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Biomedical subjects

Deepak Narayan

Publications and source records attributed to Deepak Narayan.

16 recordsLinked to original sources
PubMed2006

Rab33A: characterization, expression, and suppression by epigenetic modification.

Rab33A, a member of the small GTPase superfamily, is an X-linked gene that is expressed in brain, lymphocytes, and normal melanocytes, but is downregulated in melanoma cells. We demonstrate that in normal melanocytes Rab33A colocalizes with melanosomal proteins and that a constitutively active GTPase mutant suppresses their transport to the melanosomes. In the brain, Rab33A is present throughout the cortex, as well as in the hippocampal CA fields. A survey of melanocytic lesions demonstrated that aberrant downregulation of Rab33A is an early event that is already prevalent in melanocytes of giant congenital nevi. Analyses of bisulfite-modified DNA revealed that Rab33A is regulated by DNA methylation of a specific promoter region proximal to the transcription initiation site, and that suppression of Rab33A in melanoma cells recapitulates normal processes that control silencing of X-linked genes, but not tissue specific gene expression. This information is important for understanding carcinogenesis as well as other aberrant processes because Rab33A may have an important role in disorders involving X-chromosome-linked genes associated with vesicular transport.

Amino Acid Sequence↗
PubMed2006

Alloderm stabilization of zygomatic arch fractures.

Zygomatic arch fractures, particularly when comminuted, are unstable fractures that may lose their reduction after operative manipulation. This case study describes the use of Alloderm as a postoperative stabilizing agent in two patients.

Biocompatible Materials↗
PubMed2006

Managing extracavitary prosthetic vascular graft infections: a pathway to success.

Prosthetic vascular graft infections portend grave consequences if not treated expediently. Despite the low incidence of infection, the potential for limb loss or death greatly magnifies this complication. The surgical management of prosthetic graft infections has evolved over the last 2 decades. With the myriad therapeutic options now available, an algorithm is necessary to provide the optimal surgical treatment of Samson groups 1 through 5 extracavitary infected vascular prostheses. An extensive review of the literature was undertaken to evaluate the most effective management schemes. The authors found that 3 factors--Samson classification, bacteriology, and patient vascular anatomy--are vital to the surgical strategy. These 3 criteria were examined, and an algorithm was developed based on successful clinical and experimental results. This review provides a step-by-step rationale for the surgical management of extracavitary prosthetic graft infections according to the most successful reported outcomes.

Algorithms↗
PubMed2006

Giant nevi: a review.

Congenital nevi are benign neoplasms that are present at birth and composed of nevomelanocytes. Approximately 1-3% of all newborns have congenital pigmented nevi, and the number of nevi increases with age, peaking by late adolescence to 20-40 nevi in an individual. Giant congenital nevi are often defined as nevi that are greater than 20 cm in diameter in an adult, or nevi that occupy 2% or more of the body surface area. Histologically, nevi are transformed melanocytes, which are normally highly dendritic cells interspersed among basal keratinocytes. The genetic basis of these lesions is not known. Findings of a culture of melanocytes from such a lesion from a showed chromosome rearrangements involving 1p,12q, and 19p. The giant nevi might be associated to several diseases: neurocutaneous melanosis, diffuse lipomatosis, structural brain malformations, hypertrophy of skull bones, limb atrophy, skeletal asymmetry involving both soft tissue hyper-and hypoplasia, von Recklinghausen's disease and vitiligo. The risk of malignant change in giant nevi is probably the most contentious issue in its management. The consensus is that lesions are pre-malignant, but the purported incidence of malignancy varies wildly from 0-42%. Surgical excision remains the mainstay of treatment for large congenital melanocytic nevi, and most giant nevi are managed by staged excision and resurfacing with skin grafts or tissue expanders and flaps.

Humans↗
PubMed2005

Long-term effects of hormone therapy on skin rigidity and wrinkles.

OBJECTIVE: To evaluate the effects of long-term hormone therapy (HT) on skin rigidity and wrinkling. DESIGN: Single blinded cross-sectional analysis. SETTING: Academic medical center. PATIENT(S): Sixty-five long-term HT users who underwent menopause at least 5 years before evaluation and who have either consistently used HT or have never used HT. INTERVENTION(S): Visual assessment of severity of wrinkles at 11 facial locations using the Lemperle scale by a plastic surgeon blinded to HT use. Measurement of skin rigidity at the cheek and forehead with a durometer. MAIN OUTCOME MEASURE(S): Lemperle wrinkle score and skin rigidity. RESULT(S): Twenty women met inclusion criteria. Eleven women who had not used HT were compared to nine long-term HT users. Demographics including age, race, sun exposure, sunscreen use, tobacco use, and skin type were similar. Rigidity was significantly decreased in HT users compared to nonusers at both the cheek (1.1 vs. 2.7) and forehead (20 vs. 29). Average wrinkle scores were lower in hormone users than in nonhormone users (1.5 vs. 2.2). CONCLUSION(S): Long-term postmenopausal HT users have more elastic skin and less severe wrinkling than women who never used HT, suggesting that hormone therapy may have cosmetic benefits.

Cross-Sectional Studies↗
PubMed2005

Head and neck angiosarcomas.

Angiosarcoma of the head and neck is a rare and lethal neoplasm. Data from the Connecticut Tumor Registry was analyzed for all head and neck angiosarcomas between 1980 and 2001. The authors also present the first reported case of familial angiosarcoma of the head and neck region. The 1-year mortality was 48% for all patients with angiosarcomas (38% for males, 69% for females). The 5-year survival was 28% for all patients (38% for males, 15% for females). The combination of surgery and radiotherapy resulted in improved survival compared with either treatment alone.

Adult↗
PubMed2005

Necrobiosis lipoidica resulting in squamous cell carcinoma.

Necrobiosis lipoidica is a chronic degenerative disease of dermal connective tissue, of unknown etiology, which occurs mostly in diabetic patients. It may occasionally be complicated by squamous cell carcinoma. Since this combination is rare, a high index of suspicion is necessary to establish the diagnosis. We present a case and a review of the literature.

Adult↗
PubMed2004

Elihu Yale and the medicine he promoted: the government general hospital and Madras Medical College, India.

Much has been written about the philanthropist Elihu Yale and his life in the Americas and England, where he spent his beginnings and end. Less publicized is his life in India, where he spent the majority of his adult life and where he raised his family. A major contribution of Elihu Yale to medicine in India was his promotion of a local hospital in the major Indian trading port city of Madras. This essay briefly describes the history of that hospital and the medical college that grew out of it.

Colonialism↗
PubMed2003

Microarray gene analysis and expression profiles of Dupuytren's contracture.

Dupuytren's disease, although not altogether uncommon, has eluded scientists who have sought to explain the cause of this palmar fibroproliferative disorder. It can lead to severe limitations of hand function if left untreated. This study is the first broad genetic survey using microarray technology to find gene products that are overexpressed or underexpressed in diseased tissues. The authors found 23 genes with levels that differ consistently from control levels. Nine were selected for further verification using reverse transcription-polymerase chain reaction. These genes hold potential promise in explaining some of the demographic trends seen with disease, such as correlation with alcoholism and the striking predisposition for the male gender.

Aged↗
PubMed2002

Cosmetic concerns in pediatric craniofacial surgery.

This article highlights the technical details of the authors' techniques in the surgical management of craniosynostosis. The role of orthotic devices vis-a vis positional plagiocephaly and postsurgical molding is discussed. A method of avoiding temporal hollowing in cranioplasty is presented.

Child↗
PubMed2002

Merkel cell carcinoma: five case reports using sentinel lymph node biopsy and a review of 110 new cases.

Merkel cell carcinoma is an uncommon cutaneous tumor that is considered locally aggressive and often spreads regionally through lymphatic channels. Evaluation of surgical treatment methods has been hampered by the low incidence of this tumor. Current standards of treatment include wide surgical excision and regional lymphadenectomy if clinically suspicious nodes are present. However, the development and increasing use of sentinel node imaging and biopsy have expanded the diagnostic options. This article presents information on 110 Merkel cell carcinomas treated in Connecticut between 1990 and 1997. Statistics on gender, age, disease location, treatment, and mortality are reviewed. Using the census data for Connecticut, the annual incidence for this disease was calculated to be 0.42 cases per 100,000 people. A series of five cases treated with wide excision and sentinel lymph node biopsy is also presented.

Adult↗