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Biomedical subjects

S K Guha

Publications and source records attributed to S K Guha.

At least 37 records · Page 2Linked to original sources
PubMed1994

Multifactorial interactions in the aetiopathogenesis of EPH-Gestosis--a hypothesis.

The aetiopathogenesis of EPH-Gestosis or pre-eclampsia-eclampsia is still not clear. Although many hypotheses implicating environmental, nutritional, immunological, and genetic factors have been put forward, no hypothesis provides the scientific basis for the early spiral arterial degenerative changes, and incomplete physiological trophoblastic invasion of the spiral arteries, leading to a high utero-placental resistance with reduced blood flow remains unexplained. To get an insight into the basic pathogenesis of EPH-Gestosis, the following hypothesis has been proposed. The hypothesis considers an abnormal proliferation of the spiral vessels as the key factor in the pathogenesis of the high uteroplacental resistance and the endothelial dysfunctions in EPH-Gestosis. Further it is proposed that this proliferation is on account of the enhanced polymerization of the deficient DNA triggered by the high steroidal level and relatively low micronutrient level in EPH-Gestosis during the early formative stages of the placental circulation. Steroidal hormone helps in polymerization of the DNA, micronutrients exert a controlling influence through DNA synthesis on cell proliferation. A critical balance of hormone-micronutrients such as vitamin A, B12, folic acid, etc., therefore, seems necessary for normal cellular proliferation. It appears therefore that there probably exists an imbalance with a high estrogen and a relatively low micro-nutrient level in EPH-Gestosis, triggering off a process of abnormal spiral vessel proliferation. These abnormal vessels with a deranged endothelial function may prevent the second wave of normal trophoblastic invasion assumed to be important for the establishment of the low resistance uteroplacental circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Effect of moderate & high loadings on the proteoglycans & water content of bovine knee joint articular cartilage.

Variations in proteoglycans and water content of the knee joint cartilage were found to occur when the joint was subjected to articulating motion under moderate and high loadings. It was found that at a moderate load of 150 kg there were an increase in the percentage of proteoglycans but the percentage decreased when the joint was articulated at a high loading of 300 kg. It has also been observed that the ratio of water content and the proteoglycans decreased at moderate load, whereas the ratio increased at high load. The observed changes in proteoglycans and water content in extracellular matrix with moderate and high loadings suggested that articular cartilage properties respond to mechanical stresses.

Animals↗
PubMed1993

Phase I clinical trial of an injectable contraceptive for the male.

Earlier studies on the rat and the monkey had demonstrated that an injection of styrene maleic anhydride (SMA) in a solvent vehicle of dimethyl sulphoxide (DMSO) into the lumen of the vas deferens is toxicologically safe and has contraceptive action. Phase I clinical trial was therefore undertaken on 38 male volunteers giving varying doses of SMA, ranging between 5 mg and 140 mg, into each vas deferens. A dose of 70 mg is the predicted therapeutic dose based on animal data. That the compound is within the vas deferens lumen during the period of the safety assessment is inferred from the effect on the spermatozoa count in ejaculates which reach azoospermic levels in the higher dose ranges. The treatment is well tolerated with only minimal side effects in a few cases and no long-term adverse effects.

Adult↗
PubMed1992

Computer as a group teaching aid for persons who are blind.

A concept has been formulated whereby a teacher in a classroom for students who are blind can communicate line diagrams and text directly to the students. This approach is based upon a single computer placed on the teacher's desk, with monitors on the students' desks. Access to the information displayed on the monitors is obtained by means of an optoelectronic sensor and vibrotactile output. Two versions of the sensor have been made--one for sensing line diagrams, and the other for Braille text. A simple, low-cost arrangement has also been designed by which students who are blind can prepare a hard copy of the diagrams from the monitor display. The special feature of the system is that it allows the teacher to convey information directly to the students, that is, diagrams and text that have been entered into the computer while the students are in the classroom. Information previously stored on floppy disks may also be communicated in this way. This methodology will overcome the current limitation where the teacher is able to hand out only embossed diagrams and text that have been previously prepared. Learning to use the new system can be accomplished in a short time, with the added advantage that the system is relatively inexpensive.

Blindness↗
PubMed1991

Set-covering diagnostic expert system for psychiatric disorders: the third world context.

This paper presents an implementation of the set-covering model for diagnosing psychiatric disorders. Such a model is useful as the basis for the inference mechanism of an expert system in that it provides a satisfactory solution to the difficult problem of multiple simultaneous disorders. The set covers have been formed through the 'diagonal search method' in which the combination of an element with the rest of the elements along the diagonals in the combination matrix was found to be adequate. 'Abductive logic' has been used to reach the possible final solution. Another feature of this expert system is its elicitation system. Provision has been made in the expert system for observations to be made and questions to be asked of the patient in difficult-to-elicit psychiatric signs. It makes this expert system usable by the non-expert clinicians. This has been specially designed in the context of third-world conditions. The system has been tested on cases given in the DSM-III case book with 100% success. However, the system's knowledge should be expanded and refined if it is to be used in psychiatric clinical practice.

Developing Countries↗
PubMed1991

Morphological changes in the bovine articular cartilage subjected to moderate and high loadings.

This study aims at examining the morphological changes in the cartilage structure of the bovine knee joint when the amputated joints are subjected to (a) a moderate load of 150 kg and (b) a high load of 300 kg and fitted on a knee joint articulating machine at 45 cycles/min for 2 h. The scanning-microscopic study of the surface structure of the experimental and control cartilage shows no appreciable change in the surface morphology of the cartilage when subjected to the moderate load of 150 kg. However, in the case of the high load (300 kg) there is appreciable change in the fibrillary structural pattern of the surface morphology. Histologically too, no appreciable change was noticed when subjected to moderate loadings, but in the case of high loading the cartilage develops roughness of the surface with occasional small clefts.

Animals↗
PubMed1991

Shear properties of articular cartilage of a bovine knee joint subjected to moderate and high loads: an experimental study.

Freshly excised bovine knee joints were subjected to oscillation under constant load on a specially designed knee joint articulating machine with the joints subjected to moderate and high loadings of 1471.5 and 2943 N respectively. Instantaneous and equilibrium shear moduli of the articular cartilage obtained from the experimental knee joints were measured on a mechanical indentor (DuPont 943 TMA) and compared with the corresponding values of the shear moduli of the cartilage obtained from the control knee joints. At moderate load, both the instantaneous and the equilibrium shear moduli exhibit significant increase in their values. However, at high load the constant shear moduli showed a decrease in its value whereas the value of the equilibrium shear modulus was observed to increase slightly.

Animals↗
PubMed1990

Time-controlled injectable occlusion of the vas deferens.

An injectable method of obtaining vas deferens occlusion is presented. The agent used is styrene maleic anhydride (SMA) with dimethyl sulphoxide as the solvent. The special feature of the approach is that after a period of time, spermatozoa passage is spontaneously reestablished. By varying the dose of SMA administered, the interval between injection and restoration of spermatozoa flow can be regulated from as short a period as about 3 months to more than five years.

Animals↗
PubMed1989

A new stretcher design for easy manoeuvreability on narrow staircases and rough ground for developing countries.

Rough terrains with obstacles, narrow staircases and inadequate space to position the ambulance conveniently in relation to the exit door of houses, often encountered in developing countries like India, make it difficult if not impossible to carry patients using conventional stretchers. A novel two-wheeled stretcher to overcome the limitations has been designed, fabricated and tested for a decade. The special features allow even one stretcher operator to transport a patient over all types of ground, down staircases with landings so small as not to provide space for a regular stretcher to turn into and out from the ambulance. This wide range of facilities has been obtained by incorporating very simple and low-cost devices such as a metal guard over two wheels, friction belts and an ergonomically designed tie bar system. Usage in handling various medical and surgical emergency cases has proven the efficacy and acceptability of the design.

Ambulances↗
PubMed1986

The enzymic synthesis of ribose-1,5-bisphosphate: studies of its role in metabolism.

Ribose-1,5-bisphosphate is synthesized in a reaction that uses ribose-1(or 5)-P as the phosphoryl acceptor and the acyl-P of 3-phosphoglyceryl phosphate as the donor. Glucose-1,6-bisphosphate is synthesized in a similar reaction. The relative activity with the two substrates remains unchanged over almost 300-fold purification of the enzyme, indicating that glucose-1,6-bisphosphate synthase catalyzes both reactions. The relative V/Km values for alternative phosphoryl acceptors are ribose-1-P (1); glucose-1-P (0.30); mannose-1-P and ribose-5-P (0.11); glucose-6-P (0.10); 2-deoxyglucose-6-P (0.03); and 2-deoxyribose-5-P (0.02). Fructose-1- and 6-phosphates are not substrates. The synthesis of both ribose-1,5-bisphosphate and glucose-1,6-bisphosphate is inhibited by physiologically significant levels of fructose-1,6-bisphosphate, glycerate-2,3-bisphosphate, glycerate-3-phosphate, citrate, and inorganic phosphate. Ribose-1,5-bisphosphate is a strong activator of brain phosphofructokinase.

Animals↗
PubMed1986

Objective grading of the loss of pain and touch sensations in leprosy patients.

Two new instruments named Pain/Touch Sensation Testing and Grading devices, which provide standardized and graded stimuli of pain and touch, respectively, were employed to grade the sensory loss at the center of 110 lesions in 97 patients. The grades of sensory loss for pain were 0 (no sensory loss) in 8 lesions, 1 in 6 lesions, 2 in 14 lesions, 3 in 26 lesions, 4 in 19 lesions, and 5 (complete loss) in 37 lesions (total 110 lesions). Grades of sensory loss for touch were 0 in 12 lesions, 1 in 3 lesions, 2 in 5 lesions, 3 in 9 lesions, 4 in 15 lesions, and 5 in 22 lesions (total 66 lesions). Reevaluation done after 2-40 weeks in 46 of these lesions revealed that the grade for pain had decreased in 17 lesions, increased in 4, and remained the same in 25. The grade for loss of touch sensation had decreased in 10, increased in 1, and remained the same in 35. Grading of the sensory loss in most of the 1-cm-square areas of the entire lesion, done in 19 patients (26 lesions), revealed that the sensory loss was not uniform all over the lesion and it was also not maximum at the center of the lesion, though generally it was less at the margin in comparison with the central area. Follow up of 11 of these lesions revealed a decrease in the grades in 7 lesions for both pain and touch sensations, while 2 lesions showed a decrease in the grades for touch sensation only.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1985

The synthesis of mannose 1-phosphate in brain.

The interconversion of mannose-6-P and mannose-1-P in brain has been shown to be catalyzed by a distinct enzyme. The enzyme has been separated from most of the phosphoglucomutase activity of the brain. The residual phosphoglucomutase activity (less than 1%) may be associated with phosphomannomutase itself. Mannose-1,6-P2 or glucose-1,6-P2 is required for the reaction as well as a divalent cation (Mg2+ greater than Co2+ greater than Ni2+ greater than Mn2+). Glucose-1-P, glucose-6-P, and 2-deoxyglucose-6-P are also substrates or inhibitors. Other phosphorylated sugars tested, glucosamine-6-P, N-acetylglucosamine-6-P, galactose-6-P, fructose-6-P, ribose-5-P, and arabinose-5-P, do not affect the rate of the reaction when assayed in the presence of mannose-6-32P.

Animals↗
PubMed1985

Contraception in male monkeys by intra-vas deferens injection of a pH lowering polymer.

A new male method of contraception by injecting a polymer, styrene-maleic anhydride (SMA), into the lumen of the vas deferens has been studied on rhesus monkeys. The polymer has the dual feature that it can occlude the vas deferens lumen and also it can inhibit the fertilising ability of spermatozoa by virtue of the pH lowering effect. Matings with females were carried out when the lumen was completely occluded giving azoospermia as well as with partial block and spermatozoa present in the semen. All matings were infertile. Data up to one year is presented. All indications are that the contraceptive effect will last for a considerably long period.

Animals↗
PubMed1985

Minimum temperature felt as hot (MTH)--a new concept for grading the loss of temperature sensation in leprosy patients.

In order to grade the loss of the temperature sensation in the skin of leprosy patients, a newly designed instrument called the Temperature-Sensation-Testing-and-Grading device has been employed to determine the minimum temperature felt as hot (MTH) at the skin area. The MTH in normal subjects was observed to vary from one region of the body to another; it was generally higher on the distal parts of the extremities compared to the proximal parts; and it was also higher on the lower extremities compared to the upper ones. The abdomen and the back generally had the lowest values. There were no variations according to age (11-80 years) or sex and no differences on symmetrical sites of the body. The MTH value, however, showed a dependence on the environmental temperature, the values being lower at low environmental temperatures and higher at high environmental temperatures. But at the same site and the same environmental temperature, the MTH value was found to be almost constant. Different individuals had different MTH values at the same body site and even at the same environmental temperature. The unaffected skin of leprosy patients showed values comparable to the controls. At the leprosy lesions, however, the degree of sensory loss could easily be determined in comparison with the MTH at the contralateral/adjoining unaffected skin. Out of 54 leprosy patients, 7 patients had no sensory loss; in 27 patients the loss varied between 1 degree C and 20 degrees C; while in 20 patients the loss was complete--they could not perceive even 50 degrees C as hot.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Role of inosine 5'-phosphate in activating glucose-bisphosphatase.

Glucose-bisphosphate (G1c-1,6-P2) phosphatase has been purified greater than 200-fold from the cytosol of mouse brain. As reported earlier, the enzyme requires inosine monophosphate (IMP) and Mg2+ for activity [Guha, S.K., & Rose, Z. B. (1982) J. Biol. Chem. 257, 6634-6637]. Kinetic parameters and the role of IMP have been further investigated. When Glc-1,6-P2 and IMP are both varied, double-reciprocal plots of the data form a parallel line pattern. With 2 mM Mg2+, the Km obtained for G1c-1,6-P2 is 20 microM and the Ka for IMP is 9 microM. Co2+, Mn2+, and Ni2+ activate less effectively than Mg2+. The apparent Ka for Mg2+ decreases with increasing G1c-1,6-P2, and the observed Km of G1c-1,6-P2 decreases with increasing Mg2+. The extrapolated value of the Ka of Mg2+ at infinite substrate is 86 microM. Mg2+ does not affect the Ka of IMP. The phosphatase activity is optimal at pH 7. The phosphatase is not completely specific since mannose 1,6-bisphosphate is hydrolyzed and guanosine monophosphate activates. However, fructose 1,6-bisphosphate is no more than a poor inhibitor, and adenine nucleotides are neither activators nor inhibitors. The products of the reaction are glucose-1-P and glucose-6-P, in a ratio of 2:3, and Pi. Both glucose-P's are competitive inhibitors with respect to IMP [Ki(glucose-1-P) = 5 microM; Ki(glucose-6-P) = 18 microM]. Neither glucose-P competes with G1c-1,6-P2. The demonstration of an exchange reaction between G1c-1,6-P2 and glucose-6-P is evidence for the phosphorylation of the enzyme by the substrate. The exchange reaction requires Mg2+ and is inhibited by IMP. The observation of the exchange reaction and its elimination by IMP indicates that the low level of phosphoglucomutase activity that remains with the phosphatase throughout purification is an inherent property of the phosphatase. The requirement of glucose-bisphosphatase for the nucleotide IMP is consistent with possible roles for both G1c-1,6-P2 and IMP in the control of the ATP level in the brain.

Animals↗