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Biomedical subjects

S Chopra

Publications and source records attributed to S Chopra.

At least 73 records · Page 4Linked to original sources
PubMed2000

Intraocular cilia associated with perforating injury.

PURPOSE: To report a case series of penetrating injury complicated by occurrence of intraocular cilia. METHODS: Retrospective analysis of charts of 11 eyes of 11 patients with penetrating injury and intraocular cilia, presenting between September 1978 and November 1998. Ten eyes underwent surgery for trauma-related problems such as cataract, vitritis, retinal detachment etc., at which time intraocular cilia were removed. One eye did not have surgery and continues to harbour cilia at the posterior perforation site. RESULTS: Metallic wire was responsible for injury in 6 of 11 eyes with intraocular cilia. Five eyes had significant intraocular inflammation. The cilia were located in the anterior segment in 4 eyes; in the posterior segment in 6 eyes and in both in one eye. At the last follow up, 72.7% had 6/18 or better vision. Poor vision in the rest was due to recurrent retinal detachment (2 eyes) and macular scarring (1 eye). CONCLUSION: Intraocular cilia are more commonly associated with injury by a metallic wire. The presentation and management of an injured eye does not seem to be influenced by the presence of cilia in the eye.

Adolescent↗
PubMed1999

Molecular characterization of a mutable pigmentation phenotype and isolation of the first active transposable element from Sorghum bicolor.

Accumulation of red phlobaphene pigments in sorghum grain pericarp is under the control of the Y gene. A mutable allele of Y, designated as y-cs (y-candystripe), produces a variegated pericarp phenotype. Using probes from the maize p1 gene that cross-hybridize with the sorghum Y gene, we isolated the y-cs allele containing a large insertion element. Our results show that the Y gene is a member of the MYB-transcription factor family. The insertion element, named Candystripe1 (Cs1), is present in the second intron of the Y gene and shares features of the CACTA superfamily of transposons. Cs1 is 23,018 bp in size and is bordered by 20-bp terminal inverted repeat sequences. It generated a 3-bp target site duplication upon insertion within the Y gene and excised from y-cs, leaving a 2-bp footprint in two cases analyzed. Reinsertion of the excised copy of Cs1 was identified by Southern hybridization in the genome of each of seven red pericarp revertant lines tested. Cs1 is the first active transposable element isolated from sorghum. Our analysis suggests that Cs1-homologous sequences are present in low copy number in sorghum and other grasses, including sudangrass, maize, rice, teosinte, and sugarcane. The low copy number and high transposition frequency of Cs1 imply that this transposon could prove to be an efficient gene isolation tool in sorghum.

Amino Acid Sequence↗
PubMed1999

Helical CT angiography of transjugular intrahepatic portosystemic shunts.

Shunt dysfunction due to draining hepatic vein and/or stent stenosis is a common long-term complication of transjugular intrahepatic portosystemic shunts (TIPS). Currently, Doppler sonography is the preferred modality for routine screening of TIPS for the detection of these complications. However, this method is time-consuming, highly operator-dependent, and difficult to perform because of the anatomic attributes of the cirrhotic liver. The use of helical CT angiography (HCTA) for imaging TIPS has been recently described. HCTA of TIPS is performed after a rapid i.v. injection of a bolus of low osmolality contrast medium, followed by helical data acquisition of the region of the shunt using thin sections. The data are then reprocessed a overlapping intervals and various reformations are obtained. Preliminary reports show the sensitivity and specificity of the helical CT angiography to be comparable with Doppler sonography.

Angiography↗
PubMed1999

Pregnancy in patients with systemic lupus erythematosus.

We reviewed the obstetrical performance and outcome of 15 pregnancies in patients with systemic lupus erythematosus (SLE) (study group) and compared them with 45 age and parity-matched normal pregnancies (control group). Eleven women (73.8%) were in remission phase and 4 (26.7%) had active disease at the time of conception. The time interval between disease diagnosis and the index pregnancy was 4.2 +/- 2.5 years. Two patients with renal involvement had lupus flare-up during the antenatal period. There was no case of lupus flare-up in the postpartum period. Gestational age at delivery was significantly lower in SLE patients (35.9 +/- 2.5 weeks) compared to the control group (37.4 +/- 2.2 weeks). The incidence of intrauterine growth retardation was significantly higher in the SLE patients (40%). There was no case of neonatal lupus or congenital heart block.

Adult↗
PubMed1999

Diverticulitis versus colon cancer: differentiation with helical CT findings.

PURPOSE: To retrospectively determine the computed tomographic (CT) signs associated with diverticulitis or colon cancer, and to prospectively apply these signs in the differentiation of these diseases. MATERIALS AND METHODS: Fifty-eight CT scans in cases of proved diverticulitis (n = 27) or colon cancer (n = 31) were evaluated retrospectively by radiologists (blinded to the proved diagnosis) for the presence or absence of previously reported CT findings. These findings were correlated with the pathologic or final clinical diagnosis. The retrospective findings were applied in a prospective evaluation with a new set of 72 CT scans. The same five radiologists rendered a diagnosis according to a five-point confidence scale from definitely benign to definitely malignant. Individual and consensus readings were correlated with the final diagnosis. RESULTS: Retrospectively, pericolonic inflammation (P < .01) and segment involvement greater than 10 cm (P < .012) were the most significant findings for diverticulitis; pericolonic lymph nodes (P < .0001) and luminal mass (P < .003) were the most significant findings for colon cancer. Prospectively, an unequivocal diagnosis was made correctly in 16 (40%) of 40 cases of diverticulitis and 21 (66%) of 32 cases of colon cancer. CONCLUSION: When there are no pericolonic lymph nodes adjacent to a segment of colonic wall thickening, with pericolonic inflammatory changes, the most likely diagnosis is diverticulitis. When pericolonic lymph nodes are present, with or without pericolonic edema, the most likely diagnosis is colon cancer.

Colonic Neoplasms↗
PubMed1999

Mesenteric, omental, and retroperitoneal edema in cirrhosis: frequency and spectrum of CT findings.

PURPOSE: To determine the frequency and CT imaging spectrum of mesenteric, omental, and retroperitoneal edema in patients with cirrhosis. MATERIALS AND METHODS: Eighty patients were identified with liver cirrhosis and no other cause of edema. Five radiologists jointly reviewed the abdominal CT scans of these patients to assess, by majority decision, the presence, severity, distribution, and configuration of mesenteric edema and the presence of omental and retroperitoneal edema. Subcutaneous edema, ascites, pleural effusion, splenomegaly, varices, portal venous thrombosis, and serum albumin levels were also documented. RESULTS: Mesenteric edema was present in 69 (86%) patients. Mesenteric edema occurred alone in 26 (38%) and with omental or retroperitoneal edema in 40 (58%) of the 69 patients with edema. No patient had omental or retroperitoneal edema alone. Mesenteric edema was mild in 51 (74%) and moderate to severe in 18 (26%), patchy in 47 (68%) and diffuse in 22 (32%), purely infiltrative in 60 (87%) and infiltrative with superimposed masslike nodules in nine (13%) patients. These parameters had significant associations among themselves and with ascites, pleural effusions, subcutaneous edema, and low mean serum albumin levels but not with splenomegaly or varices. CONCLUSION: Mesenteric, omental, and retroperitoneal edema occur commonly in patients with cirrhosis. The appearance of mesenteric edema varies from a mild infiltrative haze to a severe masslike sheath that engulfs the mesenteric vessels.

Adult↗
PubMed1998

Induction of spermidine/spermine N1-acetyltransferase in human cancer cells in response to increased production of reactive oxygen species.

Reactive oxygen species (ROS) are involved in a number of disease states where they are believed to be responsible for cellular damage. In this study we examined the effect of ROS generation on polyamine catabolism. Treatment of human breast cancer cells with either H2O2 or hyperoxia increased the activity of spermidine/spermine N1-acetyltransferase (SSAT). These increases occurred before any significant signs of cellular injury. Agents known to decrease the production of reactive oxygen species such as dimethylthiourea and o-phenanthroline prevented the increase in SSAT activity indicating ROS involvement in the induction process. These results suggest that induction of SSAT may be a protective response to oxidative stress in mammalian cells facilitating removal of polyamines from the cell to prevent their toxic accumulation.

Acetyltransferases↗
PubMed1998

A maize Myb homolog is encoded by a multicopy gene complex.

The maize P gene encodes a Myb-homologous transcriptional regulator of flavonoid pigmentation in floral organs, and different P gene alleles condition precise tissue- and organ-specific pigmentation patterns. To determine the molecular basis for allele-specific expression patterns, we have isolated and compared two natural alleles of the P gene which differ in expression, structure and copy number. The P-rr allele is associated with pigmentation of most floral tissues and contains a single copy of the P gene. In contrast, the P-wr allele restricts pigmentation to a subset of floral tissues, and is composed of six gene copies arranged in a tandem head-to-tail array. Each of the six repeats contains a single P gene, including regulatory and coding sequences. Despite the six-fold tandem repetition of P-wr gene copies, P-wr mRNA levels in kernel pericarp are much reduced compared to mRNA levels from the single-copy P-rr gene. Moreover, the P-wr multicopy complex is hypermethylated relative to P-rr. Thus, maize P gene alleles may represent a natural system for studying the effects of methylation and gene copy number on tissue-specific gene expression. We discuss the possibility that somatic pairing of repeated gene copies may be involved in regulating gene expression.

Alleles↗
PubMed1998

Expression of nerve growth factor receptors in cutaneous inflammation.

Evidence indicates that the neurotrophin nerve growth factor (NGF) is a mediator of cutaneous inflammatory responses. Cellular responses to NGF are facilitated by two receptors called trk A and p75 neurotrophin receptor (p75NTR). In the current study we have investigated the expression of these receptors in lesional and non-lesional skin from patients with plaque psoriasis and in normal skin exposed to three times the minimal erythema dose of ultraviolet (UV) B radiation. Trk A immunostaining was confined to the basal keratinocytes in normal skin. There was a significant reduction in trk A immunostaining in both non-lesional and lesional psoriatic skin compared with control skin. In UVB-irradiated normal skin, there was a significant reduction in trk A immunostaining at 4 h after irradiation, which was still evident at 48 h. In normal skin, p75NTR immunopositive fine nerve fibres were present throughout the dermis and occasionally seen in the epidermis. Thick nerve fibres were evident in the deep dermis and in the middle region of the dermis. p75NTR immunopositive basal keratinocytes were occasionally seen. There was a statistically significant loss of p75NTR immunopositive fine nerve fibres in the epidermis of lesional psoriatic skin and a statistically significant loss of p75NTR immunopositive fine nerve fibres in the dermis in both non-lesional and lesional psoriatic skin. p75NTR immunopositive thick nerve fibres were reduced in lesional psoriatic skin compared with normal skin. UVB irradiation of normal skin led to a statistically significant decrease in the p75NTR immunopositive fine nerve fibres in the epidermis at 48 h after irradiation. There was no significant reduction in the dermal p75NTR immunoreactivity. These results demonstrated that expression of both NGF receptors is decreased following an acute inflammatory stimulus and also in association with a chronic inflammatory dermatosis.

Adult↗
PubMed1998

Cutaneous responses to endothelin-1 and histamine in patients with vibration white finger.

Vibration white finger (VWF) is the episodic blanching of the fingers that occurs in response to cold in those who work with hand-held vibrating tools. Clinically the condition differs from primary Raynaud's phenomenon as persistent pain and paresthesia are common in the hands and arms and occur independently of the "white attacks." We have previously reported a decrease in protein gene product 9.5 and calcitonin gene-related peptide-immunoreactive nerve fibers in the digital skin of individuals with VWF. In this study, we have sought to determine whether this deficit of immunoreactive sensory-motor nerves has a functional counterpart in vivo. Histamine produces a rapid wheal and flare response following intradermal injection, whereas endothelin-1 (ET-1) produces a central area of pallor with a surrounding neurogenic flare. In contrast, calcitonin gene-related peptide produces a non-neurogenic erythema. In this study, histamine and ET-1 were injected into the dorsum of the middle phalanx and the local neurovascular response was assessed by measuring the area of the visible flare or pallor. Basal finger blood flow was also measured by laser Doppler flowmetry in each of the digits prior to intradermal injection. The experiments were performed at 21 degrees C and 4 degrees C. Patients with VWF and asymptomatic vibration-exposed workers had significantly lower resting skin blood flow at both 21 degrees C and 4 degrees C than heavy manual workers with no vibration exposure. The size of the histamine- and ET-1-induced flares at both 21 degrees C and 4 degrees C was significantly smaller in patients with VWF when compared with the asymptomatic vibration-exposed workers and heavy manual workers. The size of the ET-1-induced pallor was smaller in patients with VWF when compared with the heavy manual workers at both 21 degrees C and 4 degrees C. In contrast, the area of erythema induced by intradermal injection of calcitonin gene-related peptide at both 21 degrees C and 4 degrees C was of a similar size in patients with VWF and in heavy manual workers. These results indicate that the neuroneal deficit identified by immunohistochemistry in the digital skin of patients with VWF has a functional counterpart in vivo and is evident as a reduced ability to propagate an axon-reflex vasodilator response when challenged with histamine and ET-1. Furthermore, these results enable patients with VWF to be differentiated from both asymptomatic vibration-exposed workers, in whom the histamine- and ET-1-induced flares are normal, and those with primary Raynaud's disease, in whom the ET-1 flare is reduced and the histamine-induced flare is normal.

Adult↗
PubMed1998

Biliary sludge formation during enteral nutrition: prevalence and natural history.

BACKGROUND: Total parenteral nutrition is an etiologic factor in the formation of biliary sludge. We studied whether enteral nutrition is also a risk factor for sludge. METHODS: Fifty patients with a needle catheter jejunostomy (NCJ) placed during a major abdominal operation underwent preoperative and weekly postoperative ultrasonography until NCJ feedings were discontinued (1 to 6 weeks). RESULTS: All patients were men. The mean age was 63.2 +/- 1.6 years. Fourteen asymptomatic patients (28.0%) had biliary sludge within 2 weeks of beginning enteral feedings through a NCJ. Complete ultrasonographic resolution of sludge was observed in 13 of the 14 positive patients within 1 to 2 weeks of resuming an oral diet. One patient was lost to follow-up after 14 week; a positive sonogram had persisted but the patient remained asymptomatic. During the period of observation, no other patient had signs of biliary tract disease. CONCLUSIONS: (1) Biliary sludge may form in some patients during enteral feeding with NCJ. (2) Sludge is cleared by the gallbladder once an oral diet is resumed. (3) There appears to be little risk of complications during postoperative enteral feeding.

Bile↗
PubMed1998

Abnormal radionuclide uptake in pseudomyxoma peritonei.

A case of pseudomyxoma peritonei with increased radionuclide uptake in the abdomen is described. The uptake of the radionuclide was confined to the omentum as confirmed by the CT study of the abdomen and pelvis. The mechanism of uptake and differential diagnosis are discussed.

Abdomen↗
PubMed1998

AST/ALT ratio predicts cirrhosis in patients with chronic hepatitis C virus infection.

OBJECTIVE: A liver biopsy is necessary to grade and stage chronic hepatitis C virus (HCV) infection. In a previous study of patients with nonalcoholic liver disease, an aspartate aminotransferase (AST) to alanine aminotransferase (ALT) ratio >1 suggested cirrhosis. We sought to examine the value of the AST/ALT ratio in distinguishing cirrhotic patients with chronic HCV infection from noncirrhotic patients and to correlate the ratio with the grade and stage of hepatitis and other biochemical indices. METHODS: We retrospectively studied 139 patients with chronic HCV infection. Routine biochemical indices were determined, and the histological grade of necroinflammatory activity and the stage of fibrosis of the liver biopsy specimens were scored. RESULTS: The mean AST/ALT ratio in the cirrhotic patients (n = 47) was higher than in the noncirrhotic patients (n = 92) (1.06 +/- 0.06 vs 0.60 +/- 0.09; p < 0.001). A ratio > or =1 had 100% specificity and positive predictive value in distinguishing cirrhotic from noncirrhotic patients, with a 53.2% sensitivity and 80.7% negative predictive value. The ratio correlated positively with the stage of fibrosis but not with the grade of activity or other biochemical indices. Of the cirrhotic patients, 17% had no clinical or biochemical features suggestive of chronic liver disease except for an AST/ALT ratio > or =1. CONCLUSION: The AST/ALT ratio is a dependable marker of fibrosis stage and cirrhosis in patients with chronic HCV infection.

Adult↗
PubMed1998

Risk factors associated with chronic hepatitis C virus infection: limited frequency of an unidentified source of transmission.

OBJECTIVES: Risk factors have been studied in patients with acute non-A, non-B hepatitis, and approximately 40-50% have no known risk factor for viral acquisition. A significant undefined source of viral transmission has been suggested. We sought to clearly delineate the risk factors in a population of patients with documented chronic hepatitis C virus (HCV) infection to assess the magnitude of HCV transmission without known risk factors. METHODS: Risk factor profiles were carefully assessed in 301 consecutive patients with chronic HCV infection. Patients were classified by gender and age. Overall risk factor distributions were calculated and comparisons were made between groups to detect differences in mode of HCV acquisition. RESULTS: One hundred ninety-six men and 105 women were studied; 223 were age < or = 45 yr and 78 were > 45 yr. Overall, 25% of patients had a history of transfusion and 49% had a history of intravenous drug use (i.v.DU). Only 12% had no history of risk factor exposure. Men were more likely to have a history of i.v.DU and less likely to have a history of blood transfusion or sexual exposure/household contact. Younger patients were more likely to have a history of i.v.DU and older patients were more likely to have a history of blood transfusion and to deny all risk factor exposure. CONCLUSIONS: A careful history delineated a potential risk factor for HCV acquisition in 88% of patients with chronic HCV infection. Men and younger patients had different risk factor profiles than women and older patients, respectively. It is likely that an important unknown mode of HCV transmission occurs in a significant minority of patients.

Adult↗
PubMed1997

Nonalcoholic steatohepatitis.

OBJECTIVE: To determine the clinical relevance of nonalcoholic steatohepatitis (NASH) and to review the available literature on the epidemiology, clinical features, histology, pathogenesis, clinical course, and management of this condition. DATA SOURCES: Pertinent articles in English identified through a MEDLINE search (1966 to the present) and the bibliographies of relevant articles. STUDY SELECTION: All studies, including case reports, evaluating the salient features and clinical profile of NASH. DATA EXTRACTION: Data were selected from all articles that fit the study selection criteria. DATA SYNTHESIS: Nonalcoholic steatohepatitis is a distinct clinical entity characterized by elevated plasma liver enzyme levels and liver biopsy findings that are identical to those seen in alcoholic hepatitis; patients with NASH, however, do not consume alcohol in quantities known to cause liver injury. Patients with NASH are typically obese, middle-aged women with asymptomatic hepatomegaly who are diabetic or hyperlipidemic and present with an unrelated medical problem. Analysis of liver biopsy specimens is the cornerstone of diagnosis; hepatic morphologic findings range from mild fatty degeneration and inflammation to cell degeneration, fibrosis, and cirrhosis with or without the presence of Mallory hyaline bodies. Elevated levels of free fatty acids in the liver are thought to be responsible for the development of steatohepatitis. Although NASH is most often a benign disease with an indolent course, patients with this condition occasionally develop cirrhosis, portal hypertension, and hepatic failure. In some cases, NASH may be reversed with weight reduction. CONCLUSION: Nonalcoholic steatohepatitis is an important differential diagnosis for asymptomatic patients with chronically elevated plasma liver enzyme levels, especially if obesity, diabetes, or hyperlipidemia are present. Analysis of liver biopsy specimens is necessary for diagnosis and must be done in all patients with unexplained abnormal liver function and negative results on a noninvasive workup. Prognosis is good in most patients. The precise role of weight reduction and ursodeoxycholic acid therapy in the favorable alteration of the natural history of this disorder needs to be addressed in large, well-controlled studies.

Female↗