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Biomedical subjects

A Sinha

Publications and source records attributed to A Sinha.

At least 55 records · Page 3Linked to original sources
PubMed2001

Catheter stimulation of cardiac parasympathetic nerves in humans: a novel approach to the cardiac autonomic nervous system.

BACKGROUND: Cardiac parasympathetic nerves run alongside the superior vena cava (SVC) and accumulate particularly epicardially adjacent to the orifice of the coronary sinus (CS). In animals, these nerves can be electrically stimulated inside the SVC or CS, which results in negative chronotropic/dromotropic effects and negative inotropic effects in the atria but not the ventricles. Parasympathetic nerve stimulation (PS) with 20 Hz in the CS, however, also excites the atria, thereby inducing atrial fibrillation. The present study overcomes this limitation by applying high-frequency nerve stimuli within the atrial refractory period. Using this technique, we investigated for the first time whether neurophysiological effects similar to those in animals can be obtained in humans. METHODS AND RESULTS: In 25 patients, parasympathetic nerves were stimulated via a multipolar electrode catheter placed in the SVC (stimulation with 20 Hz; n=14) or CS (pulsed 200-Hz stimuli; n=11). A significant sinus rate decrease and prolongation of the antegrade Wenckebach period was achieved during PS in the SVC. During PS in the CS, a graded-response prolongation of the antegrade Wenckebach interval was observed with increasing PS voltage until third-degree AV block occurred in 8 of 11 patients. The negative chronotropic/dromotropic effects started and terminated immediately after the onset and termination of PS, respectively. Atropine abolished these effects (n=11). CONCLUSIONS: Human parasympathetic efferent nerve stimulation induces reversible negative chronotropic and dromotropic effects. PS may serve as an adjunctive tool for the diagnosis/treatment of supraventricular tachycardias and may be beneficial for ventricular rate slowing during tachycardic atrial fibrillation in patients with congestive heart failure.

Arrhythmias, Cardiac↗
PubMed2001

The BMP family member Gdf7 is required for seminal vesicle growth, branching morphogenesis, and cytodifferentiation.

Epithelial-mesenchymal interactions play an important role in the development of many different organs and tissues. The secretory glands of the male reproductive system, including the prostate and seminal vesicles, are derived from epithelial precursors. Signals from the underlying mesenchyme are required for normal growth, branching, and differentiation of the seminal vesicle epithelium. Here, we show that a member of the BMP family, Gdf7, is required for normal seminal vesicle development. Expression and tissue recombination experiments suggest that Gdf7 is a mesenchymal signal that acts in a paracrine fashion to control the differentiation of the seminal vesicle epithelium.

Animals↗
PubMed2001

Improving diabetes care in the primary healthcare setting: a randomised cluster trial in remote Indigenous communities.

OBJECTIVE: To evaluate a system for improving diabetes care in remote Indigenous communities. DESIGN: Randomised, unblinded cluster trial over one year (1 March to 29 February 2000). PARTICIPANTS AND SETTING: Primary healthcare staff in 21 primary healthcare centres in the Torres Strait and Northern Peninsula Area (NPA) Health Service District, north Queensland, and 678 people with diabetes, mostly Torres Strait Islanders. INTERVENTION: Diabetes recall system established at eight of the 21 sites, as well as staff training in basic diabetes care, regular phone calls from the project officer, a two-monthly newsletter and a mid-project workshop. MAIN OUTCOME MEASURES: Regular checks of weight, blood pressure, eye and foot care, serum lipid levels and glucose monitoring and control, urinary albumin to creatinine ratio and serum creatinine levels, and administration of recommended vaccines; hospitalisation in the previous 12 months. RESULTS: There was improvement in most measures at most sites, except for blood pressure monitoring and control, and vaccination status. Intervention sites showed greater improvement in most indicators than control sites (combined relative risk [RR], 1.21; 95% CI, 1.03-1.43). The intervention group showed a 32% reduction in hospital admissions for diabetes-related conditions over the study period (P=0.012). At follow-up, patients in intervention sites were 40% less likely to be hospitalised for a diabetes-related condition than those in control sites (RR, 0.60; 95% CI, 0.41-0.86; P=0.007). CONCLUSION: A simple recall system, managed by local healthcare workers and supported by a diabetes outreach service, achieved significant improvements in diabetes care and reduced hospitalisations in a high-risk population.

Diabetes Mellitus↗
PubMed2001

A critique of the new ST-segment criteria for the diagnosis of acute myocardial infarction in patients with left bundle-branch block.

BACKGROUND: Recently, electrocardiogram (ECG) criteria have been proposed for the diagnosis of acute myocardial infarction (AMI) in the presence of left bundle-branch block (LBBB). However, clinical experience indicates that such ECG changes indicative of AMI are occasionally noted in clinically stable patients with LBBB, raising concerns about the specificity of the proposed criteria. HYPOTHESIS: The aim of this study was to evaluate the frequency of ST-segment abnormalities suggestive of AMI in ambulatory patients with cardiovascular disease and chronic LBBB, who did not have an AMI. In addition, the ECG determinants of such ST-segment abnormalities were sought. METHODS: The files of all (4,193) patients followed in the outpatient cardiology clinic were reviewed to identify patients with LBBB. Electrocardiograms of these patients were evaluated as to the duration of the QRS complex, frontal QRS axis, amplitude of QRS in leads V1-V3, and the presence and magnitude of ST-segment depression (-ST) in leads V1-V3, and ST-segment elevation (+ST) in leads with predominantly positive or negative QRS complexes. Correlations of these ECG variables were carried out. RESULTS: In 124 patients with LBBB only 1 patient with -ST of 1 mm in leads V1-V3, and 1 patient with +ST of 1 mm in a predominantly positive ECG lead were found; the latter patient also had +ST of 6 mm in V3. Nine patients were detected with > or = 5 mm +ST in at least one ECG lead with predominantly negative QRS complex. Regression analysis of amplitude of +STs on corresponding QRS amplitudes in leads V1-V3 yielded Rs of 0.69, 0.68, and 0.69, all with a p value of 0.00005. A similar analysis of the amplitudes of +STs > or = 5 mm with the corresponding QRSs yielded an R = 0.76 and a p value of 0.0018. CONCLUSIONS: Thus, recently proposed ST-segment criteria for the diagnosis of AMI in patients with LBBB are appropriate. However, stable > or = 5 mm +STs are occasionally found in leads with predominantly negative QRS complexes, particularly of large amplitude (mean value 46.0, range [28.0-71.0] mm) in the absence of AMI. In such patients presenting with symptoms suggestive of AMI, further non-ECG confirmation of probable underlying AMI should be sought.

Adult↗
PubMed2001

Reinfusion of drained blood as an alternative to homologous blood transfusion after total knee replacement.

In patients undergoing total knee replacement we carried out a longitudinal cohort study to determine the efficacy and safety of a postoperative autologous blood reinfusion system, as an alternative to homologous, banked blood transfusions. Fifty patients received reinfusion of unwashed, filtered, shed blood, supplemented with banked blood transfusions as required. A control group of 50 patients in whom standard suction drains were used received homologous blood transfusions as required. In the study group, the homologous blood requirement was reduced by 80%. There was no significant difference in the postoperative haemoglobin values between the two groups. None of the patients developed any adverse reactions after reinfusion.

Adult↗
PubMed2001

Information content of volume holographic imaging.

We discuss the general properties of optical imaging in three-dimensional object domains from an information-theoretic standpoint, expressing system performance in terms of imaging mutual information (IMI). We use IMI to characterize volume holographic imaging, a new optical imaging method with depth discrimination capability. The performance of this holographic method in imaging a simple discrete, axial fluorescent object is compared with that of two alternatives: a pinhole-based system and a combined system that uses both a pinhole and a hologram in parallel.

Holography↗
PubMed2001

The use of a vertical infraclavicular brachial plexus block in a patient with myasthenia gravis: effects on lung function.

A patient who was suffering an exacerbation of myasthenia gravis dislocated her elbow. She underwent closed reduction of the dislocation under vertical infraclavicular brachial plexus blockade. The technique was successful but was associated with a 29% decrease in forced vital capacity, from 1.7 l to 1.2 l. The patient did not show any symptoms of ventilatory failure. Her recovery was uncomplicated.

Anesthesia, Conduction↗
PubMed2001

Impaired platelet prostacyclin receptor activity: a monozygotic twin study discordant for spinal cord injury.

Coronary artery disease (CAD) has been reported to occur prematurely in individuals with spinal cord injury (SCI). Although persons with SCI have metabolic abnormalities that may predispose them to CAD, other potential aetiologies may also be operative. Increased platelet aggregation, among other factors, initiates thrombus formation at the site of the vessel injury, which may acutely obstruct arterial blood flow. Prostacyclin is known to have a beneficial effect to inhibit platelet aggregation and prevent thrombus formation. Platelets were studied from 12 pairs of monozygotic twins, one co-twin with SCI. Each twin pair had similar patterns of platelet aggregation with adenosine diphosphate (ADP), thrombin or collagen, as well as inhibition of platelet aggregation by prostacyclin (PGE1/I2) and synthesis of cyclic adenosine mono phosphate (AMP) by the prostanoid. However, the twin pairs differed in their response to PGE1/I2 inhibition of platelet-stimulated thrombin generation that was completely inhibited in non-SCI platelets but not in SCI platelets. Scatchard analysis of the binding of 3H-prostaglandin E1, a stable prostacyclin receptor probe, showed the presence of one high-affinity (Kd1=8.1 +/- 2.8 nM; nl=168 +/- 35 sites per platelet) and one low-affinity (Kd2=1.1 +/- 0.22 microM; n2=1772 +/- 220 sites per cell) prostacyclin receptor in normal platelets, whereas in SCI platelets there was a significant loss (P<0.00l) of high-affinity receptor sites (Kd1=6.34 +/- 1.80 nM; n1=42 +/- 11 sites per platelet) with no significant change in the low-affinity receptor sites (Kd2=1.2 +/- 0.23 microM; n2=1860 +/- 412 sites per cell). These discordant platelet findings in identical twin pairs raises the possibility of an environmental aetiology for accelerated CAD in those with SCI. The loss of inhibitory effect of PGI2 on thrombin generation in the twin with SCI appears to be because of loss of platelet high-affinity prostanoid receptors, which may contribute to atherogenesis in individuals with SCI.

Alprostadil↗
PubMed2001

Diagnosis of myocardial infarction-induced ventricular aneurysm in the presence of complete left bundle branch block.

An analysis of the 4,196 files of our Cardiology Clinic cohort showed 128 patients with a complete left bundle branch block (LBBB) in their electrocardiograms (ECGs). Of these patients, 27 had suffered a myocardial infarction in the past and had been found to have a ventricular aneurysm (VA), documented by > or = 1 of several noninvasive and invasive diagnostic methods. Five of these 27 patients had stable ST-segment elevation in > or = 1 of left precordial ECG leads, with predominantly positive QRS complexes (an ECG criterion for the diagnosis of VA in the presence of LBBB, which we have recently described). The sensitivity of this ECG criterion for the diagnosis of VA was 18.5%, and the specificity was 100%. The frequency of distribution of VA in the septal, and even more, apical myocardial regions was higher in the patients with a positive ECG diagnosis of VA, than in the patients with a negative one (P = .049, and P = .009, correspondingly). The number of myocardial territories involved with a VA was not different in the 2 subgroups (P =.325). Pathophysiologically, this ECG alteration diagnostic of VA represents a superimposition of the primary ST-segment elevation due to the VA, on the expected secondary ST-segment depression due to the LBBB, and represents a summation effect.

Aged↗
PubMed2001

Gravid uterus in an incisional hernia.

A case of gravid uterus in an incisional hernia is reported. The pregnancy was further complicated by intrauterine growth restriction, oligohydramnios and pregnancy induced hypertension. The management of the case is discussed.

Adult↗
PubMed2001

Dysphagia and thoracoabdominal aneurysm.

Two elderly patients who presented with gradually progressive dysphagia are described. Investigations excluded an intraluminal obstruction and showed extrinsic compression of the oesophagus by an aneurysmal aorta. Surgery was not performed and they were successfully managed with a liquid diet.

Aged↗