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S Shukla

Publications and source records attributed to S Shukla.

At least 37 records · Page 2Linked to original sources
PubMed2001

Posterolateral tunnels and ponticuli in human atlas vertebrae.

The posterolateral tunnel on the superior surface of the first cervical (atlas) vertebra is of normal occurrence in monkeys and other lower animals, but its presence in the form of a tunnel-like canal, for the passage of the third part of the vertebral artery over the posterior arch of the human atlas vertebra is not reported. The aim of the present study was to detect the presence of such a canal, in addition to other types of ponticuli (little bridges) reported by earlier investigators, in macerated atlas vertebrae and routine cadaveric dissections. The posterolateral tunnel was detected in 1.14%, and the posterior and lateral ponticuli in 6.57 and 2% of vertebrae. Probably the bony roof of the posterolateral tunnel serves the purpose of additional lateral extension for the attachment of the posterior atlanto-occipital membrane in quadrupeds, where the load of the head is supported by the extensor muscles of the neck, ligaments and posterior atlanto-occipital membrane. In man, where the weight of the head is borne by the vertical loading of the superior articular process of the atlas, the roof of the tunnel has disappeared.

Adult↗
PubMed2001

Synthesis and characterization of nanocrystalline silver coating of fly ash cenosphere particles by electroless process.

Electroless nanocrystalline Ag coating of fly ash cenosphere particles utilizing a Sn-Pd catalyst system is demonstrated in this article. The deposition of pure metallic nanocrystalline Ag on the fly ash cenosphere particle surface is confirmed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) analysis. Under the described conditions of electroless coating, average nanocrystalline Ag-coating thickness is observed to be approximately 220 nm, using a focused ion beam technique, which is less than that observed by transmission electron microscopy (TEM) (260-360 nm). TEM observation further reveals that the Ag-coating is made up of 50 nm Ag nanocrystallites, which is comparable with the size of approximately 37 nm obtained from the XRD data. The mechanism of the electroless Ag-coating process is discussed. Ag-coated fly ash particles find applications in manufacturing conducting polymers for electromagnetic interference shielding applications.

Carbon↗
PubMed2000

Effect of calcium channel blockers on baroreceptor reflex in anaesthetized cats.

The baroreflex-induced changes in heart rate in chloralose anaesthetized and artificially ventilated cats (2.5-4.0 kg) before and after pretreatment with calcium channel blockers (CCBs) were compared. Baroreflex mediated changes in heart rate (HR) were elicited by raising and lowering the systemic blood pressure with intravenous injections of phenylephrine and sodium nitroprusside, respectively. The effects of three CCBs, verapamil, diltiazem and nifedipine administered either intravenously (i.v.) or intracisternally (i.c.) were studied. Verapamil administration markedly inhibited the reflex bradycardia as well as the tachycardia following either i.v. or i.c. administration. Intracisternally, a relatively smaller dose of verapamil produced an effect comparable in magnitude and duration, to a higher i.v. dose. The reflex bradycardia was inhibited following i.v., but not i.c. administration of nifedipine while the reflex tachycardia was not affected significantly by either i.v. or i.c. nifedipine. Intravenous diltiazem did not appear to affect the reflex bradycardia or tachycardia significantly. It is suggested that verapamil administration interacts with central cardiovascular integrating mechanisms to reduce the gain of the baroreflex function. Nifedipine and diltiazem are relatively free from this effect.

Animals↗
PubMed2000

Factors influencing pain outcome in herpes zoster: an observational study with valaciclovir. Valaciclovir International Zoster Assessment Group (VIZA).

AIM OF THE STUDY: An observational study with valaciclovir was conducted to assess clinical outcome in herpes zoster, especially pain and associated neurological signs and symptoms in relation to a series of demographic and disease characteristics discernible at presentation. The safety and acceptability of valaciclovir for treatment of zoster was assessed in a wide variety of primary care and clinic referral settings. METHODS: In total, 1897 immunocompetent adults with clinically diagnosed, localized acute herpes zoster were enrolled in this international, open-label study of valaciclovir. All subjects received treatment with oral valaciclovir (1000 mg three times daily) for 7 days from entry to the study and were asked to record the presence of zoster-associated pain and abnormal sensations throughout treatment and 6 months' follow-up. They were seen frequently in clinic to verify subjective assessments and for evaluation of rash healing. Safety and tolerability were assessed by adverse event monitoring. RESULTS: Overall, 1191 subjects (63%) were aged > or = 50 years, and 203 (11%) had ophthalmic zoster. Cessation of zoster-associated pain was significantly faster in the younger age group; median times to loss of zoster-associated pain were 23 days and 9 days in the > or = 50 and < 50 years age groups, respectively. Similarly, abnormal sensations resolved significantly more rapidly in the younger subjects; the median duration of abnormal sensations was 31 days in the > or = 50 year olds and 16 days in those aged < 50 years. In cases of ophthalmic zoster, the rate of pain resolution was not different from those with zoster in other dermatomes (median duration of pain 18 vs. 16 days). However, abnormal sensations persisted significantly longer in subjects with ophthalmic zoster than in those with zoster at other sites (47 vs. 22 days). In addition to advancing age, subjects suffering moderate to severe prodromal pain or acute pain during the rash phase were at significantly greater risk of zoster-associated pain and abnormal sensations persisting for longer. Subjects with concomitant neurological disorders were also more likely to develop prolonged abnormal sensations. Valaciclovir treatment was well tolerated, and adverse events were rare and generally mild. CONCLUSION: This study confirmed the prognostic importance of advancing age and the intensity of prodromal or acute pain as risk factors for prolonged zoster-associated pain and persisting abnormal sensations in the affected dermatome. Ophthalmic zoster and pre-existing neurological disorders are also identified as highly significant risk factors for prolonged abnormal sensations in herpes zoster.

Acyclovir↗
PubMed2000

Analyzing the multiple functions of stereotypical behavior for students with autism: implications for assessment and treatment.

We studied behavioral functions associated with stereotypical responses for students with autism. In Study 1, analogue functional analyses (attention, demand, no-attention, and recreation conditions) were conducted for 5 students. Results suggested that stereotypy was multiply determined or occurred across all assessment conditions. For 2 students, stereotypy was associated with positive and negative reinforcement and the absence of environmental stimulation. For 2 other students, stereotypy occurred at high levels across all experimental conditions. For the 5th student, stereotypy was associated with negative reinforcement and the absence of environmental stimulation. In Study 2, the stereotypy of 1 student was further analyzed on a function-by-function basis. Within a concurrent-schedules procedure, alternative responses were taught to the student using functional communication training. The results of Study 2 showed that similar topographies of stereotypy, based on qualitatively different reinforcers, were reduced only when differential reinforcement contingencies for alternative forms of communication were implemented for specific response-reinforcer relations. Our results suggest that the causes of stereotypy for students with autism are complex and that the presumed association between response topography and behavioral function may be less important than previously realized.

Adolescent↗
PubMed2000

Comparative effectiveness of Tiron (4,5-dihydroxy benzene 1,3-disulphonic acid disodium salt) and CaNa2EDTA with time after beryllium poisoning.

The efficacy of two chelating agents (Tiron and calcium disodium EDTA) in the treatment of beryllium induced blood biochemistry and hepatic histopathological alteration was investigated at different duration in female albino rats. Single administration of beryllium nitrate at a dose of 50 mg/kg (im) showed significant decrease in haemoglobin percentage, blood sugar level, protein contents and activity of alkaline phosphatase. On the contrary significant elevation was found in the activity of transaminases (AST and ALT). Tiron was found to be more effective than CaNa2EDTA in reducing the beryllium induced haematological alterations and histopathological lesions in liver. These findings were further confirmed by AAS thus, in which reduced beryllium body burden was seen in liver and blood with Tiron.

1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium ↗
PubMed1998

Treatment of acute herpes zoster: effect of early (< 48 h) versus late (48-72 h) therapy with acyclovir and valaciclovir on prolonged pain.

The efficacy of early versus late treatment with acyclovir and valaciclovir on zoster-associated pain was assessed from two databases (1076 patients) that were compiled from randomized trials. Early treatment was started < 48 h and late treatment was started 48-72 h after the onset of cutaneous herpes zoster. Median times to complete resolution of zoster-associated pain were 28 and 62 days, respectively, for patients (> or = 18 years of age) treated with acyclovir and placebo within 48 h (hazard ratio [HR], 1.68; 95% confidence limit [95% CL], 1.19, 2.38) and 28 and 58 days, respectively, for those treated later (HR, 2.20; 95% CL, 1.03, 4.71). In the valaciclovir versus acyclovir study (in patients > or = 50 years of age), the corresponding figures were 44 and 51 days for patients treated early (HR, 1.28; 95% CL, 1.03, 1.60) and 36 and 48 days for those treated later (HR, 1.40; 95% CL, 1.04, 1.87). Acyclovir significantly shortened the time to complete resolution of zoster-associated pain compared with placebo (and valaciclovir was superior to acyclovir in this regard) even when therapy was delayed up to 72 h after rash onset.

Acute Disease↗
PubMed1998

The identification of risk factors associated with persistent pain following herpes zoster.

Demographic and clinical characteristics of patients with herpes zoster at the time of presentation predict the duration and severity of pain on long-term follow-up. Analyses by Cox's proportional hazard models of six databases from controlled trials of antiviral drugs (total subjects = 2367) identified covariates for zoster-associated pain; all tests for significance were two-sided. Age strongly influenced pain outcome: patients > or = 50 years old were significantly more likely to have prolonged zoster-associated pain compared with those < 30 years old. Patients with prodromal symptoms or moderate or severe pain at presentation were also more likely to experience prolonged zoster-associated pain. Neither time to initiating treatment after rash onset nor sex of patient influenced pain outcome. Advancing age, prodromal symptoms, and acute pain severity at presentation predicted those individuals most at risk of prolonged pain and postherpetic neuralgia. When two or more of these factors were present, the risk of persistent pain was increased.

Adult↗
PubMed1998

A randomized controlled trial of acyclovir versus netivudine for treatment of herpes zoster. International Zoster Study Group.

Oral acyclovir has become the standard of care for treatment of acute herpes zoster. Netivudine is a novel antiviral with greater in-vitro activity against varicella zoster virus. It was compared with acyclovir in a randomized, double-blind, controlled trial in immunocompetent adults with herpes zoster. Patients with rash for less than 72 h were assigned to receive either acyclovir or netivudine, then assessed regularly for 6 months. No evidence for a dose response with netivudine was found, so intent-to-treat analyses of all 511 enrolled patients compared acyclovir with netivudine. The time to complete cessation of pain (P = 0.007) and to cessation of moderate to excruciating pain (P = 0.005) was accelerated in acyclovir recipients. Rash outcomes and adverse event profiles were similar for both treatments. This study has confirmed the efficacy of acyclovir in decreasing the duration and severity of pain following herpes zoster. Greater in-vitro activity of newer agents may not necessarily provide greater benefit in humans.

Acyclovir↗
PubMed1998

A multiresolution restoration method for cardiac SPECT imaging.

In this study we present a multiresolution based method for restoring cardiac SPECT projections. Original projections were decomposed into a set of sub-band frequency images by using analyzing functions localized in both the space and frequency domain. This representation allows a simple denoising and restoration procedure by discarding high-frequency channels and performing inversion only in low frequencies. The method was evaluated in bull's eye reconstructions of a realistic cardiac chest phantom with a custom-made liver insert and 99mTc liver-to-heart activity ratios (LHAR) of 0:1, 1.5:1, 2.5:1, and 3.5:1. The cardiac phantom in free air was used as the reference standard. Reconstructions were performed by filtered backprojection using (1) no correction; (2) restoration without attenuation correction; (3) attenuation correction without restoration; and (4) restoration and attenuation correction. The attenuation correction was carried out with the Chang's method for one iteration. Results were compared with those obtained using an optimized prereconstruction Metz filter. Quantitative analysis was performed by calculating the normalized chi-square measure and mean +/- s.d. of bull's eye counts. In reconstructions with high liver activity (LHAR > 2), attenuation correction without restoration severely distorted the polar maps due to the spill-over of liver activity into the inferior myocardial wall. Both restoration methods when combined with an attenuation correction compensated this artifact and yielded uniform polar maps similar to that of the standard reference. There was no visual or quantitative difference between the performance of Metz filtering and multiresolution restoration. However, the main advantage of the multiresolution method is that it states a more concise and straightforward approach to the restoration problem. Multiresolution based methods does not require information about the object image or optimization processes, such as in conventional nuclear medicine restoration filters. In addition, the method is easy to implement using DFT techniques and potentially can be extended to noniterative spatially shift-invariant restorations in SPECT.

Biophysical Phenomena↗
PubMed1998

Anti-inflammatory benzopyran-2-ones and their active oxygen species (aos) scavenging activity.

Benzopyrano derivatives were synthesized and evaluated for their anti-inflammatory, ulcerogenic activities and toxicity studies. The in-vitro studies comprised of anti-proteolytic activity, lipid peroxidation inhibitory and reducing activities against alpha, alpha-diphenyl-beta-picrylhydrazyl (DPPH). Two potent compounds were studied further for their inhibition of lipid peroxidation and effect on Superoxide dismutase (SOD) activity in-vivo. These compounds were found promising in all the parameters studied, thereby signifying inter-relationship between their anti-inflammatory activity and anti-oxidant properties.

Animals↗
PubMed1997

Gamma camera imaging of osseous metastatic lesions by strontium-89 bremsstrahlung.

The aim of this study was to optimise the parameters affecting the Bremsstrahlung scintigraphy of patients injected with strontium-89 chloride. The parameters considered were : (1) instrumental detection efficiency, and (2) tissue attenuation factor for 89Sr calibrated sources, which permit quantitative evaluation of the activity in a given bone lesion. Some typical examples of in vivo 89Sr imaging are presented to illustrate the clinical utility of the imaging procedure developed by us, which is implemented in our department for all patients treated with 89Sr chloride.

Bone Neoplasms↗
PubMed1997

Multiple infected extradural parasellar hydatid cysts.

BACKGROUND: Intracranial hydatid disease constitutes 1%-2% of all cases of hydatid disease. Multiple, infected, extradural, parasellar hydatid cysts in a patient constitutes an extremely rare presentation. CASE REPORT: This 21-year-old man presented with a progressive left supraclavicular swelling of 3 years duration and raised intracranial pressure of 6 months duration with a past history of left-sided chronic suppurative otitis media that had resolved with antibiotics. On neurologic examination, he had bilateral deterioration of vision with optic atrophy; right temporal field defect; left III, IV, VI, VI, and V2 cranial nerves palsy; and left ear conductive deafness. The patient's E.S.R was raised. His computed tomography (CT) scan showed a hypodense, lobulated lesion in the middle cranial fossa with a hypodense, nonenhancing rim, septations, and focal calcification without perifocal edema. A purulent fluid was aspirated from the left supraclavicular swelling, which did not reveal any organism on staining and culture. Aspiration of the left temporal swelling showed whitish watery fluid, the cytology of which revealed an infected hydatid cyst. Excision of the left temporal extradural, hydatid cysts was done, except the portion of the capsule adherent to the dura, and albendazole was started. One month later, the supraclavicular hydatid cysts were removed. Six months later, a left mastoidectomy was performed for chronic suppurative otitis media. A repeat CT scan showed complete resolution of the hydatid cysts. There was no recurrence at 1 year follow-up. CONCLUSIONS: A rare case of multiple infected extradural hydatid cysts of the parasellar region is reported. The unusual CT picture of a hypodense lobulated mass with septations and a hyperdense rims is presented. The difficulties in its complete excision and successful management with long-term albendazole therapy are discussed.

Adult↗
PubMed1997

The glycoprotein IIb/IIIa antagonist c7E3 inhibits platelet aggregation in the presence of heparin-associated antibodies.

PURPOSE: Heparin-associated antibodies (HAAb), in the presence of heparin, can cause platelet activation and aggregation. The purpose of this study was to assess whether a platelet glycoprotein (GP) IIb/IIIa receptor antagonist, c7E3, would inhibit platelet aggregation in the presence of HAAb. If aggregation is inhibited by c7E3, enzyme-linked immunosorbent assays (ELISA) would be done to determine whether c7E3 interfered with the binding of heparin and the HAAb. METHODS: HAAb-positive plasmas from 21 patients (determined by platelet aggregation assays) were studied. Normal donor platelet-rich plasmas (PRP) were incubated (1 minute) with either saline solution or 3 microg/ml of c7E3. Platelet-poor plasma from patients with HAAb and one of three sources of heparin (25 microl, 10 U/ml; porcine heparin, bovine heparin, and low molecular weight heparin [enoxaparin]) were added to the PRP mixture. Aggregation was determined using a platelet aggregometer by measuring time to aggregation, the slope of the aggregation curve, and the percent change in optical density. RESULTS: Platelet aggregation occured in 100%, 100%, and 95% of the saline solution incubations exposed to porcine heparin, bovine heparin, and enoxaparin, respectively. Incubation with c7E3 caused 100% inhibition of platelet aggregation in plasma exposed to porcine heparin, bovine heparin, and enoxaparin. The optical density curves obtained from the ELISA, which were dependent on the binding of HAAb to heparin, were not significantly different when c7E3 was compared to buffer alone. CONCLUSIONS: The GP IIb/IIIa receptor antagonist, c7E3, inhibits HAAb-induced platelet aggregation via a mechanism that does not appear to interfere with the binding between heparin and HAAb. Clinical trials are warranted to assess whether GP IIb/IIIa antagonists may allow patients with HAAb to safely receive heparin.

Abciximab↗
PubMed1997

100 years of Widal test & its reappraisal in an endemic area.

A reappraisal of the Widal test was made for its diagnostic utility in typhoid fever in an endemic area of Central India. The significant basal antibody level in the normal population based on 1200 voluntary/relative blood donors at the cut-off titre of 80 or above was observed in 13.83 and 8.0 per cent for 'O' and 'H' antigens of Salmonella typhi respectively. A retrospective study (1991-1995) over 138 bacteriologically proven cases of typhoid showed a positivity of 64.49 and 78.26 per cent respectively for 'O' and 'H' antibodies at the titre of 80 or above and 44.2 and 63.04 per cent at the titre of 160 and above. The retrospective data also showed a greater positivity (46.41%) in 1991 which decreased to 25 per cent in 1995 and appeared to follow the incidence of multi drug resistant S. typhi over the period. The detection of 'H' antibodies is no less important than the 'O' antibodies in the present study. Our data bring out the diagnostic limitations of Widal test done on single samples collected in the early phase of illness (4-10 days) from patients suspected to have typhoid in an endemic area of Central India.

Antigens, Bacterial↗
PubMed1997

Haemagglutination system for the simultaneous detection of LPS and anti LPS antibodies of S.typhi.

In view of the limitations of Widal test for the diagnosis of typhoid, haemagglutination test using sensitized sheep red blood cells was designed at our laboratory. The test gave only 1.8% positivity at 1:40 dilution among 500 normal persons. Eighteen of the 30 culture proven cases gave the HA test positive while the positivity was 62.5% among suspected cases of typhoid. Thus, the anti LPS haemagglutination test showed a sensitivity of 60% and specificity of 98.2%. The positive predictive value and negative predictive value were 66.66% and 96.7% respectively. The haemagglutination inhibition test was also developed for the detection of LPS antigen of S. typhi in the serum samples of typhoid cases and could detect 1.5625 micrograms/ mL of S. typhi LPS antigen but failed to detect LPS in the sera of bacteriologically proven cases of typhoid. However, it could detect the growth of simulated blood cultures of S. typhi within one hour of inoculation and did not give any cross reactions with other bacterial cultures. The data suggest that the haemagglutination test could be a good adjunct for Widal test and the haemagglutination inhibition test could help the early detection of S. typhi in culture.

Antibodies, Bacterial↗
PubMed1996

Role of platelet-activating factor in skeletal muscle ischemia-reperfusion injury.

These studies indicate that PAF, a known stimulator of aggregation, secretory and/or contractile activity of platelets, neutrophils, smooth muscle and other cells, is produced by skeletal muscle during IRI. The maximum increase occurs at 10 to 15 minutes and continues for at least an hour. Infusions of PAF into skeletal muscle subjected to 20 minutes of ischemia and 20 hours of reperfusion resulted in tissue necrosis similar to that produced by 5 hours of ischemia and 20 hours of reperfusion. 25 mg/kg of pentoxifylline, infused immediately prior to reperfusion of ischemic skeletal muscle, decreased PAF production and muscle necrosis. It was also demonstrated that skeletal muscle necrosis can be reduced by infusion of PAF antagonists (WEB-2086) into the muscle immediately prior to reperfusion. Thus, PAF has an important role in skeletal muscle IRI and additional studies of PAF inhibition during IRI are warranted.

Animals↗