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Biomedical subjects

R Chanda

Publications and source records attributed to R Chanda.

17 recordsLinked to original sources
PubMed1999

Effect of thymectomy on serum gonadotrophins and testosterone concentration.

There is controversy about the relationship between thymic secretion and secretion of gonadotrophins and testosterone. One group of scientists reported that thymus is stimulatory to gonadotrophins and testosterone secretion, and according to other group thymic secretion is inhibitory to gonadotrophins and testosterone secretion. So we tried to observe what exactly happens to serum gonadotrophins and testosterone level following thymectomy. Thymectomy was performed in prepubertal animals and after 45 days of their operation serum gonadotrophins were measured by ELISA technique and serum testosterone was measured by RIA technique. The present study reveals a significant fall in serum FSH level along with significant rise in serum LH and testosterone level in male albino rats following thymectomy in comparison to that of sham thymectomized rats. It appears that thymus has an inhibitory influence on LH secreting gonadotrophs which has been withdrawn following thymectomy and as a result there occurs an increase in serum LH level. This LH stimulates interstitial cells of leydig and cause thereby an increase in serum testosterone level. The result also gives an indication that among the gonadotrophs in pituitary, one type is concerned with the secretion of LH while some gonadotrophs are concerned with secretion of FSH only; and the thymus possibly maintains the FSH secreting gonadotrophs intact at least till the age of puberty. Thymectomy may cause some disorganization of FSH secreting gonadotrophs which results in the fall in serum FSH level in thymectomized animals in comparison to that of sham thymectomized animal group.

Animals↗
PubMed1996

Environmental Change in the Mid-Boteti Area of North-Central Botswana: Biophysical Processes.and Human Perceptions

Increased interest in environmental change issues has led researchers to consider more integrated approaches to change dynamics. This paper examines change in terms of land degradation in north-central Botswana from both biophysical and human perspectives. Although seasonal and periodic droughts were prevalent, analysis of rainfall data over the past 70 years revealed no downward trend. However, indicators of declining productivity such as soil erosion, loss of vegetation cover, and a declining groundwater table were amply evident. The GIS analysis of remotely sensed data has shown that complete vegetation recovery after drought is not taking place, particularly in the south-central part of the study area. These areas contained the highest human and livestock population densities. The local people acknowledged facing increasing resource depletion and indicated drought as the main cause. Pressures on available resources, particularly during drought periods, appeared to have impeded the regenerative capacity of the natural vegetation cover, thereby inducing land degradation. This situation may not easily be rectified because of widespread poverty and inappropriate local perceptions of the solutions. Both of these hinder the adoption of sustainable land management.

Journal Article↗
PubMed1995

Diamine-oxidase activity and tissue di- and poly-amine contents of human ovarian, cervical and endometrial carcinoma.

In view of the conflicting reports regarding the association of di- and poly-amines along with diamine oxidase (DAO) activity in human carcinomatous growths, the present study was undertaken to establish their interrelation and to justify whether analysis of di- and poly-amine contents along with DAO may have any diagnostic value in the assessment of the carcinomatous state. It was found that diamines like histamine, putrescine and cadaverine, and polyamines like spermine and spermidine, and also DAO, increased unequivocally in human ovarian, cervical and endometrial carcinoma in comparison with their adjoining normal tissues. A reasonable explanation has been put forward to support the observations made.

Adult↗
PubMed1988

Polyamines in relation to human breast, rectal and squamous cell carcinoma.

An intimate relation between polyamines and cellular growth is evident from the existing literature; but the role of polyamines in carcinomatous growth has not been established and it remains a controversy whether polyamine analysis can be of any use as a marker for carcinoma. In an attempt to find out the relation of polyamine to carcinomatous tissues, it has been found that putrescine, cadaverine, spermine and spermidine concentrations in breast, rectal and squamous cell carcinomatous tissues, analysed under the present experiment, increased unequivocally. The result has been discussed and a reasonable explanation has been given to support the finding.

Adult↗
PubMed1987

Diamineoxidase activity and tissue histamine content of human skin, breast and rectal carcinoma.

In view of the controversy that exists regarding the histamine content and diamine oxidase activity in relation to human carcinomatous growths, the present investigation was undertaken and carcinomatous tissues of skin, breast and rectum were analysed. The result of the experiment gives a clear evidence that both histamine concentration and diamine-oxidase activity increase significantly in all the three types of growth. The result has been discussed and a reasonable explanation has been offered for the observations made.

Adult↗
PubMed1982

The sequence of 3'-termini of mRNAs from early region III of adenovirus 2.

The cloned cDNA sequences corresponding to early region III transcripts (76.6-86.0 map units) of adenovirus 2 were analyzed with a view to determine the structure of their 3'-termini. The clones pE7, pE22 and pE34, which contain a part of or the entire coding sequence for the Mr 19000 glycoprotein, showed microheterogeneity with respect to the poly(A) addition site, with the polyadenylation occurring 17, 26, or 29 nucleotides downstream from the hexanucleotide, 5'-ATTAAA-3'. The clone pE17 which represents a copy of the mRNA ending at 86.0 map units showed the presence of the sequence 5'-AATAAA-3', 16 nucleotides before the poly(A) tail.

Adenoviruses, Human↗
PubMed1975

Purkinje cell dendritic alterations after transient developmental injury of theexternal granular layer.

To examine the influence of granule cell axons on morphogenesis of their major synaptic target, the Purkinje cell dendrites, a transient injury of the external granular layer of developing rat cerebellum was induced by injecting 10 mg/kg methylazoxymethanol acetate on postnatal days 1, 2, 3 and 4. The antiproliferative action of the drug resulted in a diminution of the mitotic population which slowed the expansion of the internal granular and molecular layers. This was followed by a reconstitution of a thicker than normal external granular layer and a late phase of extensive growth. Perturbations of Purkinje cell dendritic morphology induced by this altered timing of granule cell accumulation were studied with Golgi-Cox impregnation techniques. Systematic observation were made of a number of defined abnormalities of Purkinje cells which included somas positioned below the normal monolayer; elongated dendrites; multiple somatic dendrites; S-shaped dendrites; dendrites disoriented away from the radial direction; and portions of dendrites below the soma of origin. The results indicated that most of these 'abnormalities' occur to a small extent in normal cerebellum but that these experimental conditions induced a bias in favor of their appearance. Some dendritic abnormalities, i.e., dendrites tilted out of the sagittal plane, dendrites directed toward the white matter, and apical dendrites growing vertically between cells of the external granular layer, were not noted in normal cerebellum and we attribute these particular changes to unique developmental possibilities occuring only after a more or less severe injury. This analysis of bias in dendritic morphology subsequent to subtle developmental injury provides informat on on processes of normal development and on the genesis of phylogenetic variants of Purkinje cell morphology.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

DNA synthetic ability in cerebella from temperature and handling stressed neonatal rats.

DNA synthetic ability of neonatal rat cerebellum was studied in two stressful conditions (cooling and excessive handling) which may be inadvertently imposed during the course of certain experiments. A rate study of the ability of animals handled excessively for 10 min to incorporate 14C-thymidine into the DNA tissue fraction (DNAF) from the acid soluble tissue fraction (ASF) of the cerebellum revealed a decreased DNA synthetic ability which lasted for 1 hr. Animals with very low core temperatures incorporated little 14C into the DNAF from the ASF 2 hr after an IP injection of 14C-thymidine. There was a proportional decrease in the ability to synthesize DNA as core temperature decreased.

Animal Husbandry↗
PubMedDate not supplied

Quantification of cell death in developing cerebellum by a 14C tracer method.

To study the question of whether or not cell death contributes significantly to normal or stressed postnatal brain development in a way which is biochemically quantifiable, we carried out an experiment to assess the amount of cell death in developing cerebellum. By measuring the loss of DNA content and the loss of 14C from labelled thymidine previously incorporated into the DNA fraction (DNAF) in X-irradiated neonatal animals, shown by histological methods to have cell death to the degree of degranulating the external granular layer (EGL), we showed that when cells die both label and DNA content are greatly decreased in the cerebellum. Experiments on both normal and malnourished animals showed that cell death does not contribute significantly to cerebellar development in either malnutrition-stressed or normal animals. Here, we present a biochemical tool for assessing cell death and evidence that cell death does not contribute significantly to cerebellar development.

Animals↗