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Biomedical subjects

T Khan

Publications and source records attributed to T Khan.

At least 73 records · Page 4Linked to original sources
PubMed1989

A study of breastfeeding and the return of menses and pregnancy in Karachi, Pakistan.

A longitudinal study of breastfeeding women was conducted to determine whether breastfeeding frequency is associated with the length of postpartum amenorrhea. The data are also conducive to testing the guidelines of the "Bellagio Consensus" (i.e., that there is no more than a 2% chance of pregnancy during breastfeeding in the first six months postpartum in the absence of vaginal bleeding and regular supplements). Twenty-eight breastfeeding women were followed-up weekly in Karachi, Pakistan. The frequency of breastfeeding was found to be a poor correlate of the duration of amenorrhea. Thirty-six percent of the women became pregnant during the study. However, all were having menses and/or giving regular supplements before the estimated date of conception, consistent with the Bellagio Consensus. In countries such as Pakistan, where contraceptive use is low, active promotion is needed to prevent the further decline of breastfeeding in order to retain its contraceptive as well as other maternal and child health benefits.

Adult↗
PubMed1989

Urethral responses to sacral stimulation in chronic spinal dog.

Urethral activity was investigated in the awake chronic spinal-injured canine using urodynamic recordings, video cystofluoroscopy, and urethral pressure recordings without anesthesia. Bladder contractions and voiding were induced by electrical stimulation with epidural electrodes inserted into the sacral canal. Urethral pressure remained elevated during stimulation and for 1-3 s afterward. Poststimulation voiding occurred with three different patterns: 1) pulsatile voiding in which squirting of urine was associated with contractions in the membranous urethra; 2) "on and off" voiding in which pulsatile flow was interrupted for brief periods of time; and 3) steady-stream voiding in which nonpulsatile flow was followed by pulsatile flow. Viewing these voiding patterns with fluoroscopy indicated that the proximal membranous urethra was important in all of the patterns. We conclude that in the chronic spinal-injured canine the skeletal muscle within the membranous urethra (rhabdosphincter) is involved in responses to sacral stimulation and various voiding patterns.

Animals↗
PubMed1989

Sacral epidural electrodes for voiding in the chronic spinal dog.

Recent reports have shown that electrical stimulation of the bladder wall or sacral nerves is effective for bladder management in the spinal cord injured (SCI) patient. However, less invasive methods are needed for electrode implantation. A modified percutaneous procedure for implanting needle electrodes in the sacral canal was evaluated. Stimulation with these electrodes were effective for inducing voiding with little residual volume after the recovery of bladder reflexes, 3 weeks after experimental spinal cord injury in the dog. An optimum electrode arrangement involved a single midline monopolar electrode located between sacral foramina L7 and S1. However, at low stimulating current, lateral electrodes adjacent to sacral nerves were more effective than midline electrodes for inducing voiding. Stimulation parameters that were effective for daily voiding were 10 pps, 1.5-5 mA, 0.3 ms pulse duration, and 2- to 3-second stimulation periods.

Animals↗
PubMed1987

Effect of injury on nerve growth factor uptake by sensory ganglia.

The level of the nerve growth factor protein, NGF, in vivo has a profound influence on axonal sprouting by sensory neurons of vertebrate dorsal root ganglia. There is evidence also that NGF may play similar roles in cholinergic central structures in brain. In both instances, retrograde transport of NGF has been demonstrated. Here we examined uptake of NGF by DRG neurons in response to contusion injury of the spinal cord. Under these conditions there was uptake and transport of NGF into large DRG neurons via central processes but no uptake by non-DRG central neurons. Thus, any effects of NGF on spinal neurons or their processes would be secondary to the direct effects of NGF on DRG neurons.

Animals↗
PubMed1987

Increased axonal transport in peripheral nerves of thiamine-deficient rats.

Thiamine deficiency has been implicated as a significant contributing factor in the development of peripheral neuropathies in chronic alcoholic patients. We hypothesized that thiamine deficiency may lead to an alteration in axonal transport because it has been associated with "dying-back" neuropathies and its importance in neural tissue has been demonstrated with antimetabolites. To test this possibility rats were made thiamine-deficient by feeding a liquid diet lacking thiamine. Control rats were pair-fed a complete liquid diet. The deficiency developed after 3 to 4 weeks and was evidenced by anorexia, weight-loss, and a significant increase in the erythrocyte transketolase activity ratio. Also, the sural nerve conduction velocity was found to be significantly reduced in these animals (18.74 m/s) relative to that of pair-fed control rats (31.99 m/s). In vitro transport experiments utilizing dorsal root ganglia-sciatic nerve preparations indicated that twice as much [35S]methionine-labeled protein accumulated at a ligation by fast transport in the thiamine-deficient rats as in nerves of their pair-fed controls. There was no difference in the level of incorporation of radioactive precursor into the dorsal root ganglia. The increase in transport suggests that thiamine deficiency per se has no detrimental effects on the transport machinery and process, but may indicate extensive regenerative activity in the distal portions of these axons.

Animals↗
PubMed1985

Ultrastructural changes in rat aortic endothelium during contrast media infusion.

A rat model was employed to investigate contrast media (CM) induced ultrastructural changes in the vascular endothelium. Ionic contrast materials such as Renografin-76 (diatrizoate meglumine diatrizoate sodium), MD-76 (diatrizoate meglumine diatrizoate sodium), and Angiovist (meglumine diatrizoate) were injected into the femoral vein of anesthetized male Wistar rats (240-260 g) and allowed to circulate. Control animals were similarly injected with equiosmolar sucrose and physiologic saline. The thorax was opened 15 minutes, 1 hour, and 4 hours postinjection and cardiac perfusion performed using Karnovsky's fixative; the thoracic aorta was then surgically removed, and processed for transmission electron microscopy. All CM produced shrinkage in cell cytoplasm and nuclear structures thereby causing distortions in cell morphology. In control tissues, however, no such ultrastructural damages were noted. Within 15 minutes of CM infusion, electron dense granules were seen on the luminal surface of endothelial cells, in pinocytotic vesicles, as well as in the gap junctions between cells. These observations indicate that contrast media intake occurs via vesicular transport, and through the cell junction.

Animals↗
PubMed1985

Immunoglobulin E in psoriasis evaluated by paper radioimmunosorbent and paper enzyme-immunosorbent tests.

Serum IgE concentrations were determined by the paper radioimmunosorbent test in 56 patients with psoriasis and 50 normal controls, and by the paper enzyme-immunosorbent test in 32 of these patients and 50 controls. Elevated IgE levels were found in 26 (46%) of 56 patients with psoriasis and in 1 normal control (2%). The mean value (208 U/ml) in 56 patients was significantly higher than in normal controls (31 U/ml). Thirteen of 19 patients (68%) with extensive involvement (greater than 20% body surface) had an increased IgE level; the mean value (365 U/ml) was 4 times greater than in 17 patients with limited lesions (89 U/ml) and 12 times higher than in 50 normal controls (31 U/ml). No correlation was found between serum IgE levels and the presence of psoriatic arthritis. Both paper radioimmunosorbent and paper enzyme-immunosorbent testing produced similar results.

Adolescent↗
PubMed1983

Internal mammary implantation: the need for revival of a simple technique.

Available statistics on breast cancer indicate a high frequency of positive internal mammary nodes, which is associated with decreased five-year survival rates. The close proximity of the majority of internal mammary nodes (87 percent within 1 cm) to the internal mammary vessels makes them easily accessible to high-dose intravascular continuous irradiation by afterloading radioactive ribbons (iridium 192) in the internal mammary vessels that are surgically exposed. This is a simple technique that can be carried out at the time of mastectomy or as a separate procedure, either as a primary radiation modality, for post-XRT recurrence, or as a boost in combination with conventional parasternal radiation therapy. The step-by-step technique, indications, need for revival, and future implications are presented.

Brachytherapy↗
PubMed1982

Estrogen and progesterone receptors in breast cancer in Black Americans: Correlation of receptor data with tumor differentiation.

It has been observed that 60-70% of breast cancer patients have estrogen receptors (ER) and that nearly two-thirds of such patients respond favorably to endocrine therapy. Cytosolic ER and progesterone receptors (PgR) have been evaluated in the current study, among 146 black women with breast cancer in order to determine whether the distribution of ER and PgR differs from the national norm. The results showed following trends that were similar to reports from other institutions: (1) postmenopausal patients and primary tumors showed higher ER positivity than premenopausal patients and metastatic sites, respectively; (2) a significant correlation between the ER positivity and tumor grade; and (3) a higher PgR positivity in ER-positive patients than in ER-negative patients. However, statistically significant differences were observed in three parameters when compared to reports from other institutions on white patients: (1) a low incidence of ER-positive (46%) and high incidence of ER-negative (42%) tumors; (2) a higher incidence of poorly differentiated (55.5%) and a lower incidence of well differentiated (5.5%) tumors; tumor grade was independent of age, menopausal status, histopathology and stage; and (3) a higher percentage of patients discovered at a more advanced stage of the disease. The clinical implications of these results in explaining the relatively poorer survival of black women with breast cancer compared to whites is discussed. Whether this high incidence of PD tumors and thus a high incidence of ER negativity is due to ethnic differences and/or environmental and other factors remains to be elucidated.

Black People↗
PubMed1982

Tumors of extramammary breast tissue.

Polymastia is described and tumor formation in this condition is discussed. Two cases of carcinoma is aberrant breast tissue and one of fibroadenoma in a supernumerary breast are reported.

Adenofibroma↗
PubMed1980

Follicular carcinoma of the thyroid with metastasis to the breast.

A 75-year-old woman with two previous neck operations for follicular carcinoma of the thyroid presented with a breast mass nine years after diagnosis. The mass recurred one month after excisional biopsy. Pathological examination revealed metastatic follicular carcinoma. The breast tumor was weakly positive for estrogen receptor and positive for progesterone receptor. Recurrences in the neck and breast were resected. Residual disease in the neck and metastasis to the lungs were resolved by (131)I ablative therapy. Previous reports of thyroid metastasis to the breast were described as papillary carcinoma. This report describes a rare site of metastasis and briefly reviews the pathology, diagnosis, and management of thyroid carcinoma.

Adenocarcinoma↗