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Biomedical subjects

S Sen

Publications and source records attributed to S Sen.

At least 361 records · Page 20Linked to original sources
PubMed1988

Single system ureteroceles in childhood.

Fifteen patients with single system ureterocele are reviewed (three bilateral). There was an equal male: female incidence and the majority presented with a urinary tract infection. Whereas pathology was usually confined to the ureterocele-bearing renal unit, in three patients there were other major urological abnormalities. The ureteroceles were best demonstrated by ultrasonography or intravenous pyelography but the latter proved to be more sensitive, probably because there usually was sufficient function in the involved kidney. Surgical management consisted of excision of the ureterocele with ureteric reimplantation in 10 patients (12 ureteroceles) and nephro-ureterectomy in two. Four ureteroceles in three patients were managed non-operatively. Overall results of surgery were satisfactory.

Child↗
PubMed1988

Management of vesico-ureteric reflux in myelodysplasia neurogenic bladder.

During the period 1978-87, 22 patients with myelodysplasia had surgery for vesico-ureteric reflux (VUR) and seven patients with VUR were managed non-operatively. Clean intermittent catheterization was an integral part of the management in both the operated and non-operated cases. The majority of patients had reflux-related upper tract changes pre-operatively, but after operation the urinary tract was stabilized in all but one kidney which was lost. Transverse advancement ureteric reimplantation or the pull-through technique provided satisfactory results, giving a total of 29 refluxing units managed surgically.

Child↗
PubMed1988

Atrial sensing performance of AV universal pacemakers during exercise.

To investigate the atrial sensing function of dual chamber pacemakers during exercise, we studied 57 patients aged 12 to 81 years (m = 65). They were paced for sinoatrial disorders (n = 15), second or third degree AV block (n = 37), or binodal disease (n = 11). The examination was performed 3-24 months (m = 11) after pacemaker implantation. Individual sensing thresholds were determined at rest in the supine position, and proper detection of atrial signals at the programmed sensitivity level was verified during a period of 5-9 minutes (m = 5.8). Without a change in the program of the unit, symptom-limited bicycle ergometry was performed at a maximum load of 25-200 Watts (m = 95) and 6-channel chest wall electrocardiograms were continuously recorded throughout the test, including recovery. During exercise, 25/57 patients (44%) exhibited poor atrial sensing of the pulse generator; after termination of exercise in 16 of the 25 patients, proper atrial sensing resumed within 1 to 7 minutes of recovery. In the remaining nine cases, ergometry was continued after lowering the sensitivity threshold to half the initial setting or, depending on the pacemaker model, by a value of 0.4 mV. This resulted in normal function of the pulse generator in all patients but one, who needed a sensitivity adjustment of another 0.4 mV. In a subgroup of 25 patients, telemetric atrial electrogram recordings were monitored during ergometry, 19 of which could be evaluated quantitatively. Besides random atrial signal variations, presumably due to ectopic beats or runs, a systematic decrease of the peak-to-peak amplitude by 0.1 to 1.6 mV (3-30%) was observed in 16/19 patients during exercise. Mean signal reduction amounted to 11.8% and was statistically significant at the 0.1% level. It is concluded from these findings that, besides testing of atrial sensing at rest, the follow-up of dual chamber pacemakers should include an exercise test.

Adolescent↗
PubMed1988

Correlation of cardiac arrhythmias with brainstem compression in patients with intracerebral hemorrhage.

Neurogenically caused cardiac arrhythmias and their correlation to lesions within the central nervous system were examined prospectively in 54 patients with spontaneous intracerebral hemorrhage. All patients were examined neurologically daily for 3 weeks, with special attention given to signs of brainstem compression resulting from transtentorial herniation. Electrocardiograms were continuously recorded over an average of 5 days. A significant correlation was established between the clinical manifestations of brainstem compression and sinus arrhythmias, multifocal premature ventricular contractions, couplets, and ventricular tachycardias. An explanation for this correlation may be found in the localization of the autonomous cardiovascular centers in the hypothalamus and brainstem. Transtentorial herniation frequently leads to a bilateral lesion of these structures. However, the cardiac arrhythmias are only a partial phenomenon within a complex cardiovascular reaction.

Adult↗
PubMed1988

[Dose-related effect of nicainoprol (CAS 924) on basic electrophysiologic parameters in patients with and without diseases of the heart conduction system].

The dose-dependent effects of nicainoprol (1 and 2 mg/kg/h), a new antiarrhythmic drug, on invasive electrophysiological parameters were evaluated in 28 patients during diagnostic electrophysiologic studies. The most pronounced effects by nicainoprol were observed on the specialized AV conduction system. The intranodal (1 mg/kg/h: A-H interval: 92 +/- 19 ms to 107 +/- 25 ms, p less than 0.002, n = 13; 2 mg/kg/h: 92 +/- 18 ms to 114 +/- 27 ms, p less than 0.001, n = 16) and, in particular, the infranodal conduction time (1 mg/kg/h: H-V interval: 45 +/- 5 ms to 52 +/- 9 ms, p less than 0.001, n = 15; 2 mg/kg/h: 45 +/- 6 ms to 58 +/- 10 ms, p less than 0.0001, n = 18) were delayed in a dose-dependent fashion. With the higher dose, there was a highly significant prolongation of the AV nodal Wenckebach cycle length (380 +/- 69 ms to 440 +/- 79 ms, p less than 0.0001, n = 13) as well as of the effective (368 +/- 112 ms to 428 +/- 108 ms, p less than 0.001, n = 12) and functional refractory periods (470 +/- 102 ms to 521 +/- 135 ms, p less than 0.001, n = 15). The intraatrial conduction time was slightly prolonged for both doses, the intraventricular conduction time increased significantly with the higher dose (89 +/- 12 ms to 102 +/- 19 ms, p less than 0.001, n = 19). In contrast, there were only small changes of right atrial and right ventricular refractorion.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Arrhythmia Agents↗
PubMed1987

Thermodynamics of B-Z transition in supercoiled DNA.

The nature of the possible supercoil-induced B-Z transition has been analyzed from the thermodynamical point of view, by taking into account the effects of the twisting as well as the writhing components of the supercoiling free energy. The cooperative aspects of the transition, as predicted by theory, agrees well with the corresponding experimental data.

Base Composition↗
PubMed1987

High-resolution mapping of DNase I hypersensitive site in the chicken beta-tubulin gene transfected into monkey cells.

In this report, we describe a method for high-resolution mapping of a nuclease hypersensitive site (HS) at the promoter region of the chicken beta 2-tubulin gene transfected into monkey Cos-7 cells. Using the indirect end-labeling method of Wu, a tissue-specific nuclease HS was located initially approximately 100 base pairs upstream of the transcription start site. For high-resolution mapping of the HS in the transfected DNA, a DNA fragment of about 400 base pairs containing the promoter region of the beta 2 gene was subcloned into M13 phage. A single-stranded DNA probe with a defined restriction enzyme cleavage site at one end was prepared from the M13 phage DNA template. The single-stranded probe and the restriction enzyme-digested DNA, prepared from nuclease-digested nuclei from transfected cells, were sequentially annealed back to the template. After ligation between the probe and the transfected DNA, the HS was determined by DNA sequencing gel electrophoresis. This method permits determination of the 3' boundary of the HS with precision at the single-nucleotide level. We mapped a major HS at -107 nucleotides of the beta 2-tubulin gene, where a CACCC-like sequence is present. The application of this method in determining HS is discussed.

Animals↗
PubMed1987

Specific gene amplification associated with consistent chromosomal abnormality in independently established multidrug-resistant Chinese hamster ovary cells.

Multidrug-resistant (MDR) Chinese hamster ovary (CHO) cell lines were established by selection for resistance to the toxicities of vinblastine (VB) and Adriamycin (AD) in progressively increasing drug concentrations. These cell lines have amplified the DNA sequence that has previously been shown to be amplified in another MDR CHO cell line which was selected with vincristine (VC). An overproduced 4.5 kb mRNA was detected in these MDR cell lines. We report here that the levels of DNA amplification and the 4.5 kb transcript do not correlate with the levels of drug resistance, suggesting that either translational control for the expression of the amplified gene is involved or multiple genes are participating in conferring drug resistance in these cell lines. The amplified DNA sequence was used as a probe and localized by in situ hybridization to chromosome 1q 26-28 (middle portion of the long arm) in the drug-sensitive CHO line, but proximal to the telomere of chromosome 1q in both VB- and AD-selected MDR cell lines. This is consistent with results that have been previously reported for the VC-selected MDR cell lines. Cytogenetic analyses revealed abnormal chromosomal banding patterns or homogeneously staining regions (HSR) between 1q 26-28 and the 1q ter in these independently established MDR lines. These results, taken together, suggest that chromosomal rearrangements leading to gene translocation have consistently accompanied gene amplification in these MDR cell lines. The mechanisms of translocation and its implication in multidrug resistance in these cell lines are discussed.

Animals↗
PubMed1987

Role of beta 1-adrenoceptors in hypertensive cardiac hypertrophy.

Experimental and clinical evidence indicates that cardiac hypertrophy in systemic hypertension may not simply result from the mechanical stress of increased afterload. Several lines of evidence suggest that sympathetic nervous influence stimulates cardiac growth. A previous study indicated that sympathetic tone may be important in the two-kidney, one-clip model of renovascular hypertension. Hence, we investigated the role of cardiac beta-receptors by testing the effects of the cardioselective beta-receptor blocker, atenolol, on regression and prevention of ventricular hypertrophy in this model. Renal hypertensive rats were assigned to a 'prevention' and a 'reversal' protocol, receiving the drug before or after the development of hypertension and cardiac hypertrophy. Untreated control animals developed severe hypertension (205 +/- 9 mmHg) and marked cardiac hypertrophy (heart weight/body weight ratio: 3.86 +/- 0.23 mg/g) when compared to sham-operated controls (129 +/- 1 mmHg and 2.38 +/- 0.06 mg/g, respectively). Atenolol (440 mg/kg per day) failed to prevent or reverse hypertension (213 +/- 5 and 194 +/- 11 mmHg) or cardiac hypertrophy (4.10 +/- 0.39 and 3.51 +/- 0.25 mg/g, respectively). Effective beta-blockade was verified by significantly lower heart rates in treated animals (382 +/- 10 and 368 +/- 9 beats/min, respectively) than untreated controls (486 +/- 28 beats/min; P less than 0.01). Similarly, plasma renin activity returned to baseline in atenolol-treated animals. Cardiac catecholamines were markedly decreased in hypertrophied hearts (significant only for norepinephrine) and remained unaffected by atenolol treatment. However, both the prevention and reversal protocol strikingly reduced mortality in hypertensive animals (0 and 14%, respectively, versus 57%; P less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Management of double system ureterocele.

Thirty eight patients with double system ureterocele are reviewed. More than half presented in infancy, urinary infection being the commonest clinical feature. Urinary tract ultrasound (US) and renal nuclide scan (RNS) were found to be the most useful diagnostic investigations. Whereas there are various surgical options available, an analysis of the results indicates that the primary operation should usually be an upper pole heminephrourterectomy, particularly in infancy. Secondary bladder surgery will be necessary in many infants but in children with disease confined to the ureterocele segment only, bladder surgery may be avoided. In selected cases, usually beyond infancy, total one stage reconstruction with upper pole heminephroureterectomy and bladder surgery may be justified.

Child↗