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Biomedical subjects

B Kumar

Publications and source records attributed to B Kumar.

At least 55 records · Page 3Linked to original sources
PubMed2003

Defects in cAMP-pathway may initiate carcinogenesis in dividing nerve cells: a review.

The mechanisms of carcinogenesis in nervous tissues are not well understood. It is now established that adenosine 3,',5'-cyclic monophosphate (cAMP)-pathway plays a crucial role in initiating differentiation in transformed and embryonic cells of neuronal and glial origin. Therefore, we propose that defects in the cAMP-pathway may initiate the first phase of carcinogenesis (immortalization). Subsequent genetic abnormalities in oncogenes, anti-oncogenes or other cellular genes individually or in combination may lead to transformation (cancer phenotype). This hypothesis is derived from the fact that an elevation of the cAMP level in murine NB cells induces terminal differentiation in many of these cells in spite of the fact that they are highly aneuploid. Additional changes in cAMP-regulated genes responsible for initiating differentiation may make these cells resistant to cAMP or may make the cAMP-effect on differentiation reversible. Indeed, cAMP-resistant cells exist in NB cell populations, and the cAMP-effect on differentiation is reversible in glioma cells. Identification of genes that initiate, promote and maintain terminal differentiation and those which prevent differentiation following elevation of cAMP in NB cells may increase our understanding of the mechanisms of carcinogenesis. This review illustrates the following: (a) historical background leading to the discovery of cAMP as an inducer of differentiation in nerve cells; (b) identification of potential sites in cAMP-pathway that may play a crucial role in initiating the first phase of carcinogenesis (immortalization) and potential gene targets in immortalized cells whose alterations may cause neoplastic transformation of nerve cells. It is interesting to note that the cAMP pathway remains responsive to an elevated cAMP level in inducing differentiation in NB cells in spite of chromosomal anomalies and genetic changes associated with the maintenance of a cancer phenotype.

Adenylyl Cyclases↗
PubMed2003

Eumelanin and phaeomelanin contents of depigmented and repigmented skin in vitiligo patients.

BACKGROUND: There are two chemically distinct types of melanin: the red-yellow phaeomelanin and the brown-black eumelanin. Both types of melanin have been detected in human hair, epidermis and cultured melanocytes. OBJECTIVES: In a preliminary study, to quantify levels of both eumelanin and phaeomelanin in depigmented as well as repigmented patches of vitiligo following psoralen plus ultraviolet A (PUVA) therapy. METHODS: We enrolled five patients with vitiligo for this study. We took biopsies from depigmented as well as repigmented lesions after PUVA therapy. The eumelanin and phaeomelanin contents of the skin biopsies were quantified by high-performance liquid chromatography. RESULTS: The mean concentrations in depigmented lesions were 229.4 ng per piece for phaeomelanin and 572 ng per piece for eumelanin (mean phaeomelanin/eumelanin ratio 0.36). In repigmented lesions, the mean concentration of phaeomelanin was 74.8 ng per piece and that of eumelanin was 1657.6 ng per piece (mean phaeomelanin/eumelanin ratio 0.049). CONCLUSIONS: Depigmented lesions showed both types of melanin, and contained a substantial amount of phaeomelanin, whereas repigmented lesions after PUVA showed predominantly eumelanin. We detected melanin in depigmented lesions of vitiligo of 5 years duration, suggesting that some residual melanocytes are still active in depigmented lesions.

Adult↗
PubMed2003

Chronic macrocheilia: a clinico-pathological study of 28 patients.

Chronic macrocheilia has a multifactorial aetiology and is often a diagnostic and therapeutic challenge. Epidemiological information on this condition is scarce, most of the data reported relating only to granulomatous cheilitis. We have performed a detailed clinico-pathological analysis of all patients with chronic macrocheilia presenting to us during the last 6.5 years. Of the 28 patients identified, 13 (46.4%) had granulomatous cheilitis (GC), six (21.4%) had tuberculosis of the lip, three (10.7%) had leprous macrocheilia, two (7.1%) had multiple endocrine neoplasia type IIb, and one each had Ascher's syndrome and non-Hodgkin's lymphoma. Two patients were diagnosed as 'nonspecific cheilitis'. Histopathological differentiation between tuberculosis and GC was often not possible; but PCR for Mycobacterium tuberculosis was positive in all patients with tuberculosis and negative in four patients with GC in whom M. tuberculosis was sought. In spite of detailed clinical examination and investigations, a therapeutic trial was required to confirm the diagnosis in five (17.9%) patients. We have reviewed the available literature on this subject, and to our knowledge this study is the first of its kind. More such studies from other centres will help physicians to make an accurate aetiological diagnosis and treat this uncommon but disfiguring condition with confidence.

Adolescent↗
PubMed2003

Evaluation of emergency dermatological consultations in a tertiary care centre in North India.

INTRODUCTION: The nature of dermatological consultations in an emergency setting has not been studied in detail. AIM: To evaluate the reasons and the nature of emergency dermatological consultations at a tertiary care centre in India. MATERIAL AND METHODS: One hundred consecutive emergency calls received over a period of four months from the emergency outpatient department were included in the analysis. The details of all the patients along with their clinical diagnosis were recorded in a proforma. In order to evaluate the reasons for emergency calls they were divided into four categories; Category I comprised of primarily dermatological disorders without any systemic involvement, Category II included III consisted of primarily systemic disorders with related cutaneous lesions and in Category IV systemic diseases with unrelated cutaneous findings were included. RESULTS: Out of 100 patients, 63 were males and 37 were females. The number of calls in categories I-IV was 57, 9, 7 and 27 respectively. Infections (32) constituted the most common dermatological presentations, followed by drug reactions (27). Only 21 were true dermatological emergencies. CONCLUSION: Diagnosis and management of common skin diseases should be stressed during the training of physicians in emergency medicine.

Child↗
PubMed2003

Lymphangioma circumscriptum of the penis mimicking venereal lesions.

Lymphangioma circumscriptum (LC) involving the penis is rare. We report two patients with penile LC. The lesions developed in early infancy in one patient, and during puberty in the other. The lesions resembled molluscum contagiosum in one and genital warts in the other. The first patient was previously treated with a diagnosis of venereal disease. A literature search found only 4 LC patients with penile lesions reported in the English literature. These cases are presented for their rarity, and to increase diagnostic vigilance and desirability of non-intervention.

Adult↗
PubMed2002

Mucocutaneous adverse effects of hydroxyurea: a prospective study of 30 psoriasis patients.

Hydroxyurea is an anti-tumour agent most commonly used to treat chronic myeloproliferative disorders in doses up to 4 g per day. Dermatological adverse effects reported so far have been observed predominantly in these patients. As we are treating selected psoriasis patients with low dose hydroxyurea we attempted to define the spectrum and chronology of dermatological adverse effects in this group of patients prospectively. Of the 29 evaluable patients, 19 (65.5%) developed a mucocutaneous adverse reaction after a mean duration of 6.4 weeks of treatment. Pigmentation of nails, skin or mucosa was the most common observation and was seen in 17 (58.6%) patients. Other less common findings were xerosis, diffuse alopecia, oedema of the legs, oral ulcers and actinic psoriasis. Adverse effects subsided in 11 (57.9%) patients during a mean follow up of 18 weeks. Three hitherto unreported side-effects - scleral pigmentation, acquired ichthyosis and pigmentation of lunula of the nails - were noted. This first study of dermatological adverse effects of hydroxyurea therapy on Asian psoriatic patients reveals several new findings. Pigmentation of skin, nails and mucosa appears to be very common and occurs early. Serious dermatological side-effects probably do not occur with low dose (up to 1.5 g per day) hydroxyurea in patients with psoriasis.

Adult↗
PubMed2002

Pros and cons of antioxidant use during radiation therapy.

Radiation therapy is one of the major treatment modalities in the management of human cancer. While impressive progress like more accurate dosimetry and more precise methods of radiation targeting to tumor tissue has been made, the value of radiation therapy in tumor control may have reached a plateau. At present, two opposing hypotheses regarding the use of antioxidants during radiation therapy have been proposed. One hypothesis states that supplementation with high doses of multiple micronutrients including high dose dietary antioxidants (vitamins C and E, and carotenoids) may improve the efficacy of radiation therapy by increasing tumor response and decreasing some of its toxicity on normal cells. The other hypothesis suggests that antioxidants (dietary or endogenously made) should not be used during radiation therapy, because they would protect cancer cells against radiation damage. Each of these hypotheses is based on different conceptual frameworks that are derived from results obtained from specific experimental designs, and thus, each may be correct within its parameters. The question arises whether any of these concepts and experimental designs can be used during radiation therapy to improve the management of human cancer by this modality. This review has analyzed published data that are used in support of each hypothesis, and has revealed that the current controversies can be resolved, if the results obtained from one experimental design are not extrapolated to the other. This review has also discussed the scientific rationale for a micronutrient protocol that includes high doses of dietary antioxidants (vitamin C, vitamin E succinate and natural beta-carotene) which can be used adjunctively with radiation therapy.

Animals↗
PubMed2002

Lack of effect of dimethylsulphoxide in cutaneous amyloidosis.

OBJECTIVE: To evaluate dimethylsulphoxide (DMSO) as a topical therapeutic agent for the treatment of two major variants of primary, localized, cutaneous amyloidosis -- macular amyloidosis (MA) and papular/lichen amyloidosis (LA) -- using a monocentric, open, prospective trial. METHODS: A total of 25 patients with histopathologically proven cutaneous amyloidosis - MA, LA and BA (biphasic amyloidosis) (13 MA, seven LA, five BA) were requested to undertake a once daily application of either 50% or 100% DMSO for 12 weeks. Progress was regularly assessed with a scoring system for pruritus, pigmentation and papules. RESULTS: In 17 (68%) cases, the scores for pruritus decreased but never completely disappeared in any of the patients. Lightening of the pigmentation was noted in only six (24%) cases and the scores for the papules were decreased in only two out of 12 (16.6%) patients. Post-treatment skin biopsies did not reveal a reduction/disappearance of the amyloid deposits. In the follow-up period, the relapse rate was 100%. CONCLUSION: DMSO does not have an anti-pruritic effect or amyloid-dissolving properties. As the results are partial and transient, it is concluded that DMSO is not a satisfactory treatment for cutaneous amyloidosis.

Adolescent↗
PubMed2002

Fabric-staining properties and washability of a novel liposomal dithranol formulation.

AIM: To test the staining potential of a novel liposomal dithranol gel on different types of fabrics and compare it with the only commercially available dithranol preparation in India, Derobin. METHODS: Pure cotton, pure polyester and four blends of the two fabrics were tested for staining and washability. RESULTS: Both products showed the least staining and spreading on pure cotton with progressively worse stains as the proportion of polyester in the fabric increased. When compared with each other the liposomal dithranol gel showed markedly lighter staining than Derobin on all fabrics. It also washed off completely with water whereas the Derobin stains could not be washed off, even with detergent. CONCLUSION: The liposomal gel due to its superior staining properties may potentially increase the acceptability of dithranol amongst psoriasis patients.

Administration, Topical↗
PubMed2002

Pesticide (acephate) removal by GAC: a case study.

Pesticides are persistent pollutants which need utmost attention in agricultural pollution. They usually accumulate in the food chain, and hence are hazardous in nature. The present study reports the performance of granular activated carbon (GAC) in the removal of acephate contained in the effluent of a nearby pesticide manufacturing industry. In the batch study, the optimum dose of GAC was found to be 85 gm/litre for almost 100% removal of acephate from its initial concentration of 2.9 mg/litre which was found in the industrial effluent under treatment. The adsorption kinetics were represented closely by Langmuir isotherm. The equilibrium time was found as 80 minutes. The adsorptive capacity of GAC for acephate (pesticide) was of the order of 0.04614 mg/gm. A column system was devised and designed based on bed depth-service time (BDST) approach with the experimental value of 'a' and 'b' as 6.125 and 47.75 respectively.

Adsorption↗
PubMed2001

Transport tensors in perfectly aligned low-density fluids: self-diffusion and thermal conductivity.

The modified Taxman equation for the kinetic theory of low-density fluids composed of rigid aspherical molecules possessing internal degrees of freedom is generalized to obtain the transport tensors in a fluid of aligned molecules. The theory takes care of the shape of the particles exactly but the solution has been obtained only for the case of perfectly aligned hard spheroids within the framework of the first Sonine polynomial approximation. The expressions for the thermal-conductivity components have been obtained for the first time whereas the self-diffusion components obtained here turn out to be exactly the same as those derived by Kumar and Masters [Mol. Phys. 81, 491 (1994)] through the solution of the Lorentz-Boltzmann equation. All our expressions yield correct results in the hard-sphere limit.

Journal Article↗
PubMed2001

Effects of altered cyclophilin A expression on growth and differentiation of human and mouse neuronal cells.

1. Cyclophilin A (CyP-A), a soluble cytoplasmic immunophilin, is known for its involvement in T cell differentiation and proliferation. Although CyP-A has a pivotal role in the immune response, it is most highly concentrated in brain, where its functions are largely unknown. 2. We reported previously that a murine neuroblastoma (NB-P2) cell line can partially differentiate into neurons when treated with cyclosporin A (CyS-A), implicating a role for CyP-A in neuronal differentiation (Hovland et al. [1999]. Neurochem. Int. 3:229-235). 3. The role of CyP-A in regulating neuronal growth and differentiation is not well defined. To investigate this, we first tested the utility of retroviral-mediated gene transfer and expression in human embryonic brain (HEB) and NB-P2 cells. Second, we examined the effects of retroviral-mediated overexpression or antisense-mediated reduction of CyP-A in HEB and NB-P2 cells. 4. Our data show that retroviral vectors are efficient for stable gene transfer and expression in both cell lines. Moreover, neither overexpression nor reduction of CyP-A expression in NB-P2 cells altered the growth rate or induced differentiation. More importantly, the up-or down-regulation of CyP-A expression did not affect the magnitude of cAMP-induced NB-P2 differentiation. However, overexpression of CyP-A increased the growth rate of HEB cells. 5. In summary, the utility of retroviral vectors for stable gene expression in human embryonic brain and murine neuroblastoma cells was shown. Furthermore, a novel role for CyP-A in augmenting the proliferation of human embryonic brain cells was demonstrated in vitro.

Animals↗