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Biomedical subjects

S Aggarwal

Publications and source records attributed to S Aggarwal.

At least 109 records · Page 6Linked to original sources
PubMed1993

Studies on regulation of the ascorbic acid transporter in a cell line derived from rabbit non-pigmented ciliary epithelium.

A cell line was derived from rabbit non-pigmented ciliary epithelium. The non-pigmented ciliary epithelium is one of the two cell layers which secrete aqueous humor into the eye and concentrate ascorbic acid in the newly-formed fluid. The cultured non-pigmented epithelial cells accumulated ascorbic acid at a rate of 3-5 pmol/micrograms protein per h. As in freshly-isolated native tissue, the ascorbate uptake mechanism was sodium-dependent and could be inhibited by phloretin (apparent Ki = 2-10(-5) M). Phorbol 12,13-dibutyrate (PDBu), a protein kinase C activator, reduced the ascorbate uptake rate. The PDBu effect was concentration-dependent; at a concentration of 10(-6) M, PDBu reduced the ascorbate uptake rate to 65% of the control value. PDBu reduced the maximal rate of ascorbate uptake (determined at 200-500 microM external ascorbate) but caused no detectable change in the Km for ascorbic acid (approx. 80 microM). The PDBu-induced inhibition of ascorbate uptake persisted in the presence of ouabain and in low sodium (25 mM Na) medium, suggesting that the effect is not secondary to a change in the sodium gradient. Furthermore, no detectable elevation of cell sodium content was seen in cells equilibrated with 22Na prior to PDBu treatment. The PDBu-induced inhibition of ascorbate uptake was apparently mediated by protein kinase C because the effect was not observed in the presence of staurosporine (10(-6) M), a protein kinase C inhibitor, or in cells in which protein kinase C was downregulated. These observations suggest that activation of protein kinase C causes inhibition of the ascorbate transporter in this cultured cell line.

Alkaloids↗
PubMed1993

Asymptomatic postendarterectomy dissection of the internal carotid artery detected incidentally on MRI.

A patient who had recently undergone carotid endarterectomy was found to have internal carotid artery dissection on an MRI examination. This is a supposedly rare complication of this frequently performed operation. Since most patients with dissection of the ICA (from whatever cause) are symptomatic when the diagnosis is made, its incidental detection in an asymptomatic patient suggests that this complication may be commoner than generally recognised. We review the ways in which carotid dissection may occur during endarterectomy and the differential diagnosis of the MRI appearances.

Aged↗
PubMed1993

Postreperfusion syndrome: hypotension after reperfusion of the transplanted liver.

Sixty-nine patients undergoing liver transplantation were evaluated to elucidate the relationship between hypotension and physiological changes seen on reperfusion of the grafted liver. Measured variables included hemodynamic profiles, core temperature, serum potassium, ionized calcium levels, arterial blood-gas tensions, and acid-base state. Measurements were taken 60 minutes after skin incision (baseline), 5 minutes before reperfusion, and 30 seconds and 5 minutes after reperfusion. On the basis of changes in mean arterial pressure (MAP) patients were divided in two groups. Group 1 (n = 49) maintained MAP greater than 70% and group 2 (n = 20) had MAP less than 70% of the baseline value for at least 1 minute within 5 minutes after reperfusion. On reperfusion, changes common to both groups were 27% increase in cardiac filling pressures, 23% base deficit, and 30% serum potassium level and a decrease of 16% in cardiac output and 9% in temperature. Compared with group 1, group 2 had greater decrease in systemic vascular resistance (SVR) (1097 +/- 868 and 741 +/- 399 dyn.s-1. cm-5, respectively, P < .05) and higher potassium level (4.5 +/- 0.8 and 5.3 +/- 0.8 mmol/L, P < .05). Collectively in both groups, there was no correlation between MAP and physiological variables; however, there was a poor correlation with SVR (r = .32, P < .01). Reperfusion hypotension seen in group 2 patients correlated only with a decrease in systemic vascular resistance (r = .5, P < .05). Acute hyperkalemia, hypothermia, and acidosis do not appear to be major causes of reperfusion hypotension.

Adult↗
PubMed1993

Diagnosis of diabetic gastroparesis on Tc-99m hepatobiliary scintigraphy.

Diabetic gastroparesis is a common problem in diabetics, especially insulin-dependent diabetics. The diagnosis usually is suggested on plain radiographs and confirmed on either upper gastrointestinal barium series or radionuclide gastric emptying studies. The clinical diagnosis is not always easy and some patients may present atypically with right upper quadrant pain simulating acute cholecystitis. In these patients, hepatobiliary scintigraphy may be the initial investigation performed and may first demonstrate unsuspected gastroparesis. Therefore, it is useful for the nuclear medicine physician to be aware of this entity to ensure early diagnosis and prompt treatment. The authors report one such case of diabetic gastroparesis that was diagnosed initially on a Tc-99m hepatobiliary scan.

Adult↗
PubMed1993

A characterization of the fluorescent properties of circulating human eosinophils.

This paper presents a characterization of the fluorescence properties of human eosinophils isolated from peripheral blood of normal donors over a wide range of excitation and emission wavelengths. Circulating eosinophils possess three fluorescence excitation emission maxima: one at 280 nm excitation, 330 nm emission, attributable to tryptophan fluorescence, and currently unassigned peaks at 360 nm excitation, 440 nm emission and 380 nm excitation, 415 nm emission. Fluorescence microscopy studies show that the fluorescence of eosinophils may be site dependent; specifically, when observed at 365 nm excitation, circulating eosinophil fluorescence appears blue-violet, while the fluorescence of tissue-dwelling eosinophils appears amber-gold. These results should be considered in developing an optical biopsy technique to identify eosinophils in human tissue.

Cell Separation↗
PubMed1993

Conjunctival amyloidosis: is it related to trachoma?

Due to presence of trachoma in a large percentage of cases of conjunctival amyloidosis, trachoma has been blamed for causing secondary localized amyloidosis. However, there is no study to demonstrate evidence of amyloidosis in tarsoconjunctival specimens of trachomatous lids. 50 eyes of 35 patients having trachomatous eyelids with thickened tarsal plate, trichiasis and entropion had a tarsoconjunctival biopsy (3 mm x 20 mm) from the upper lid. Histopathological examination using Haematoxylin--eosin and congo red stains failed to reveal evidence of amyloid deposition in any of the biopsies. This is the first histopathological study of amyloidosis in trachomatous patients. Our study rules out the long-standing concept of trachoma having causal relationship with conjunctival amyloidosis. It is concluded that conjunctival amyloidosis occurring in trachomatous lids should be considered as primary localized amyloidosis.

Aged↗
PubMed1993

Posterior fossa surgery: an unusual cause of superficial siderosis.

With the widespread use of magnetic resonance imaging, an increasing number of cases of superficial siderosis are being discovered. However, the cause remains uncertain in almost half the cases. We report a case where previous surgery for a pontine hematoma established a pathway for extravasation of blood into the 4th ventricle, resulting in superficial siderosis that was demonstrated on a follow-up magnetic resonance imaging scan 8 years later. This case presents an unusual iatrogenic cause of superficial siderosis that has not been reported previously.

Brain Neoplasms↗
PubMed1993

Atypical sperm granuloma of the epididymis mimicking a testicular mass.

Ultrasonography (US) plays a crucial role in the evaluation of scrotal masses and is highly accurate in distinguishing extratesticular from intratesticular lesions. Occasionally, however, it may be difficult to distinguish an extratesticular process adherent to the testis from an intratesticular mass on the basis of US findings. The authors present one such unusual case, in which an epididymal sperm granuloma mimicked a testicular mass.

Adult↗
PubMed1992

Superselective angiography of a spinal dural arteriovenous fistula having a common segmental origin with the artery of Adamkiewicz.

The artery of Adamkiewicz infrequently originates from the same radicular vessel that also supplies a dural arteriovenous fistula. This variant is not adequately emphasized in the neuroradiological literature. Awareness of this entity is essential to prevent catastrophic complications during embolization. We report such a case, and our experience with attempted embolization. We are unaware of any previously reported instance of such an attempt being made.

Adult↗
PubMed1992

Pharmacokinetics of mivacurium in normal patients and in those with hepatic or renal failure.

We have determined the pharmacokinetics and duration of action of a bolus dose of mivacurium (0.15 mg kg-1) during isoflurane and nitrous oxide anaesthesia in nine patients with normal renal and liver function, nine patients undergoing cadaveric kidney transplantation and nine patients undergoing cadaveric liver transplantation. Total plasma concentrations of mivacurium were measured for 2.5 h after administration using a high-pressure liquid chromatographic assay. Plasma concentration vs time data for what were presumed to be the two active mivacurium isomers were analysed by a non-compartmental method based on statistical moments. Neuromuscular block was assessed by measuring the electromyographic evoked response of the adductor pollicis muscle to train-of-four stimulation of the ulnar nerve. The mean time to recovery of 25% neuromuscular transmission, T25, was greater in the patients with liver failure (57.2 min) than in control patients (18.7 min). The volume of distribution at steady rate (Vdss) was comparable in the three groups. Patients with impaired liver function had significantly longer mean residence time and smaller plasma clearance than did patients with renal failure or control patients. There were significant negative correlations between plasma cholinesterase activity and both T25 (r = 0.79) and mean residence time (r = 0.62).

Adult↗
PubMed1992

Ultrasonography-directed native renal biopsy: comparison of an automated biopsy device with a needle system.

The authors compared the performance of an automated biopsy device with a large-bore cutting needle system in ultrasonography-guided native renal biopsy. They retrospectively analysed 52 biopsy specimens from 50 adults with diffuse renal parenchymal disease. Twenty-six consecutive biopsy samples had been obtained manually with a 14-gauge needle (Tru-Cut, Travenol Laboratories, Deerfield, Ill.); a second set of 26 samples had been obtained with a biopsy gun (Bard Biopty, Radiplast, Uppsala, Sweden) fitted with a 14-gauge needle of similar design. The systems were compared in terms of the specimens obtained (the adequacy and the quality of tissue, the number of intact glomeruli and the presence of artifacts) and the incidence of biopsy-related complications. Biopsy specimens obtained with the biopsy gun were judged qualitatively as well as quantitatively superior; they contained an average of 17.6 intact glomeruli, whereas only 11.5 intact glomeruli were retrieved with the needle system. Although the incidence of minor complications was lower after biopsy with the automated gun than after use of the needle system (8% and 15% respectively), two major complications were observed after gun biopsy and none after needle biopsy. The results reported here indicate that for native renal biopsy the Biopty gun delivers a higher-quality tissue core with a lower frequency of minor complications, but not of major complications, than the Tru-Cut needle system.

Adult↗
PubMed1992

Diagnosis of bleeding mycotic iliac aneurysm on technetium-99m renal scan.

Since abdominal aneurysms are common in the elderly, it is not unusual to see incidental aneurysms on renal scintigraphy performed for other reasons. However, the initial discovery of a bleeding aneurysm on a renal scan in a patient with salmonella septicemia who has no other obvious focus of infection should be considered suspicious for mycotic aneurysm. A prompt diagnosis is crucial to avoid catastrophic outcome associated with delayed surgical intervention.

Aged↗
PubMed1991

Massive ischemic cerebellar infarction due to cocaine use.

This young female suffered massive unilateral infarction of the cerebellum due to cocaine use. While cocaine-associated small, asymptomatic cerebellar infarcts have been reported in the literature, massive, symptomatic cerebellar infarction attending the use of cocaine has not been previously reported.

Adult↗
PubMed1991

Chest radiographs are unreliable in predicting thrombi in the left atrium or its appendage in rheumatic mitral stenosis.

We have assessed the diagnostic accuracy of a flat or concave left mid-cardiac border (the region of the left atrial appendage) on conventional postero-anterior chest radiographs as a predictor of the presence of thrombi in the left atrium or its appendage in 80 patients with rheumatic mitral stenosis who subsequently underwent open-heart surgery. Forty-six patients (Group I) were found to have left atrial thrombus at surgery whereas 34 patients (Group II) showed no evidence of thrombosis. Only 22 of 46 patients in Group I showed a flat or concave left mid-cardiac border (sensitivity, 48%; specificity, 53%; positive predictive value, 58%). Furthermore in Group 1, the thrombus involved the left atrial appendage in 33 patients. In this subgroup only 14 patients showed a flat or concave left mid-cardiac border (sensitivity, 42%; specificity, 49%; positive predictive value, 37%). The presence of flatness or concavity in the left mid-cardiac border on conventional posterior-anterior chest radiographs in patients with rheumatic mitral stenosis is an unreliable indicator of the presence of thrombi in the left atrium or its appendage.

Adolescent↗