flavin fluorescence of dihydroorotate dehydrogenase.

The effect of gamma-radiation on the flavin moiety of dihydroorotate dehydrogenase was studied by fluorescence spectroscopy. Irradiation of aerated solutions (0-7 Gy) led to a small increase in fluorescence intensity, but with higher doses a decrease in intensity was observed. The increase in fluorescence intensity after irradiation at low doses may be attributed to protein unfolding, leading to greater exposure of flavin groups and a concomitant increase in separation between the flavin moiety and the iron-sulphur centre. This was confirmed by fluorescence quenching studies using potassium iodide as quencher. The Stern-Volmer constant calculated for iodide quenching indicates a two-fold increase in the fraction of flavin moiety being accessible to the quencher after 6.6 Gy. No spectral change was observed when unirradiated or irradiated enzyme was denatured with guanidine hydrochloride. However, a decrease in fluorescence intensity in the case of irradiated samples indicated a radiation-induced decrease in the flavin fluorophore. The flavin fluorophore loss in dihydroorotate dehydrogenase was also determined using aerated, argon-saturated or nitrous oxide-saturated solutions. H and OH radicals were found to have nearly equal contributions in damaging the flavin moiety of dihydroorotate dehydrogenase.

Cobalt Radioisotopes↗
PubMed1989

Cysteinyl peptide labeled by 3-bromo-2-ketoglutarate in the active site of pig heart NAD+-dependent isocitrate dehydrogenase.

The substrate affinity label 3-bromo-2-ketoglutarate (BrKG) reacts covalently with pig heart NAD+-specific isocitrate dehydrogenase with complete inactivation and incorporation of about 0.8 mol of reagent/mol of average enzyme subunit [Bednar, R.A., Hartman, F.C., & Colman, R.F. (1982) Biochemistry 21, 3681-3689]. Protection against inactivation is provided by isocitrate and Mn2+. We have now identified a critical modified peptide by comparison of the peptides labeled by BrKG at pH 6.1 in the absence and presence of isocitrate and Mn2+. Modified enzyme, isolated from unreacted BrKG, was incubated with [3H]NaBH4 to reduce the keto group of protein-bound 2-ketoglutarate and thereby introduce a radioactive tracer into the modified amino acid. Following carboxymethylation and digestion with trypsin, the specific modified peptide was isolated by reverse-phase HPLC, first in 0.1% trifluoroacetic acid with a gradient in acetonitrile and then in 20 mM ammonium acetate, pH 5.8, with an acetonitrile gradient. Gas-phase sequencing gave the modified peptide: Ser-Ala-X-Val-Pro-Val-Asp-Phe-Glu-Glu-Val-Val-Val-Ser-Ser-Asn-Ala-Asp-Gl u-Glu- Asp-Ile-Arg. The corresponding tryptic peptide that was isolated from unmodified enzyme yielded the same sequence except for (carboxymethyl)cysteine at position 3, suggesting that cysteine is the target of 3-bromo-2-ketoglutarate. Pig heart NAD+-dependent isocitrate dehydrogenase is composed of three distinct subunits (alpha, beta, and gamma) that can be separated by chromatofocusing in urea and identified by analytical gel isoelectric focusing. The peptide modified by 3-bromo-2-ketoglutarate, which is in or near the substrate site, is derived only from the separated gamma subunit.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1989

Socio-biological correlates of bacteriuria in Saudi pregnant women.

Prevalence and socio-biological correlates of bacteriuria in Saudi pregnant women were investigated at King Fahd Hospital of the University, Al-Khobar, Saudi Arabia. Midstream sample specimens of urine were used for identification of significant bacteriuria (greater than or equal to 10.5 organisms of single species per milliliter of urine). The prevalence of bacteriuria was found to be 14.2%. It was more common in women below 20 years of age and among the parous as against the nullipara women. Bacteriuria was significantly associated with socio-economic conditions. It was higher in those with a low family income, of large family size (10+) and living in over-crowded conditions. Only one-fourth (25.8%) of bacteriuric women were symptomatic. Almost half (45.8%) had a past history of urinary tract infection. To identify the problem of urinary tract infection in a vulnerable group of women, as well as to reduce the load on laboratory facilities, it is suggested that routine antenatal screening for bacteriuria should be advocated on a selective basis, i.e. for the young teenage parous women, those coming from disadvantaged socio-economic conditions and in patients with a past history of urinary tract infection.

Adult↗
PubMed1988

Modification of NAD-dependent isocitrate dehydrogenase by the 2',3'-dialdehyde derivatives of NAD, NADH, NADP, and NADPH.

The 2',3'-dialdehyde nicotinamide ribose derivatives of NAD (oNAD) and NADH (oNADH) have been prepared enzymatically from the corresponding 2',3'-dialdehyde analogs of NADP and NADPH. Pig heart NAD-dependent isocitrate dehydrogenase requires NAD as coenzyme but binds NADPH, as well as NADH, ADP, and ATP, at regulatory sites. Incubation of 1-3 mM oNAD or oNADH with this isocitrate dehydrogenase causes a time-dependent decrease in activity to a limiting value 40% that of the initial enzyme, suggesting that reaction does not occur at the catalytic coenzyme site. Upon varying the concentration of oNAD or oNADH from 0.2 to 3 mM, the inactivation rate constants increase in a nonlinear manner, consistent with reversible binding of oNAD and oNADH to the enzyme prior to covalent reaction. Inactivation is accompanied by incorporation of radioactive reagent with extrapolation to 0.54 mol [14C]oNAD or 0.45 mol [14C]oNADH/mol average enzyme subunit (or about 2 mol reagent/mol enzyme tetramer) when the enzyme is maximally inactivated; this value corresponds to the number of reversible binding sites for each of the natural ligands of isocitrate dehydrogenase. The protection against oNAD or oNADH inactivation by NADH, NADPH, and ADP (but not by isocitrate, NAD, or NADP) indicates that reaction occurs in the region of a nucleotide regulatory site. In contrast to the effects of oNAD and oNADH, oNADP and oNADPH cause total inactivation of the NAD-dependent isocitrate dehydrogenase, concomitant with incorporation, respectively, of about 3.5 mol [14C]oNADP or 1.3 mol [14C]oNADPH/mol average subunit. Reaction rates exhibit a linear dependence on [oNADP] or [oNADPH] and protection by natural ligands against inactivation is not striking. These results imply that oNADP and oNADPH are acting in this case as general chemical modifiers and indicate the importance of the free adenosine 2'-OH of oNAD and oNADH for specific labeling of the NAD-dependent isocitrate dehydrogenase. The new availability of 2',3'-dialdehyde nicotinamide ribose derivatives of NAD, NADH, NADP, and NADPH may allow selection of the appropriate reactive coenzyme analog for affinity labeling of a variety of dehydrogenases.

Adenosine Diphosphate↗
PubMed1979

Conformational stability of a human cryoglobulin.

Studies on a single component human cryoimmunoglobulin (cryo-IgG) (gamma 1 : lambda, Gm 4) were undertaken to gain a better understanding of the conformational stability of macromolecular interfaces essential for self-association of cryo-IgG leading to the formation of visible gel mass. Changes in the gross and localized conformation of cryo-IgG and a monoclonal IgG (gamma 1 : lambda, Gm 4) isolated from a myeloma patient (Hy) (Hy IgG) (gamma 1 : lambda, Gm 4) in alkaline media were determined by analytical ultracentrifugation, fluorescence characteristics, tyrosine ionization and H+ titration. Ultracentrifugal studies revealed that major transition in gross conformation took place at pH 11.4 for cryo-IgG and pH 11.7 for Hy IgG, whereby the number of charges and tyrosine residues exposed to aqueous environment was 110 and 26 for cryo-IgG, and 111 and 48 for Hy IgG, respectively. Beyond this transition pH fragmentation of both the proteins occurred and cryo-IgG lost its capacity for gel formation. Self-association of cryo-IgG was observed upto pH 11.4 in decreasing order with increase in denaturation pH. Cryo-IgG renatured from exposure to higher alkaline pH upto pH 11.4, showed the capability for forming gel, in spite of the irreversible local conformational changes as established by direct and reverse fluorimetric titration and tyrosine ionization studies. Cryo-IgG could be maintained in the optically clear sol phase at pH 10.5, at which pH 12 out of 62 tyrosine residues became exposed to aqueous media. There are distinct differences in the accessibility of tyrosine residues of cryo-IgG and Hy IgG as reflected in their tyrosine ionization profiles.

Cryoglobulins↗
PubMed1978

Study of "spontaneous" abortion in Thailand.

This analysis includes data on 3 530 patients with septic or incomplete, inevitable or threatened abortions who were treated at the Siriraj Hospital in Bangkok between January 1972 and December 1973. Data on the patients' socio-demographic characteristics; their reproductive, abortion, and medical histories; their pre- and postabortion contraceptive acceptance; and a clinical profile of their abortion treatment, including procedure time, length of hospitalization, and immediate and delayed postoperative complications are analyzed.

Abortion, Incomplete↗
PubMed1977

A new look at an old technique: sterilization by infundibulectomy.

Removal of the fimbriated portion of the fallopian tube is, theoretically, quite an effective method of sterilization that has received scant attention in the recent medical literature. In this study 310 cases of infundibulectomy via laparotomy performed at the Castle Street Hospital for Women in Colombo, Sri Lanka, were analyzed. Most of the patients (88.4%) were sterilized within 10 days of the vaginal term delivery whereas the remainder were sterilized in the immediate postabortion period. General anesthetic was used in 93.9% of the procedures. Difficulties at surgery which prevented infundibulectomy were encountered in three cases (1.1%). Infection and other incision problems were the primary complications. Incision infection was noted prior to discharge in four postpartum cases (1.5%) and in no postabortion cases. At the time of the first follow-up visit, seven to 21 days after sterilization, this complication was noted in eight postpartum women (3.1%) and in one woman (2.8%) who had had an abortion. No pregnancies have been reported among the 169 patients who have already been seen at the six-month follow-up visit. The results of this study indicate that infundibulectomy is a safe and effective method of tubal occlusion for postpartum patients.

Adult↗
PubMed1976

Female sterilization via minilaparotomy.

A simple, safe, economical and potentially reversible technique for female sterilization via minilaparotomy is evaluated in 204 patients (not recently pregnant and postpartum). Only light general anesthesia is required, and the procedure is performed with only equipment normally available in any hospital or outpatient clinic. A 2cm circumumbilical or suprapubic incision is made, and the physician manipulates the uterus to bring the fallopian tube in line with the incision. As the cornu passes the incision, the release of intraabdominal pressure at the site of the wound usually pushes the tube out of the peritoneal cavity. A majority of the procedures were performed in less than five minutes. No surgical difficulties were encountered, and no immediate complications or complaints were reported. Patients were usually hospitalized for one or two nights. Early postoperative complications or complaints were reported for 8.4% of the not-recently-pregnant patients and for 4.1% of the postpartum patients at the 7-to-21-day follow-up visit. The most frequently reported complications and complaints were fever and lower abdominal pain. Further studies to determine the effectiveness of this type of sterilization and whether the procedure can be performed safely with local anesthetics and on an outpatient basis are being planned.

Adult↗