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Biomedical subjects

A Joshi

Publications and source records attributed to A Joshi.

At least 55 records · Page 3Linked to original sources
PubMed2002

Efficacy of erbium YAG laser-assisted autologous epidermal grafting in vitiligo.

BACKGROUND: Of the various modalities of therapy available for the treatment of vitiligo, a combination of psoralen + ultraviolet A (PUVA) with autologous epidermal grafting appears to offer the best results. The erbium YAG laser can be used to prepare the recipient site in both punch grafting and suction blister grafting. METHODS: In this study 29 subjects, 26 with localized and three with generalized stable vitiligo, had received pregrafting PUVA and underwent further PUVA starting 2 weeks after surgery until maximal pigmentation was achieved. The erbium YAG laser was used on 16 subjects; the recipient site for punch grafting was prepared with laser and minigrafts harvested by manual punch were placed into the prepared sites. For suction blister grafting, the site was dermabraded with a laser and the harvested blister roof (created using suction apparatus) was transplanted on to the site. RESULTS: More than two-thirds (68.75%) of the subjects who were punch grafted using a laser showed repigmentation of more than 75%, but only one-half of those who underwent conventional punch grafting showed a similar response. All subjects with laser-assisted suction blister grafting showed a good response, compared with only 60% of those who underwent conventional suction blister grafting. CONCLUSIONS: The results obtained with laser-assisted grafting are more satisfactory than those achieved with conventional grafting techniques. We found that the repigmentation zones are larger (up to 9 mm in the former vs. 3 mm in the latter) and cobblestoning does not occur with laser-assisted grafting. Also, the procedure is precise, relatively atraumatic and can be performed rapidly even when covering vast areas.

Adolescent↗
PubMed2002

External neurolysis of the lingual nerve.

The lingual nerve is sometimes injured during the surgical removal of an impacted mandibular third molar. The level of sensory recovery was studied in 10 patients who underwent external neurolysis of the lingual nerve. The mean time from third molar surgery to neurolysis was 13.5 months (range 9-24 months). Seven of the 10 patients showed significant improvement, three patients regaining normal sensation. Three patients showed no improvement. These results show that external neurolysis should be considered for patients with altered sensation in the distribution of the lingual nerve.

Cranial Nerve Injuries↗
PubMed2002

Cerebral malaria in Indian adults: a prospective study of 441 patients from Bikaner, north-west India.

AIMS OF THE STUDY: As per WHO (1993) the assessment and analysis of local problems and an appropriate epidemiological information system is an essential part of a control programme before embarking any control activity. METHODOLOGY: Four hundred and fourty one (441) adults of strictly defined admitted cerebral malaria patients were studied. Detailed clinical/neurological examination was done at the time of admission, daily thereafter, at the time of regaining consciousness, at the time of discharge and at weekly intervals in those having neurological sequelae. All patients were treated by i.v./oral quinine and specific syndromes were managed according to WHO guidelines. RESULTS: Apart from fever and unconsciousness in all the patients, other features were convulsion (21.31%), neck rigidity (19%), psychosis (5.21%), conjugate deviation of eyes (2.26%), extrapyramidal rigidity (2.25%), trismus (1.31%), decorticate rigidity (1.13%) and decerebrate rigidity (0.90%). One hundred forty five (32.87%) patients expired and mortality was highest in pregnant ladies (39.28%). The important neurological sequelae in survivors were psychosis in 15 (5.06%), cerebellar ataxia in 14 (4.72%), hemiplegia in five (1.68%), extrapyramidal rigidity (EPR) in four (1.35%), peripheral neuropathy in three (1.01%), EPR with trismus in one (0.33%) and isolated sixth nerve palsy in one (0.33%) patients and all showed complete recovery in further follow up. CONCLUSION: The important observations of this study were stormy presentation, increased incidence of haemoglobinuria and jaundice, presence of neck rigidity, no prognostic relation to fundus abnormalities and high incidence of cerebellar ataxia and psychosis as neurological sequelae in survivors. Knowledge of self-limiting course of neurological sequelae may be helpful in reducing economic strain of expensive investigations and treatment.

Adult↗
PubMed2001

Persistence of oviposition rhythm in individuals of Drosophila melanogaster reared in an aperiodic environment for several hundred generations.

The oviposition rhythm of individual flies of Drosophila melanogaster from a population maintained in an aperiodic environment (with light, temperature, humidity, and other factors which could provide time cues, kept constant) for several hundred generations was assayed in constant light (LL), in light/dark (LD 12:12 hr) cycle, and in constant darkness (DD). More than 50% of the flies assayed exhibited rhythmicity in oviposition in all three light regimes. The results indicate that the phenomenon of egg laying is rhythmic in individual D. melanogaster females and is controlled by an endogenous time keeping mechanism. The persistence of the oviposition rhythm in a large proportion of individuals in the population after several hundred generations of rearing in a constant environment strengthens the view that possessing biological clocks may confer some intrinsic fitness advantage even to organisms living in aperiodic environments. J. Exp. Zool. 290:541-549, 2001.

Animals↗
PubMed2001

Theory for phase transitions in insulating V2O3.

We show that the recently proposed S = 2 bond model with orbital degrees of freedom for insulating V2O3 not only explains the anomalous magnetic ordering but also other mysteries of the magnetic phase transition. The model contains an additional orbital degree of freedom that exhibits a zero temperature quantum phase transition in the Ising universality class.

Journal Article↗
PubMed2001

Incorporating spatial variation in density enhances the stability of simple population dynamics models.

Simple discrete time models of population growth admit a wide variety of dynamic behaviors, including population cycles and chaos. Yet studies of natural and laboratory populations typically reveal their dynamics to be relatively stable. Many explanations for the apparent rarity of unstable or chaotic behavior in real populations have been developed, including the possible stabilizing roles of migration, refugia, abrupt density-dependence, and genetic variation in sensitivity to density. We develop a theoretical framework for incorporating random spatial variation in density into simple models of population growth, and apply this approach to two commonly used models in ecology: the Ricker and Hassell maps. We show that the incorporation of spatial density variation into both these models has a strong stabilizing influence on their dynamic behavior, and leads to their exhibiting stable point equilibria or stable limit cycles over a relatively much larger range of parameter values. We suggest that one reason why chaotic population dynamics are less common than the simple models indicate is, these models typically neglect the potentially stabilizing role of spatial variation in density.

Animals↗
PubMed2001

MSH-MLH complexes formed at a DNA mismatch are disrupted by the PCNA sliding clamp.

In the yeast Saccharomyces cerevisiae, mismatch repair (MMR) is initiated by the binding of heterodimeric MutS homolog (MSH) complexes to mismatches that include single nucleotide and loop insertion/deletion mispairs. In in vitro experiments, the mismatch binding specificity of the MSH2-MSH6 heterodimer is eliminated if ATP is present. However, addition of the MutL homolog complex MLH1-PMS1 to binding reactions containing MSH2-MSH6, ATP, and mismatched substrate results in the formation of a stable ternary complex. The stability of this complex suggests that it represents an intermediate in MMR that is subsequently acted upon by other MMR factors. In support of this idea, we found that the replication processivity factor proliferating cell nuclear antigen (PCNA), which plays a critical role in MMR at step(s) prior to DNA resynthesis, disrupted preformed ternary complexes. These observations, in conjunction with experiments performed with streptavidin end-blocked mismatch substrates, suggested that PCNA interacts with an MSH-MLH complex formed on DNA mispairs.

Adaptor Proteins, Signal Transducing↗
PubMed2001

MutS recognition: multiple mismatches and sequence context effects.

Escherichia coli MutS is a versatile repair protein that specifically recognizes not only various types of mismatches but also single stranded loops of up to 4 nucleotides in length. Specific binding, followed by the next step of tracking the DNA helix that locates hemi-methylated sites, is regulated by the conformational state of the protein as a function of ATP binding/hydrolysis. Here, we study how various molecular determinants of a heteroduplex regulate mismatch recognition by MutS, the critical first step of mismatch repair. Using classical DNase I footprinting assays, we demonstrate that the hierarchy of MutS binding to various types of mismatches is identical whether the mismatches are present singly or in multiples. Moreover, this unique hierarchy is indifferent both to the differential level of DNA helical flexibility and to the unpaired status of the mismatched bases in a heteroduplex. Surprisingly, multiple mismatches exhibit reduced affinity of binding to MutS, compared to that of a similar single mismatch. Such a reduction in the affinity might be due to sequence context effects, which we established more directly by studying two identical single mismatches in an altered sequence background. A mismatch, upon simply being flipped at the same location, elicits changes in MutS specific contacts, thereby underscoring the importance of sequence context in modulating MutS binding to mismatches.

Adenosine Triphosphatases↗
PubMed2001

K-selection, alpha-selection, effectiveness, and tolerance in competition: density-dependent selection revisited.

In the Drosophila literature, selection for faster development and selection for adapting to high density are often confounded, leading, for example, to the expectation that selection for faster development should also lead to higher competitive ability. At the same time, results from experimental studies on evolution at high density do not agree with many of the predictions from classical density-dependent selection theory. We put together a number of theoretical and empirical results from the literature, and some new experimental results on Drosophila populations successfully subjected to selection for faster development, to argue for a broader interpretation of density-dependent selection. We show that incorporating notions of alpha-selection, and the division of competitive ability into effectiveness and tolerance components, into the concept of density-dependent selection yields a formulation that allows for a better understanding of the empirical results. We also use this broader formulation to predict that selection for faster development in Drosophila should, in fact, lead to the correlated evolution of decreased competitive ability, even though it does lead to the evolution of greater efficiency and higher population growth rates at high density when in monotypic culture.

Animals↗
PubMed2001

Evolution of faster development does not lead to greater fluctuating asymmetry of sternopleural bristle number in Drosophila.

Both strong directional selection and faster development are thought to destabilize development, giving rise to greater fluctuating asymmetry (FA), although there is no strong empirical evidence supporting this assertion. We compared FA in sternopleural bristle number in four populations of Drosophila melanogaster successfully selected for faster development from egg to adult, and in four control populations. The fraction of perfectly symmetric individuals was higher in the selected populations, whereas the FA levels did not differ significantly between selected and control populations, clearly indicating that directional selection for faster development has not led to increased FA in sternopleural bristle number in these populations. This may be because: (i) development time and FA are uncorrelated, (ii) faster development does result in FA, but selection has favoured developmentally stable individuals that can develop fast and still be symmetrical, or (iii) the increased fraction of symmetric individuals in the selected populations is an artifact of reduced body size. Although we cannot discriminate among these explanations, our results suggest that the relationship between development time, FA and fitness may be far more subtle than often thought.

Animals↗
PubMed2001

A case for multiple oscillators controlling different circadian rhythms in Drosophila melanogaster.

A population of the fruit fly Drosophila melanogaster was raised in periodic light/dark (LD) cycles of 12:12 h for about 35 generations. Eclosion, locomotor activity, and oviposition were found to be rhythmic in these flies, when assayed in constant laboratory conditions where the light intensity, temperature, humidity and other factors which could possibly act as time cue for these flies, were kept constant. These rhythms also entrained to a LD cycle of 12:12 h in the laboratory with each of them adopting a different temporal niche. The free-running periods (tau) of the eclosion, locomotor activity and oviposition rhythms were significantly different from each other. The peak of eclosion and the onset of locomotor activity occurred during the light phase of the LD cycle, whereas the peak of oviposition was found to occur during the dark phase of the LD cycle. Based on these results, we conclude that different circadian oscillators control the eclosion, locomotor activity and oviposition rhythms in the fruit fly D. melanogaster.

Journal Article↗
PubMed2001

Development and application of ovine reproductive technologies: an Indian experience.

Sheep play an important role in the Indian economy by providing employment to a large population of marginal and landless farmers. The production from native breeds is relatively low due to their poor reproductive efficiency. Embryo transfer technology can be utilised for faster multiplication of elite animal to increase the genetic gain. A great deal of research is involved to overcome the constraints in the technology, i.e. expensive and complicated nature of the technology and low success rate. In order to avoid surgical involvement, procedures of laparoscope aided embryo collection and transfer have been developed. Although the use of FSH of ovine origin has given more consistent superovulatory response, but it is still too low to get sufficient numbers of progeny from a donor ewe. The progress made in cryopreservation of ram semen has opened the possibility for conservation and utilisation of frozen semen of elite rams in sheep improvement programme. The lambing rate obtained after laparoscope aided intrauterine artificial insemination with frozen semen is encouraging but the impetus is now to develop the non-invasive transcervical insemination technique.

Journal Article↗
PubMed2001

Post-kala-azar dermal leishmaniasis in Nepal.

BACKGROUND: Post-kala-azar dermal leishmaniasis (PKDL) manifests as a skin eruption after healing of visceral leishmaniasis (VL), either spontaneously or as a result of treatment. This study was undertaken to describe the demographic, clinical, and histopathologic features of PKDL in Nepal. METHODS: Demographic, clinical, microbiologic, and histopathologic features and response to treatment were studied in 22 patients with PKDL from April 1998 to March 2000. RESULTS: PKDL accounted for 0.13% of all new dermatologic cases. There were 13 (59.1%) males and nine (40.9%) females. A past history of kala-azar was present in all but one patient. A family history of kala-azar was noted in eight (36.4%) patients. All patients presented with multiple types of lesion, except for two in whom only macular lesions were seen. Oral lesions in the form of nodules and plaques were seen in four patients. Generalized lymphadenopathy was present in five patients. Slit skin smears revealed Leishman-Donovan bodies (LDBs) in nine (40.9%) patients. In macular lesions, there was a sparse infiltrate of plasma cells, lymphocytes, or histiocytes in the upper dermis. There was a dense chronic inflammatory infiltrate comprising plasma cells, lymphocytes, histiocytes, and epithelioid cells in the entire dermis from papules, plaques, or nodules. Giemsa staining of biopsy specimens revealed LDBs in seven (38.9%) patients only. Fine needle aspiration from epitrochlear lymph nodes in two patients demonstrated LDBs. All patients responded well to treatment with minimal side-effects. CONCLUSIONS: This study emphasizes the need to be aware of the possibility of cases of PKDL in endemic regions of leprosy, as the conditions may be difficult to distinguish clinically and histopathologically.

Adolescent↗
PubMed2001

Socket wear in bilateral simultaneous total hip arthroplasty.

A total of 51 patients with bilateral simultaneous Charnley total hip arthroplasties were studied for wear behavior. The mean observation time was 14.7 years. Fourteen hips had been revised during follow-up. The mean wear rate was 0.071 mm/y for left hips and 0.081 mm/y for right hips. There were considerable side differences for individual patients and little agreement between the wear measurements of left and right hips. Linear wear was increased in men, in patients with high body weight. Linear wear after hip arthroplasty is not side related.

Adult↗
PubMed2001

Does the difference in the timing of eclosion of the fruit fly Drosophila melanogaster reflect differences in the circadian organization?

The eclosion rhythm of a laboratory population of Drosophila melanogaster was studied under 12h light, 12h dark (LD 12:12) cycles. Although most of the flies were found to eclose just after "lights on" in LD 12:12, termed within gate (WG) flies, a few flies were found to eclose nearly 10h after peak eclosion, termed outside gate (OG) flies. The circadian parameters of the clocks controlling oviposition rhythms in the WG and the OG flies were estimated to understand the cause of such differences in the timing of eclosion. The distribution of the fraction of individual flies exhibiting single, multiple, and no significant period in the WG flies was significantly different from distribution in the OG flies. Compared to the WG flies, more OG flies were found to exhibit oviposition rhythm with multiple periodicity, whereas more WG flies exhibited an oviposition rhythm with a single significant period. The fraction of flies with arrhythmic oviposition was similar in both the WG and the OG flies. Free-running period tau in constant darkness (DD) and the phase angle difference psi in LD 12:12 for the oviposition rhythm of WG and OG flies were significantly different. These results suggest that the differences in the time of eclosion between the flies eclosing within the gate and outside the gate of eclosion are probably due to differences in the circadian system controlling eclosion, which is reflected by the differences in their oviposition rhythm.

Animals↗
PubMed2001

Correlated responses to selection for faster development and early reproduction in Drosophila: the evolution of larval traits.

Studies on selection for faster development in Drosophila have typically focused on the trade-offs among development time, adult weight, and adult life span. Relatively less attention has been paid to the evolution of preadult life stages and behaviors in response to such selection. We have earlier reported that four laboratory populations of D. melanogaster selected for faster development and early reproduction, relative to control populations, showed considerably reduced preadult development time and survivorship, dry weight at eclosion, and larval growth rates. Here we study the larval phase of these populations in greater detail. We show here that the reduction in development time after about 50 generations of selection is due to reduced duration of the first and third larval instars and the pupal stage, whereas the duration of the second larval instar has not changed. About 90% of the preadult mortality in the selected populations is due to larval mortality. The third instar larvae, pupae, and freshly eclosed adults of the selected populations weigh significantly less than controls, and this difference appears during the third larval instar. Thereafter, percentage weight loss during the pupal stage does not differ between selected and control populations. The minimum amount of time a larva must feed to subsequently complete development is lower in the selected populations, which also exhibit a syndrome of reduced energy expenditure through reduction in larval feeding rate, larval digging and foraging activity, and pupation height. Comparison of these results with those observed earlier in populations selected for adaptation to larval crowding and faster development under a different protocol from ours reveal differences in the evolved traits that suggest that the responses to selection for faster development are greatly affected by the larval density at which selection acts and on details of the selection pressures acting on the timing of reproduction.

Adaptation, Physiological↗
PubMed2001

Noninvasive measurement of acceleration at the knee joint in patients with rheumatoid arthritis and spondyloarthropathy of the knee.

Spondyloarthropathy represents a group of joint diseases with a tendency to reactive new bone formation. Spondyloarthropathy includes Reiter's syndrome, ankylosing spondylitis, and the arthropathy of inflammatory diseases (ulcerative colitis and Crohn's disease). Usually, an extensive investigation is required to distinguish spondyloarthropathy of the knee joint from rheumatoid arthritis. Recently, Reddy et al. (Ann. Biomed. Eng. 23:78-84, 1995) have developed the accelerometry technique to characterize various types of arthritis. The question remains if noninvasive acceleration measurements can be used to distinguish between spondyloarthropathy and rheumatoid arthritis. An ultraminiature accelerometer was placed on the patella, and the subject was asked to rhythmically rotate the knee from 90 flexion to full extension. Results have shown that the mean power of acceleration signal in the range of 100-500 Hz is significantly different (p<0.05) for spondyloarthropathy patients when compared to rheumatoid arthritis patients. The noninvasive accelerometry technique represents a potential tool for characterization of spondyloarthropathy patients.

Acceleration↗