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Biomedical subjects

A J Rao

Publications and source records attributed to A J Rao.

At least 19 recordsLinked to original sources
PubMed1992

Chronic suppression of testicular function by constant infusion of gonadotropin-releasing hormone agonist and testosterone supplementation in the bonnet monkey (Macaca radiata).

OBJECTIVE: To study the efficacy of long-term buserelin acetate infusion to desensitize pituitary and block testicular function in adult male monkeys (Macaca radiata). ANIMALS: Proven fertile male monkeys exhibiting normal testicular function. PROTOCOL: Each of the control (n = 5) and experimental monkeys (n = 10) received a fresh miniosmotic pump every 21 days, whereas pumps in controls delivered vehicle of experimentals released 50 micrograms buserelin acetate every 24 hours. On day 170 (renewed every 60 days) a silastic capsule containing crystalline testosterone (T) was implanted in the experimental monkeys. At the end of 3 years, treatment was stopped, and recovery of testicular function and fertility monitored. RESULTS: (1) Treatment resulted in marked reduction of nocturnal but not basal serum T; (2) the pituitary remained desensitized to buserelin acetate throughout the 3-year period; (3) animals were largely azoospermic with occasional oligospermia exhibited by two monkeys; and (4) withdrawal of treatment restored testicular function, with 70% of animals regaining fertility. CONCLUSION: Long-term infertility (but restorable) can be induced in male monkeys by constant infusion of buserelin acetate and T.

Animals↗
PubMed1992

Role of calcium in secretion of chorionic gonadotropin by first trimester human placenta.

The role of calcium in regulation of secretion of human chorionic gonadotropin (hCG) by first trimester human placental minces in vitro has been investigated. Depletion of calcium in the medium by addition of EGTA resulted in a drastic decrease in the levels of immunoreactive hCG in the medium with consequent of accumulation of hCG in the tissue. Addition of A 23187 which is a calcium ionophore resulted in a dose dose dependent increase in the hCG in the medium and this stimulatory response could not be observed in the absence of calcium. Use of lanthanum (a calcium antagonist) in place of calcium in the medium used resulted in a significant decrease in the levels of hCG in the medium. Addition of veratridine (a sodium channel activator) stimulated hCG secretion in a dose dependent manner. These results suggest that calcium is essential for normal secretion of hCG by human placenta.

Calcimycin↗
PubMed1990

Presence of dipeptidyl peptidase II, dipeptidyl peptidase IV, and prolyl endopeptidase in effusion from patients with serous otitis media.

We have measured for the first time, using specific substrates and specific fluorometric analyses, activities of three pathophysiologically important peptidases, i.e., dipeptidyl peptidase II, dipeptidyl peptidase IV, and prolyl endopeptidase in effusions from 45 patients with chronic otitis media with effusion. In 20 patients, DPP II and DPP IV were assayed simultaneously in effusions and sera. Activity of PEP was also estimated in effusions and sera from 25 patients. The mean values (+/- SD) of DPP II and DPP IV (n = 45) and PEP (n = 25) in effusion from patients with OME were 0.020 +/- 0.007, 0.66 +/- 0.04, and 0.040 +/- 0.006 nmole/min/mg protein, and 0.21 +/- 0.01, 16.2 +/- 1.87, and 1.90 +/- 0.23 nmole/min/ml of effusion, respectively. The mean values (+/- SD) for DPP II, DPP IV, and PEP in sera were 2.82 +/- 0.18, 54.8 +/- 1.23, and 3.73 +/- 0.33 nmole/min/ml of serum, respectively, which were similar to our previously reported values. Activities of DPP II, DPP IV, and PEP of serous effusions were comparable to those in serum. However, there was no significant correlation between their activities in serum and effusion. This may suggest that the major source of these enzymes in effusions may not be serum but the cells in the middle ear.

Adult↗
PubMed1990

Spectral analysis of airflow sounds in patent versus occluded tracheostomy tubes: a pilot study in tracheostomized adult patients.

Cannula occlusion is a life-threatening postoperative complication of tracheostomy. Current management largely relies on nursing care for prevention of fatalities because no proven mechanical, machine-based support monitoring exists. The objective of this paper was to address the problem of monitoring the state of cannula patency, based on analysis of airflow acoustic spectral patterns in tracheostomized adult patients in the patent and partially occluded cannula. Tracheal airflow sounds were picked up via a condenser microphone air-coupled to the skin just below the tracheal stoma. Signal output from Mic was amplified, high-pass filtered, digital tape-recorded, and analyzed on a mainframe computer. Although airflow frequencies for patient cannulae were predominantly low-pitched (0.1 to 0.3 kHz), occluded tubes had discrete high-pitched spectral peaks (1.3 to 1.6 kHz). These results suggest that frequency analysis of airflow sounds can identify a change in the status of cannula patency.

Adult↗
PubMed1989

Studies on non-specific interference due to serum in the avidin-biotin microELISA for monkey chorionic gonadotropin and a method for its elimination.

A study has been carried out on the non-specific interference due to serum in the avidin biotin microELISA for monkey chorionic gonadotropin. Results suggest that it is not due to any proteolytic activity in the serum, but immunoglobulin or associated factors interfering at the level of antigen-antibody interaction. This interference was eliminated by heating samples at 60 degrees C for 30 min.

Animals↗
PubMed1989

Model of a new generation of tracheostomy and endotracheal tubes. A preliminary study of sensors to monitor obstruction.

The feasibility of monitoring cannula obstruction was studied by conversion of the electrical resistance of substances that are capable of causing obstruction into audible auditory signals. Copper-nickel-gold electrodes were thermal pressed onto polyimide-based flexible films placed as 1-mm wide strips along the inner surface of tracheostomy and endotracheal tubes. The responses were fed into a resistance-to-frequency converter (IC 555 timer), and the output was frequency selected to generate auditory responses through a piezoelectric beeper. Quantitative estimates of responses from the IC output were computer averaged. Instantaneous obstruction detection was made possible by the immediate responsiveness of the device in the presence of obstruction.

Airway Obstruction↗
PubMed1988

Use of pulse oximetry for monitoring tracheostomy tube obstruction.

Experimental studies were performed on dogs for monitoring postoperative tracheostomy tube obstruction using a pulse oximeter. While a 25% obstruction of the cross-sectional area of the tube did not alter the oxygen saturation, obstruction of 40% and above resulted in a drop in the oxygen saturation level which corresponded to the degree of obstruction. The greater the degree of obstruction, the sooner was the fall of oxygen saturation. Therefore a pulse oximeter could be effectively put to use to monitor tracheostomy tube obstruction.

Animals↗
PubMed1987

An avidin-biotin micro-enzymeimmunoassay for monkey chorionic gonadotrophin.

The avidin-biotin micro-enzymeimmunoassay used antiserum to the beta-subunit of sheep LH, biotinylated hCG as tracer and pooled serum from pregnant monkeys as a reference preparation of monkey CG. The assay was validated for specificity, by checking serum samples known to contain high quantities of LH, and false positive results were eliminated to a great extent by prior heating of serum samples at 60 degrees C for 30 min. In 45 bonnet monkeys the test gave 10 true positives, 34 true negatives and 1 false positive, i.e. an accuracy of 97%. The serum profiles of CG, measured by the EIA, in bonnet, cynomolgus and rhesus monkeys during early pregnancy were very similar to those reported for bonnet and rhesus monkeys when a liquid-phase radioimmunoassay was used.

Animals↗
PubMed1986

Gonadotropin releasing hormone (GnRH) stimulates both secretion and synthesis of human chorionic gonadotropin (hCG) by first trimester human placental minces in vitro.

An in vitro system using the minces of placental villi from first trimester human pregnancy (6-10 weeks) has been validated to examine the effect of addition of GnRH and its analogues on hCG secreted into the medium. Addition of low concentration of GnRH or its analogues (1 X 10(-8) M to 1 X 10(-6) M) resulted in an increase in the quantity of hCG in the medium, while addition of high concentrations of GnRH resulted in an inhibitory effect. Of the analogues tested, Buserelin was highly effective in exerting an inhibitory effect. A significant increase in 35S-methionine incorporation into immunoprecipitable hCG was noticed in the presence of GnRH. These results suggests that GnRH stimulates both synthesis and secretion of hCG by first trimester human placenta.

Chorionic Gonadotropin↗
PubMed1979

Adrenocorticotropin. 52 Synthesis and biological activity of adrenocorticotropic peptides with cystine bridges.

Three analogs of the amino terminal nonadecopeptide of adrenocorticotropin which incorporate cystine cystine bridges between positions (5, 10), (3, 10), or (2, 10) have been synthesized. All of the peptide analogs showed reduced biological activity; however, the peptide with the 5, 10 cystine bridge was shown to possess significantly higher lipolytic activity in rat fat cells than the peptides with a 3, 10 or 2, 10 cystine bridge.

Adrenal Glands↗