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Biomedical subjects

N Parekh

Publications and source records attributed to N Parekh.

65 records · Page 4Linked to original sources
PubMed1976

Renal test dyes III. Effect of dyes suitable for renal passage time measurements on renal function.

The effects of the triaryl-methane dyes Lissamine Green SF (LF SF). Lissamine Green BN (LG BN), Lissamine Green V (LG V) and Kiton Pure Blue V (KPB V) on renal functions of rats and on sodium transport across isolated frog skin have been investigated. The experiments failed to show any natriuretic or diuretic effects of the purified dyes on the rat kidney. In the continuous infusion experiments, which lasted 3 1/2 h, the amount of the dye infused was equivalent to a passage time measurement every 3 min. In rapid injection experiments LG V was injected every 5 min for 1 h. The dyes did not have any effect on insulin clearance either. Previously reported effects of the dyes can be partly explained by the presence of sodium sulfate in commercially available dyes. Experiments with LG V showed that the dye also has no effect on the potential difference or short circuit current across the isolated frog skin. This supports their usefulness as renal test dyes.

Animals↗
PubMed1976

Renal test dyes IV. Intravital Fluorescence microscopy and microphotometry of the tubularly secreted dye sulfonefluorescein.

The present study describes for the first time the use of the fluorescent dye sulfonefluorescein for intravital microscopy and microphotometry on the renal surface of rats. With help of this dye tubular secretion can be observed in mammalian kidney in vivo. Tubular secretion can further be quantified with microphotometrical measurements. The molecular structure of sulfonefluorescein is closely related to phenol red, which is known for its tubular secretion. Clearance experiments also show a secretion of sulfonefluorescein. The secretion can be inhibited by probenecid. Ureter ligation causes a strong increase in tubular concentration of the dye. After a temporary ischemia dye accumulation in tubular lumen is greatly reduced.

Animals↗
PubMed1976

Intravital microscopical studies of the tubular urine flow in the conscious rat.

A method was developed which allowed microscopical observation of the kidney in conscious and anesthetized rats. The left kidney was freed from surrounding tissue and placed in a plexiglas chamber with a protecting window which was sewed into the skin of left flank. During the experiments the covering glass was removed. Tubular transit time was measured in the conscious state and during inactin anesthesia in control rats as well as in unilaterally nephrectomized rats with compensatory hypertrophy. Transit time of lissamine green within proximal convolutions and Henle's loop increased significantly in both series during anesthesia. Luminal and outer diameters of proximal tubules in control rats were evaluated from microphotogramms of the kidney surface, they did not change due to anesthesia. The results could be mainly explained by a decrease in glomerular filtration rate due to anesthesia. Possible mechanisms are discussed which could explain the observed transit time in Henle's loops and distal convolutions in control and uninephrectomized rats.

Anesthetics↗
PubMed1976

Percutaneous transfemoral embolization of arterio-infundibular-venous fistula.

An arterio-infundibular-venous fistula complicating partial nephrectomy was embolized successfully via transfemoral catheterization of the right renal artery using autologous muscle. The use of autologous material occluded this vascular malformation with preservation of renal function in the remaining portion of the kidney. The technique was lifesaving since this patient was in critical condition and could not tolerate an operation.

Adult↗
PubMedDate not supplied

Insulin-like growth factor-I receptor antagonism results in increased cytotoxicity of breast cancer cells to doxorubicin and taxol.

Therapeutic strategies for patients with advanced-stage adenocarcinoma of the breast frequently include the use of cytotoxic chemotherapy. Insulin-like growth factor I (IGF-I) receptor, a key factor in cell-cycle regulation, is frequently overexpressed in high-grade breast cancers. IGF-I receptor overexpression in these tumors may provide a target for novel molecular therapy against this disease. Early passage samples of estrogen-responsive (ER+) MCF 7 and estrogen receptor-negative (ER-) MDA-231 cells were cultured in semi-confluent conditions. Dose-titrations were performed for doxorubicin and taxol with receptor modulation using IGF-I or a competitive receptor inhibitor, alphaIR3. The addition of 100 ng/ml IGF-I resulted in a >2-fold mitogenic response in both ER+ and ER- cells. Receptor activation prior to the treatment with cytotoxic chemotherapeutic agents altered the pattern of response with a 26.3% increase in IC50. Doxorubicin and taxol both produced dose-related toxicity with IC50 of 0.05 microg/ml and 0.00 microg/ml respectively. The addition of alphaIR3 resulted in increased cytotoxicity in IGF-I stimulated cells compared with the use of doxorubicin or taxol alone. These results suggest that IGF-I receptor modulation alters the response to cytotoxic chemotherapeutic agents in breast cancer cells.

Antibodies, Monoclonal↗