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Biomedical subjects

S Rao

Publications and source records attributed to S Rao.

At least 235 records · Page 13Linked to original sources
PubMed1995

An uncontrolled trial of pefloxacin in the retreatment of patients with pulmonary tuberculosis.

OBJECTIVE: To study the role of Pefloxacin in the retreatment of pulmonary tuberculosis. DESIGN: 14 cases of sputum smear-positive tuberculosis were given pefloxacin in doses of 400 mg daily, along with isoniazid and thioacetazone plus additional drugs wherever indicated. They were followed and assessed by sputum smear microscopy and chest X-ray regularly for the total duration, which ranged from 15-18 months. RESULTS: 10 of the patients completed treatment and achieved a satisfactory response in the form of persistent sputum, negativity and radiologically quiescent disease. Two developed serious side-effects and had to discontinue medication. One patient failed on therapy as evidenced by persistent sputum positivity at 6 months. CONCLUSION: Pefloxacin may have a role in the retreatment of pulmonary tuberculosis along with other drugs, as a companion drug in selected cases. The other advantages are the low cost of treatment and high safety profile.

Adult↗
PubMed1995

Spontaneous involution of an intra-axial brain stem lesion: a case report.

This report describes the spontaneous involution of an intrinsic brain stem lesion whose clinical and MRI characteristics strongly suggest a tumor etiology. Nonoperative experiences with central nervous system tumors have shown that they may sometimes exhibit prolonged periods of dormancy. There are several reports of 'disappearing' CT lesions which have all been inflammatory, infective, or immunological. No histologically proven tumor has been shown to spontaneously involute, nor have 'disappearing' lesions been described for MRI.

Brain Neoplasms↗
PubMed1995

The high-proliferative-potential megakaryocyte mixed (HPP-Meg-Mix) cell: a trilineage murine hematopoietic progenitor with multiple growth factor responsiveness.

Megakaryocyte progenitors are notable for their response to synergistic cytokine combinations and apparently early position in the hematopoietic differentiation pathway. Although high-proliferative-potential murine megakaryocyte progenitors have been described, they have previously been primarily observed as unilineage colonies. We describe a subclass of agar-based high-proliferative-potential colony forming cells (HPP-CFC) derived from populations enriched for early hematopoietic progenitors which, when stimulated with the combination of CSF-1, G-CSF, GM-CSF, IL-1 alpha, IL-3 and SCF, produces colonies with trilineage potential for macrophages, granulocytes, and megakaryocytes. The high proliferative potential megakaryocyte mixed (HPP-Meg-Mix) colony-forming cell is defined as a cell meeting traditional criteria for HPP-CFC but additionally containing 20 or more megakaryocytes per colony. The combination of high-proliferative-potential, multilineage differentiation, and megakaryocytic lineage capacity suggests that the HPP-Meg-Mix marks a very early hematopoietic progenitor cell.

Acetylcholinesterase↗
PubMed1995

Recurrent Guillain Barre' Syndrome: a clinical, electrophysiological and morphological study.

Of the 220 patients of acute idiopathic demyelinating polyneuritis (AIDP/GBS) seen over a seven year period, 15 patients (M:F:11:4) had a relapsing course (6.8%). Their ages ranged from 8 yrs to 70 yrs. They had 36 episodes at a variable interval of 3 months to 25 yrs. Relapse rate varied from one to four. Antecedent events were noted during 16 episodes in 9 patients but the triggering factors were varied. Clinical features of individual episodes were similar to the acute monophasic illness, although they differed inseverity from one episode to the other. Autonomic disturbances were rare. Albuminocytological dissociation was observed during 19 of the 24 episodes. Electrophysiological abnormalities were observed during 19 of the 24 episodes. Electrophysiological abnormalities were present in all and were comparable with patients of non-recurrent illness. Sural nerve biopsy in 3 patients showed evidence of demyelination, remyelination, Wallerian degeneration and myelin breakdown but none had features of inflammation. With the exception of one death, functional recovery was complete in the majority of patients, irrespective of the type of therapeutic intervention. Acute onset, frequent facial involvement, brief clinical course, near complete recovery and very long asymptomatic periods may distinguish these patients of acute relapsing demyelinating polyneuropathy (ARDP) from chronic relapsing demyelinating polyneuropathy. Relapses in GBS are however unpredictable and recurrent GBS is indistinguishable clinically, electrophysiologically and morphologically from the more frequently seen non-recurrent form of monophasic GB Syndrome. A biochemical or immunological marker may help in this distinction.

Adolescent↗
PubMed1995

Acute inflammatory demyelinating neuropathy: a critical evaluation of diagnostic criteria for demyelination.

There is agreement on the clinical diagnostic criteria for acute inflammatory demyelinating polyneuropathy (AIDP/GBS) however, there is lack of consensus for detection of demyelination. In order to critically evaluate the prevailing criteria, sixty-six patients who fulfilled NINCDS criteria and had typical features of GBS were studied for electrophysiological abnormalities of peripheral nerves by using standard methods (median, common peroneal, sural and ulnar) between 1 to 12 weeks after the onset of symptoms. The commonest abnormality on motor nerve conduction study was prolonged distal latency (75%-83%) followed by reduction in CMAP amplitude (63%-82%), decreased velocity (48%-62%), conduction block (17%-39%) and f-wave abnormalities (37.8%-59%). Sensory conduction abnormalities were detected in over 20% of median, 25% of ulnar and 33% of sural nerves. All the patients had abnormality of at least two motor conduction parameters in one nerve when values beyond 2 SD of the mean were considered abnormal and over 70% of patients had three abnormalities in two nerves or two abnormalities in three nerves. Comparison with the prevailing criteria for demyelination revealed that the number of patients fulfilling them varied widely: Albers et al. (1985): 74.2%, Albers et al. (1989): 40.9% and Cornblath: 30.3%. We believe that the current criteria for detection of demyelination in acute neuropathy are too strict, underestimate the underlying pathology in GBS and need reassessment.

Adolescent↗
PubMed1994

Differential transcription of the two Saccharomyces cerevisiae genes encoding elongation factor 2.

The single polypeptide chain of elongation factor 2 (EF-2) is encoded by two Saccharomyces cerevisiae genes (EFT1 and EFT2) with unique flanking sequences. One gene is necessary and either is sufficient for cell viability. In the present work, we have analyzed the transcription of EFT1 and EFT2. Although both genes harbor multiple transcription start points, EFT1 initiates primarily at residue C at -39 and EFT2 at residue C at -37. Several candidate TATA boxes were identified in each gene. Deletion analysis employing lacZ promoter fusions demonstrated that the promoter for EFT2 is located within a 79-bp region beginning 335 nucleotides (nt) upstream from the start ATG codon. This region contains two overlapping sequences with homology to the consensus binding site for the yeast transcription factor, Rap1p/Grf1p/Tuf. In contrast, the sequences essential for the transcription of EFT1 were localized to the region between the start ATG and the stop codon of the VPS17 gene that terminates 267 nt upstream on the same strand. Analysis of promoter strengths using lacZ fusions indicated that the promoter for EFT2 is approx. 2.5-fold more active than that of EFT1. Analysis of the steady-state levels of mRNAs revealed that EFT2 contributes approx. 70% of the total EF-2 mRNA while the remaining 30% is produced by EFT1. We conclude that the difference in expression of EFT1 and EFT2 is due to the differential transcription of their promoters.

Base Sequence↗
PubMed1994

Characterization of two taxol photoaffinity analogues bearing azide and benzophenone-related photoreactive substituents in the A-ring side chain.

Taxol is a structurally novel and clinically effective antitumor drug, which, unlike other antimitotic agents, induces the assembly of tubulin into microtubules. To characterize the binding site(s) of taxol on the microtubule, taxol-based photoaffinity reagents 1 and 2 bearing photoreactive groups on the A-ring side chain were prepared and evaluated. Taxol analogue 1 exhibits better microtubule assembly activity, greater cytotoxicity toward J774.2 cells, and more specific and efficient photolabeling of the beta-subunit of tubulin than does analogue 2. Therefore, it would appear that 1 is the better candidate for further studies aimed at the characterization of the taxol binding site on the microtubule.

Affinity Labels↗
PubMed1994

Coiled-coil packing in spermine-induced tropomyosin crystals. A comparative study of three forms.

Electron microscope images of highly ordered spermine-induced microcrystals of tropomyosin have been analyzed to determine the packing of the molecular filaments. Negatively stained microcrystals terminate in a distinctive "double fringe", which reveals the location of the molecular ends. This information, together with the symmetry of the structure in projection, shows that the microcrystals can be accounted for by a packing scheme of four layers of molecules in the unit cell. Knowing the position of the symmetry elements relating the layers then allows the three-dimensional space group of the microcrystals to be established as C222(1). Using cryo-electron microscopy and simulation studies, the run of the filaments and their packing in the C222(1) form have been shown to be related to those in the spermine-induced C2 crystal of tropomyosin whose structure has been solved to 9 A by X-ray crystallography. This result allows us to infer the location of the molecular ends in the C2 crystal as well, and this inference has been confirmed by analysis of thin sections of the C2 crystal. The C222(1) microcrystal has also been shown to be closely related to the classical divalent cation tropomyosin paracrystal. Based on knowledge of the molecular packing in the divalent cation paracrystal, the polarity of the molecules has been deduced in the other two crystal forms. The tropomyosin filament packing in all these forms may be accounted for by coiled-coil close packing and specific cationic bridging of negatively charged zones on the molecule. Taken together the results reveal a hierarchy of interactions in these close-packed crystalline forms, whose principles may apply to the packing in other fibrous proteins. This study also shows the usefulness of co-ordinating results from cryo-electron microscopy with negative staining in the structure analysis of such ordered arrays, and how these findings can complement the results of low resolution X-ray crystallographic studies.

Animals↗
PubMed1994

3'-(p-azidobenzamido)taxol photolabels the N-terminal 31 amino acids of beta-tubulin.

Taxol possesses an unusual chemical structure, a unique mechanism of action, and demonstrated activity in human malignancies. It is the only antitumor agent that has a binding site on the microtubule polymer. The interaction of Taxol with the microtubule polymer results in the formation of stable bundles of cellular microtubules that are resistant to depolymerization. Although it has become evident that the microtubule, specifically beta-tubulin, is the target for Taxol, no information is available on the binding site for the drug. In this report, we demonstrate that 3'-(p-azidobenzamido)taxol, an analogue with similar biological activities as Taxol, covalently binds to the N-terminal domain of beta-tubulin after irradiation of the microtubule-drug complex. Taxol competes with [3H]3'-(p-azidobenzamido)-taxol binding, suggesting that the photoaffinity analog and Taxol are binding at the same or overlapping sites. Formic acid cleavage of [3H]3'-(p-azidobenzamido)-taxol-photolabeled beta-tubulin and subsequent protein sequence and mass analyses have identified the N-terminal 31 amino acids as the major site for [3H]3'-(p-azidobenzamido)taxol photoincorporation.

Affinity Labels↗
PubMed1994

Time parameters for glaucoma procedures.

Changes in physician reimbursement and the practice environment have emphasized the importance of determining physician time for procedures and services. Forty-five percent of the members of the American Glaucoma Society responded to a mail survey of estimates of the length of time and number of visits for the preoperative, operative, and 90-day postoperative care for six common glaucoma procedures. Results suggest a significant underestimation of time for trabeculectomies exists in the original and new resource-based relative value scale work values. Further, 47% to 53% of surgeons hospitalize patients on at least the first postoperative day. There were no apparent time efficiencies between "high-" and "low-volume" respondents. Thus, careful attention should be paid to the accuracy of certain time estimates and the resulting work values in the resource-based relative value scale. Additional work in this and other areas may prove illuminating.

Glaucoma↗
PubMed1994

Early onset Parkinson's disease: are juvenile- and young-onset different?

It is controversial if early onset Parkinson's disease (EOPD) (onset at < 41 years of age) is Parkinson's disease (PD) occurring at a younger age or a different disease. This controversy is due to some clinical and pathological differences between EOPD and PD. Within EOPD, there appear to be two groups namely: young onset Parkinson's disease (YOPD), with onset between 21 and 40 years, and juvenile parkinsonism (JP), with onset at < 20 years. The two major clinical differences between these groups are a higher familial occurrence of PD and dystonia in JP. In this study, we determine if the two groups have the classical features of PD, namely rest tremors, rigidity, bradykinesia, and postural instability, and have a meaningful response to levodopa. Furthermore, we compare their other clinical features, autonomic and cognitive functions, and levels of CSF monoamine metabolites to determine differences between these groups. We observe that all YOPD (100%) and JP (85%) patients had rest tremors. Most of these patients also had a meaningful response to levodopa (YOPD: 72%; JP: 100%). The prevalence of family history of PD was similar, whereas dystonia was more frequent in JP (43%) compared to YOPD (9%). Autonomic symptoms were twice as common in JP (42%) compared to YOPD (17%). However, bedside autonomic functions were abnormal in similar proportions and, like in PD, suggest involvement of parasympathetic nervous system. Cognitive dysfunction does occur but with no difference in severity between the two groups. The difference in number of patients between YOPD and JP groups makes statistical comparison of the occurrence of clinical features like dystonia and autonomic dysfunction difficult.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Analogue and digital instruments for non-invasive estimation of muscle fibre conduction velocity.

Analogue and digital instruments for non-invasive on-line measurement of muscle fibre conduction velocity (CV) have been designed, built and compared using test signals and real myo-electric signals. Their inputs consist of two single-differential or double-differential myo-electric signals, obtained using a three- or four-contact surface electrode system. The analogue device computes CV by tracking the lag of the zero-crossing of the cross-correlation between the first signal and the derivative of the second. The digital device computes the peak of the cross-correlation function between the two signals by sampling them at 50 KHz for 20 ms (or longer, up to 320 ms), computing CV in about 30 ms (or longer, up to about 670 ms) and resuming sampling. Both devices allow estimation of CV during either voluntary or electrically elicited contractions and include a stimulation stage and a signal conditioner with artefact suppression features. Both devices provide analogue and numerical outputs and allow interfacing with analogue and digital instrumentation. They can be used in clinical or in research environments for easy and quick identification of appropriate electrode locations and/or for monitoring CV during sustained voluntary or electrically elicited contractions. The digital version is more versatile and requires no adjustments; it provides an estimate based on intermittent reading of the signals and is more sensitive to noise and momentary CV fluctuations.

Electric Conductivity↗
PubMed1994

Nucleolar organizer regions and cervical intraepithelial neoplasia among women with human immunodeficiency virus infection.

OBJECTIVE: Our purpose was to evaluate the proliferative activity of cervical intraepithelial neoplasia lesions in human immunodeficiency virus-seropositive women. STUDY DESIGN: The proliferative activity of cervical intraepithelial neoplasia lesions was measured by nucleolar organizer regions-associated proteins count. Twenty-two biopsy specimens of cervical intraepithelial neoplasia lesions from patients positive for human immunodeficiency virus were compared with 22 matched biopsy specimens obtained from controls negative for the virus. RESULTS: The mean count of nucleolar organizer regions-associated proteins per cell was 9.5 +/- 3.7 (SD) in human immunodeficiency virus-positive patients and 7.6 +/- 2.8 in human immunodeficiency virus-negative controls (p < 0.0001 by Poisson test of heterogeneity of counts). The difference in counts between the two groups, which was confirmed by log-linear analysis, persisted within each severity stratum of cervical intraepithelial neoplasia and was independent of associated human papillomavirus infection. In human immunodeficiency virus-positive patients log-linear analysis showed that high-grade cervical intraepithelial neoplasia, the presence of human papillomavirus infection, and the severity of human immunodeficiency virus disease were independently correlated with increased nucleolar organizer regions-associated protein counts per cell. CONCLUSION: The results of this study indicate that the proliferative activity of cervical intraepithelial neoplasia lesions of human immunodeficiency virus-positive patients was increased compared with matched lesions from human immunodeficiency virus-negative women. This finding suggests the possibility of an increased oncogenic progression of cervical intraepithelial neoplasia lesions in human immunodeficiency virus-positive patients.

Adult↗
PubMed1994

Time-domain and frequency-domain analyses of the signal-averaged ECG in patients with ventricular tachycardia and ischemic versus nonischemic dilated cardiomyopathy.

The value of time-domain and frequency-domain (spectral turbulence) analyses of the signal-averaged electrocardiogram was investigated to predict induced sustained monomorphic ventricular tachycardia (VT). Two groups of patients with spontaneous nonsustained VT and left ventricular ejection fraction less than 50% were enrolled: 70 patients with idiopathic dilated cardiomyopathy (group 1) and 70 patients with ischemic heart disease (group 2). Sustained VT was induced in 9 cases (13%) in group 1 and 16 (23%) in group 2. The prevalence of abnormal time-domain and spectral turbulence analysis was 16 and 37%, respectively, in group 1 and 27 and 51%, respectively, in group 2 (NS). In group 1, the predictive accuracy of time-domain and spectral turbulence analysis for induced VT was 86 and 67%, respectively (P < .01). In group 2, the predictive accuracy of the two techniques for induced VT was, respectively, 79 and 66% (NS). In both groups, the predictive accuracy of time-domain analysis was higher than that of spectral turbulence analysis in patients with intraventricular conduction defect (IVCD): 65 versus 25%, respectively, in group 1 (P < .01), and 81 versus 44%, respectively, in group 2 (P < .05). However, the predictive accuracy of time-domain and spectral analyses was similar in patients without IVCD: 94 versus 84%, respectively, in group 1, and 77 versus 74%, respectively, in group 2. Thus, in patients with dilated cardiomyopathy, (1) the etiology does not affect the predictive accuracy of time and frequency domain and frequency-domain analyses have high predictive accuracy in patients without IVCD; and (3) spectral turbulence analysis does not improve VT prediction in patients with IVCD.

Cardiac Pacing, Artificial↗