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Biomedical subjects

R Srinivasan

Publications and source records attributed to R Srinivasan.

At least 235 records · Page 13Linked to original sources
PubMed1976

On the conformation of the disulphide group in L-cystine and its derivatives.

The terminal groups in cystine are asymmetric and hence the dissulphide group with right and left chirality may not have equal energy. An attempt is made to resolve this problem through energy calculation using semi-empirical methods involving non-bonded and electrostatic interactions and simple Pauling type torsional potential for the disulphide group. The results are discussed in the light of experimental data.

Cystine↗
PubMed1975

The development of the granular convoluted duct in the rat submandibular gland.

The development of the granular convoluted duct in the submandibular gland of male rats, 4 to 12 weeks of age, was investigated. During this period, the average weight of the gland increased from 213 to 526 mg, the total DNA and RNA contents doubled, and the protein content tripled. Radioautographs were prepared from Epon embedded sections of the gland of the rats given 3-H-thymidine and stained with toluidine blue. The glands of 4-week-old rats consisted mainly of acinar cells (45%), intercalated ductal cells (20%) and striated ductal cells (16%). A few granular convoluted ductal cells were seen in the striated duct close to the intercalated duct. The frequency (and absolute number) of granular convoluted ductal cells increased linearly from 1% (3 X 10-6) at four weeks to 26% (68 X 10-6) at eight weeks, while the calculated number of striated ductal cells remained stationary. The absolute number of acinar cells and intercalated ductal cells nearly doubled between four to eight weeks of age. The proliferative activity of all cell types declined with age but between six and ten weeks of age the rate of proliferation of ductal cells was relatively higher than the rate of proliferation of the acinar cells. Morphologically the size and number of granules in the granular convoluted ductal cells increased with age. Based on the above data it is concluded that the granular convoluted ductal cells developed from that segment of the striated ductal cells which is in close proximity with the intercalated ductal cells. The heterogeneity of the granules in the granular convoluted ductal cells observed from six weeks of age might denote the functional diversity of the cells.

Age Factors↗
PubMed1975

Cardiac evaluation of a physical rehabilitation program for patients with ischemic heart disease.

A reconditioning exercise program that was applied to group of 12 coronary patients resulted in an increase of their tolerance to physical work and of their maximal working capacity. In some instances the improvement in physical condition was accompanied by changes in indicators of cardiac function which suggest that an improvement in myocardial performance also occurred. Although some evidence of this has been presented, more studies are needed for substantiation. It is believed, on the other hand, that to explain the improvement of the patient, it is not necessary to invoke an improvement of myocardial performance. An improvement of patient's tolerance to physical work may also be explained by extracardiac mechanisms that produce changes in arterial peripheral resistance, regional blood flow distribution, overall mechanical efficiency, muscle capillarization, fiber size and mitochondrial enzymatic activity, patterns of sweating, adaptation between pulmonary ventilation and circulation, work of breathing efficiency, autonomic nervous system balance and in the adaptive responses of the neuroendocrine system which mediate between psychic and physiological behavior. All of these changes have been observed in healthy individuals submitted to physical training. It is plausible to assume that they may also occur in the patient with ischemic heart disease. What is to be shown is which one or which ones of these mechanisms prevail in a given individual.

Adult↗
PubMed1972

Modeling the carotid sinus baroreceptor.

A mathematical model that describes the relationship between sinus pressure and nerve discharge frequency of the carotid sinus baroreceptor is presented. It is partly based upon the single-fiber data obtained by Clarke from the sinus nerve of a dog. The model takes into account what is currently known about the physiology of the baroreceptor. It consists of two nonlinear ordinary differential equations and eight free parameters. With one set of values for these eight parameters, the model reproduces well the experimental results reported by Clarke for positive ramp pressure inputs. Only three parameters needed to be adjusted in order to fit the dynamic data. The remaining five were obtained from static and steady-state data.

Carotid Sinus↗
PubMedDate not supplied

A double-blind trial of high versus conventional dosages of gold salts for rheumatoid arthritis.

In a double-blind study, patients were randomly selected for treatment using conventional doses (CD; 50 mg) or high doses (HD; 150 mg) of sodium aurothiomalate given weekly by injection. Twenty-three patients were assigned to the CD group and 24 to the HD group. Neither efficacy nor toxicity correlated with serum gold concentrations. Conventional doses were as efficacious as high doses with respect to both rapidity and degree of response. However, side effects were much more frequent and severe in the HD group. Thus there is no reason to recommend a 150 mg weekly dosage regimen.

Adult↗
PubMedDate not supplied

Proton-decoupled 31P chemical shift imaging of the human brain in normal volunteers.

Proton-decoupled, 31P three-dimensional (3-D) chemical shift imaging (CSI) spectra have been acquired from the entire human brain using a new dual tuned resonator. The resonator operates in quadrature mode to provide improved sensitivity, excellent B1 homogeneity and reduced power deposition at both frequencies. Proton-decoupled and fully NOE enhanced, 31P spectra were acquired from normal volunteers using Waltz-4 proton decoupling with continuous wave bi-level excitation applied through a second radio frequency channel. Well resolved peaks in the phosphomonoester (PME) and phosphodiester regions were obtained from nonlocalized FIDs and spectra localized with 3-D CSI without processing for resolution enhancement. pH measurements made over large regions of the brain using the P(i) resonance show no significant variations (6.9 +/- 0.02) for a single individual. The improved spectral resolution and sensitivity of the PME resonances results in more well defined metabolite images of the PME peak region.

Brain↗
PubMedDate not supplied

Observation on the host parasitoid interaction between Periplaneta americana, the American cockroach and Tetrastichus hagenowii, an oothecal parasitoid.

Investigations were carried out on the host parasitoid interaction between Periplaneta americana, the American cockroach and Tetrastichus hagenowii, an oothecal parasitoid. This gregarious female parasitoid infected and or oviposited in only one host and caused 100% mortality of the infected host. However, increase in parasitoid density decreased the progeny production and influenced the sex ratio. The progenies produced were male biased. When host preference was tested by offering oothecae of different species of cockroaches. T. hagenowii showed a predilection towards the oothecae of P. americana, suggesting its host specificity.

Animals↗
PubMedDate not supplied

Signet-ring cell variant of large cell lymphoma.

A diffuse, large cell lymphoma of palatine tonsil was found to contain a considerable number of enlarged tumor cells with prominent, hyaline, Russell body-type cytoplasmic inclusions displacing the nucleus peripherally and, thus, the morphologic features of signet-ring cell lymphoma. Immunoperoxidase staining revealed that the contents of the signet-ring cells were strongly positive for mu heavy chains and kappa light chains. Ultrastructurally, Russell body-type inclusions consisted of multiple, angulated, electron-dense crystalloids enclosed within expanded segments of rough endoplasmic reticulum.

Humans↗