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Biomedical subjects

S Gautam

Publications and source records attributed to S Gautam.

At least 19 recordsLinked to original sources
PubMed2005

Amitriptyline reduces rectal pain related activation of the anterior cingulate cortex in patients with irritable bowel syndrome.

BACKGROUND AND AIMS: Irritable bowel syndrome (IBS) is a disorder of intestinal hypersensitivity and altered motility, exacerbated by stress. Functional magnetic resonance imaging (fMRI) during painful rectal distension in IBS has demonstrated greater activation of the anterior cingulate cortex (ACC), an area relevant to pain and emotions. Tricyclic antidepressants are effective for IBS. The aim of this study was to determine if low dose amitriptyline reduces ACC activation during painful rectal distension in IBS to confer clinical benefits. Secondary aims were to identify other brain regions altered by amitriptyline, and to determine if reductions in cerebral activation are greater during mental stress. METHODS: Nineteen women with painful IBS were randomised to amitriptyline 50 mg or placebo for one month and then crossed over to the alternate treatment after washout. Cerebral activation during rectal distension was compared between placebo and amitriptyline groups by fMRI. Distensions were performed alternately during auditory stress and relaxing music. RESULTS: Rectal pain induced significant activation of the perigenual ACC, right insula, and right prefrontal cortex. Amitriptyline was associated with reduced pain related cerebral activations in the perigenual ACC and the left posterior parietal cortex, but only during stress. CONCLUSIONS: The tricyclic antidepressant amitriptyline reduces brain activation during pain in the perigenual (limbic) anterior cingulated cortex and parietal association cortex. These reductions are only seen during stress. Amitriptyline is likely to work in the central nervous system rather than peripherally to blunt pain and other symptoms exacerbated by stress in IBS.

Adult↗
PubMed2001

Delirium in mechanically ventilated patients: validity and reliability of the confusion assessment method for the intensive care unit (CAM-ICU).

CONTEXT: Delirium is a common problem in the intensive care unit (ICU). Accurate diagnosis is limited by the difficulty of communicating with mechanically ventilated patients and by lack of a validated delirium instrument for use in the ICU. OBJECTIVES: To validate a delirium assessment instrument that uses standardized nonverbal assessments for mechanically ventilated patients and to determine the occurrence rate of delirium in such patients. DESIGN AND SETTING: Prospective cohort study testing the Confusion Assessment Method for ICU Patients (CAM-ICU) in the adult medical and coronary ICUs of a US university-based medical center. PARTICIPANTS: A total of 111 consecutive patients who were mechanically ventilated were enrolled from February 1, 2000, to July 15, 2000, of whom 96 (86.5%) were evaluable for the development of delirium and 15 (13.5%) were excluded because they remained comatose throughout the investigation. MAIN OUTCOME MEASURES: Occurrence rate of delirium and sensitivity, specificity, and interrater reliability of delirium assessments using the CAM-ICU, made daily by 2 critical care study nurses, compared with assessments by delirium experts using Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria. RESULTS: A total of 471 daily paired evaluations were completed. Compared with the reference standard for diagnosing delirium, 2 study nurses using the CAM-ICU had sensitivities of 100% and 93%, specificities of 98% and 100%, and high interrater reliability (kappa = 0.96; 95% confidence interval, 0.92-0.99). Interrater reliability measures across subgroup comparisons showed kappa values of 0.92 for those aged 65 years or older, 0.99 for those with suspected dementia, or 0.94 for those with Acute Physiology and Chronic Health Evaluation II scores at or above the median value of 23 (all P<.001). Comparing sensitivity and specificity between patient subgroups according to age, suspected dementia, or severity of illness showed no significant differences. The mean (SD) CAM-ICU administration time was 2 (1) minutes. Reference standard diagnoses of delirium, stupor, and coma occurred in 25.2%, 21.3%, and 28.5% of all observations, respectively. Delirium occurred in 80 (83.3%) patients during their ICU stay for a mean (SD) of 2.4 (1.6) days. Delirium was even present in 39.5% of alert or easily aroused patient observations by the reference standard and persisted in 10.4% of patients at hospital discharge. CONCLUSIONS: Delirium, a complication not currently monitored in the ICU setting, is extremely common in mechanically ventilated patients. The CAM-ICU appears to be rapid, valid, and reliable for diagnosing delirium in the ICU setting and may be a useful instrument for both clinical and research purposes.

APACHE↗
PubMed2001

The impact of delirium in the intensive care unit on hospital length of stay.

STUDY OBJECTIVE: To determine the relationship between delirium in the intensive care unit (ICU) and outcomes including length of stay in the hospital. DESIGN: A prospective cohort study. SETTING: The adult medical ICU of a tertiary care, university-based medical center. PARTICIPANTS: The study population consisted of 48 patients admitted to the ICU, 24 of whom received mechanical ventilation. MEASUREMENTS: All patients were evaluated for the development and persistence of delirium on a daily basis by a geriatric or psychiatric specialist with expertise in delirium assessment using the Diagnostic Statistical Manual IV (DSM-IV) criteria of the American Psychiatric Association, the reference standard for delirium ratings. Primary outcomes measured were length of stay in the ICU and hospital. RESULTS: The mean onset of delirium was 2.6 days (S.D.+/-1.7), and the mean duration was 3.4+/-1.9 days. Of the 48 patients, 39 (81.3%) developed delirium, and of these 29 (60.4%) developed the complication while still in the ICU. The duration of delirium was associated with length of stay in the ICU ( r=0.65, P=0.0001) and in the hospital ( r=0.68, P<0.0001). Using multivariate analysis, delirium was the strongest predictor of length of stay in the hospital ( P=0.006) even after adjusting for severity of illness, age, gender, race, and days of benzodiazepine and narcotic drug administration. CONCLUSIONS: In this patient cohort, the majority of patients developed delirium in the ICU, and delirium was the strongest independent determinant of length of stay in the hospital. Further study and monitoring of delirium in the ICU and the risk factors for its development are warranted.

Delirium↗
PubMed2001

Evaluation of delirium in critically ill patients: validation of the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU).

OBJECTIVE: To develop and validate an instrument for use in the intensive care unit to accurately diagnose delirium in critically ill patients who are often nonverbal because of mechanical ventilation. DESIGN: Prospective cohort study. SETTING: The adult medical and coronary intensive care units of a tertiary care, university-based medical center. PATIENTS: Thirty-eight patients admitted to the intensive care units. MEASUREMENTS AND MAIN RESULTS: We designed and tested a modified version of the Confusion Assessment Method for use in intensive care unit patients and called it the CAM-ICU. Daily ratings from intensive care unit admission to hospital discharge by two study nurses and an intensivist who used the CAM-ICU were compared against the reference standard, a delirium expert who used delirium criteria from the Diagnostic and Statistical Manual of Mental Disorders (fourth edition). A total of 293 daily, paired evaluations were completed, with reference standard diagnoses of delirium in 42% and coma in 27% of all observations. To include only interactive patient evaluations and avoid repeat-observer bias for patients studied on multiple days, we used only the first-alert or lethargic comparison evaluation in each patient. Thirty-three of 38 patients (87%) developed delirium during their intensive care unit stay, mean duration of 4.2 +/- 1.7 days. Excluding evaluations of comatose patients because of lack of characteristic delirium features, the two critical care study nurses and intensivist demonstrated high interrater reliability for their CAM-ICU ratings with kappa statistics of 0.84, 0.79, and 0.95, respectively (p <.001). The two nurses' and intensivist's sensitivities when using the CAM-ICU compared with the reference standard were 95%, 96%, and 100%, respectively, whereas their specificities were 93%, 93%, and 89%, respectively. CONCLUSIONS: The CAM-ICU demonstrated excellent reliability and validity when used by nurses and physicians to identify delirium in intensive care unit patients. The CAM-ICU may be a useful instrument for both clinical and research purposes to monitor delirium in this challenging patient population.

Aged↗
PubMed2001

Ratio of free-to-total prostate specific antigen correlates with tumor volume in patients with increased prostate specific antigen.

PURPOSE: We evaluated the relationship between the ratio of free-to-total prostate specific antigen (PSA) and prostate pathology, including grade, stage and tumor volume, among patients with prostate cancer who underwent radical prostatectomy. MATERIALS AND METHODS: We prospectively analyzed 54 consecutive patients with prostate cancer who underwent radical prostatectomy and in whom frozen serum was available for assessment of free-to-total PSA ratio. Pathological review was done with whole mount sections, and total tumor volume was determined by planimetry. Comparison between free-to-total PSA ratio and pathological parameters was performed using the Pearson correlation coefficient. RESULTS: Among the 54 patients mean total and free-to-total PSA ratio were 5.81 and 14.2 ng./ml., respectively, and free-to-total PSA ratio directly correlated with prostate volume (p = 0.037), and inversely correlated with Gleason score (p = 0.012) and extracapsular disease (p = 0.0074). Furthermore, there was a significant relationship between free-to-total PSA ratio and pathological stage pT2a/b in 39 cases versus pT3a/b in 15 (p = 0.005). Overall, there was no correlation between free-to-total PSA ratio and tumor volume. However, among 37 patients with an increased PSA, defined as greater than 4.0 ng./ml., a significant inverse relationship between free-to-total PSA ratio and tumor volume was identified (p = 0.01). Among this subset there was only a weak correlation with prostate volume (p = 0.049). CONCLUSIONS: Our findings suggest that free-to-total PSA ratio may be predictive of tumor biology among those patients with a total PSA of greater than 4 ng./ml. as evidenced by good correlation with tumor grade and volume. This finding appears to be independent of prostate volume. These preliminary results suggest the need for additional studies among patients with an increased PSA designed to evaluate the potential role of free-to-total PSA ratio in combination with traditional clinical variables in the prediction of prostate cancer pathology.

Aged↗
PubMed2000

Spice extracts as dose-modifying factors in radiation inactivation of bacteria.

Three spices, chili, black pepper, and turmeric, were tested for the effect of their aqueous extracts on the sensitivity of three bacteria, Escherichia coli, Bacillus megaterium, and Bacillus pumilusspores, to gamma-radiation. It was found that the extracts of the three spices offered protection to these organisms against inactivation by gamma-radiation. These spice extracts were also tested for their protection of naked plasmid DNA. Radiation-induced degradation of plasmid pUC18 DNA was reduced in the presence of the spice extracts. The maximum protection was offered by the chili extract followed by that of black pepper and turmeric. The two known antioxidants, curcumin and piperine from turmeric and black pepper, respectively, were shown to protect the plasmid DNA from the degradation by gamma-radiation. Experiments with the plasmid pUC18 DNA indicated that the spice extracts probably protected microorganisms by protecting their DNA. These studies indicated the importance of spices among ingredients in food as dose-modifying factors during radiation processing.

Alkaloids↗
PubMed2000

A longitudinal analysis of the pediatric surgeon workforce.

OBJECTIVE: To describe the trends in the pediatric surgeon workforce during the last 25 years and to provide objective data useful for planning graduate medical education requirements. SUMMARY BACKGROUND DATA: In 1975, the Study on U.S. Surgical Services (SOSSUS) was published, including a model to survey staffing. A pediatric surgeon workforce study was initiated in conjunction with SOSSUS as a population, supply, and need-based study. The study has been updated every 5 years using the same study model, with the goals of determining the number and distribution of pediatric surgeons in the United States, the number needed and where, and the number of training programs and trainee output required to fill estimated staffing needs. This is the only such longitudinal workforce analysis of a surgical specialty. METHODS: Questionnaires were sent to 100 pediatric surgeons representing the 62 standard metropolitan statistical areas (SMSAs) in the United States with a population of 200,000 or more to verify the names and locations of all active pediatric surgeons and to gain information about the 5-year need for new pediatric surgeons by region. A program was developed to predict the number of pediatric surgeons relative to the total population and the 0-to-17-year-old population in the subsequent 30 years using updated data on the present number and ages of pediatric surgeons, age-specific death and retirement rates, projections of U.S. population by age group, and varying numbers of trainees graduated per year. As each 5-year update was done, previous projections were compared with actual numbers of pediatric surgeons found. The trends during the last 25 years were analyzed and compared and additional information regarding the demographics of practice, trends in reimbursement, and volume and scope of surgery was obtained. RESULTS: The birth rate has been stable since 1994. The 0-to-17-year-old population has been increasing at 0.65% per year; a 0.64% annual rate is projected to 2040. At present, 661 pediatric surgeons are distributed in every SMSA of 200,000 or more population, with an average age of 45 and an average age of retirement 65. The actual number of pediatric surgeons in each 5-year survey has consistently validated previous projections. Trainee output has increased markedly in the past 10 years. The rate of growth of the pediatric surgeon workforce at present is 50% greater than the forecasted rate of increase in the pediatric age group, and during the past 25 years the rate of growth of the pediatric surgeon workforce has been double that of the pediatric population growth. Nationally, significant changes in reimbursement, volume of surgery, and demographics of practice have occurred.

Adolescent↗
PubMed1999

Resolution of gastritis induced by Helicobacter pylori 4-5 weeks after successful eradication of infection using a triple therapy regimen of pantoprazole, amoxycillin and clarithromycin for one week.

UNLABELLED: This open-label study was designed to determine the extent of histological resolution of gastritis induced by Helicobacter pylori infection 4-5 weeks after successful eradication of the infection. Eradication was achieved using a triple therapy regimen consisting of a twice daily dose of pantoprazole 40 mg, clarithromycin 500 mg, and amoxicillin 1,000 mg taken for 1 week only. No other medications were given thereafter. Four biopsies were processed for histological examination of each patient, two from the antral and two from the corporeal mucosa, first at the start of the study and then again 4 weeks after cessation of the medication trial. Scoring for H. pylori colonization and the severity of gastritis was determined for each patient according to the Sydney system. 53 of 57 patients in this study had their H. pylori infection successfully eradicated by the regimen mentioned and could be histologically evaluated. According to the severity of gastritis in the antral mucosa, patients were studied in 3 groups: mild, moderate and severe gastritis. 17 of 19 cases with mild gastritis showed complete resolution of the inflammation, with residual inflammatory changes persisting in 2 cases only. 22 of the 26 cases with moderate gastritis showed almost complete recovery except for minor residual inflammatory changes as judged by irregularity of intracytoplasmic mucine storage. Persistent residual inflammatory changes in the lamina propria were detected in 4 cases. Of the 8 cases with severe gastritis 5 showed subsidence of the inflammatory changes, but the mucosa in these cases revealed some scarring, distortion of the glandular epithelium and atrophy. In 3 cases residual inflammation persisted. CONCLUSION: One-week therapy with a twice daily dose of pantoprazole 40 mg, clarithromycin 500 mg and amoxicillin 1,000 mg, used to eradicate H. pylori causing active inflammation of the gastric mucosa, has led to subsidence of the acute inflammatory changes in all the cases with residual inflammation persisting in 17%. Severe gastritis may cause irreparable damage to the gastric mucosa. The density of H. pylori colonization does not appear to be related to the severity of gastritis, nor to the successful eradication achieved.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1999

One-week triple regime therapy consisting of pantoprazole, amoxicillin and clarithromycin for cure of Helicobacter pylori-associated upper gastrointestinal diseases.

This study was designed to determine the efficacy and safety of 1-week triple therapy regime consisting of pantoprazole, amoxicillin and clarithromycin in the cure of Helicobacter pylori infection leading to duodenal ulcer disease and/or gastritis. Sixty-one patients (47 males, 14 females with a mean age of 34 years) belonging to different ethnic groups suffering from H. pylori-associated duodenal ulcer and/or gastritis for an average of 2.46 years were recruited. Having satisfied primary selection criteria, patients received pantoprazole 40 mg b.i.d., clarithromycin 500 mg b.i.d. and amoxicillin 1,000 mg b.i.d. for 7 days. All medications were stopped there after H. pylori eradication was determined 4-6 weeks after treatment by a repeat endoscopy, a rapid urease test, H. pylori culture and histology assessment as indicators of cure. All three tests must be negative to consider the infection to have been successfully eradicated. Fifty-seven patients completed the efficacy analysis per protocol. Dramatic symptomatic improvement was noted in most patients immediately after stopping treatment and it was sustained at 6 weeks. At the end of the study, the healing rate of duodenal ulcers (complete re-epithelialization) following 1-week treatment only, as indicated above, and without any maintenance therapy was 66.7%, that of gastritis was 55.7%, and that of erosions was 64.3%. The overall eradication rate for H. pylori, however, was 93% (95% CI 83.0-98.1%). Furthermore, histologic evaluation revealed a remarkable resolution in the activity of gastritis in all the patients who had successful eradication of the infection.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1999

Cytological diagnosis of adenoid cystic carcinoma breast--a case report.

The cytologic features of a case of adenoid cystic carcinoma of breast diagnosed on fine needle aspiration cytology (FNAC) in a 52 years old female are described. FNAC was carried out on outer quadrant of breast. The characteristic cytological features were numerous single to branching small round to Avoid cells at places forming microacini. Numerous pink hyaline globules of variable sizes were seen along with finger like projections containing basement membrane material.

Biopsy, Needle↗
PubMed1997

The effect of rings on microbial load of health care workers' hands.

BACKGROUND: The hands of health care workers (HCWs) serve as a major route for transmission of nosocomial infection. Although handwashing is known to reduce cross-transmission of infection, the influence of rings on the efficacy of handwashing and the carriage of bacteria on the hands has not been well established. METHODS: In this study, 50 HCWs with rings were paired by unit with 50 HCWs without rings. Cultures were obtained by use of a timed-friction rinse before and after a timed handwashing. Standard laboratory procedures were followed for identification of the bacteria. RESULT: When colony counts before handwashing are taken into consideration, a significant difference is seen after handwashing between the two groups (R2 = 0.56). The regression model showed that the slope was significantly steeper (p < 0.0014) for the group with rings. This effect is more apparent when the colony count on hands is greater than 1000 colony forming units before handwashing. CONCLUSIONS: A standardized, timed handwashing procedure was effective in decreasing the bioload of HCWs' hands. The effect of rings on the bioload was significant in this study.

Case-Control Studies↗
PubMed1997

Test for linear trend in 2 x K ordered tables with open-ended categories.

A method of evaluating trend (positive or negative) in 2 x K ordered tables is suggested for cases in which the scores for the first (K-1) categories are known a priori but the score for the last category is not known. Such a category is termed as open-ended category in this paper. Ordered tables with an open-ended category are often encountered while evaluating the Cochran-Armitage-Mantel (CAM) trend. In the present paper, the distribution of the test statistic is presented and simulations are carried out to check the asymptotics. The method is then exemplified by an existing data set.

Biometry↗
PubMed1996

Effect of menthol cigarettes on biochemical markers of smoke exposure among black and white smokers.

STUDY OBJECTIVES: Black smokers have been reported to have higher serum cotinine levels than do white smokers, and have higher rates of most smoking-related diseases, despite smoking fewer cigarettes per day. Another striking racial difference is the preference for mentholated cigarettes among black smokers. The contribution of menthol to variability in biochemical markers of cigarette smoke exposure (end-expiratory carbon monoxide and serum cotinine) was evaluated in a biracial sample. DESIGN: Descriptive cross-sectional. SETTING: A university smoking research laboratory. PARTICIPANTS: Sixty-five black and 96 white adult established smokers who were paid for their participation. MEASUREMENTS: Information was obtained through direct observation, self-report (interview and self-administered questionnaires), measurement of butts collected for a week, and laboratory analyses of the biochemical markers of exposure. RESULTS: Compared with the white smokers, the black smokers had significantly higher cotinine and carbon monoxide levels per cigarette smoked and per millimeter of smoked tobacco rod (both p < 0.001). After adjusting for race, cigarettes per day, and mean amount of each cigarette smoked, menthol was associated with higher cotinine levels (p = 0.03) and carbon monoxide concentrations (p = 0.02). CONCLUSIONS: The use of menthol may be associated with increased health risks of smoking. Menthol use should be considered when biochemical markers of smoke exposure are used as quantitative measures of smoking intensity or as indicators of compliance with smoking reduction programs. In addition, the effect of menthol on total "dose" should be considered in any efforts to regulate the amount of nicotine in cigarettes.

Adolescent↗
PubMed1995

Transferrin receptor expression in nonsmall cell lung cancer. Histopathologic and clinical correlates.

BACKGROUND: In the search for tumor-related antigens with survival-predictive value, previous studies have yielded varied conclusions regarding the expression of one such antigen, the transferrin receptor in lung cancer. The goal of this study was to define the frequency of expression of transferrin receptor in lung cancer specimens and gather preliminary data regarding the prognostic value of this tumor-related antigen. METHODS: Tissue immunoreactivity was studied with a murine monoclonal antibody to transferrin receptor in patients with nonsmall cell lung cancer who underwent surgical resection at the Medical Center Hospital of Vermont during the period from January, 1988, to May, 1991. RESULTS: The study group consisted of 32 patients (21 males and 11 females) with an average follow-up length of 27 months (standard deviation of 16 months). There were 17 patients with adenocarcinoma, 14 with squamous cell carcinoma, and 1 with large cell carcinoma. At the end of data accumulation, a total of 16 deaths had been recorded (8 with squamous cell, 8 with adenocarcinoma). Normal lung tissue did not stain for transferrin receptor; however, 13 of 17 (76%) adenocarcinomas, 13 of 14 (93%) squamous cell carcinomas, and the 1 large cell carcinoma stained positively for transferrin receptor. Staining for transferrin receptor was graded according to pattern and intensity and categorized as absent-weak or strong. Survival analysis was performed to evaluate patient outcome based on a variety of clinical and experimentally determined characteristics. Groups based on N-status (N0 vs. N1 + N2, P = 0.08), stage (Stage 1 vs. Stage 2 + 3 P = 0.13), age (younger than 60 vs. 60 years or older, P = 0.09), and transferrin receptor staining (absent-weak vs. strong, P = 0.14) achieved nearly significant differences in survival. Further analysis of the differences in survival for groupings based on transferrin receptor staining found that these differences in survival reached significance for patients with larger tumors (T2 or T3, P = 0.02). CONCLUSIONS: Transferrin receptor is expressed in the majority of lung cancers and the presence of transferrin receptor in nonsmall cell lung cancers may be an indicator of poorer prognosis in certain groups of patients.

Adenocarcinoma↗
PubMed1994

Upregulation of neuronal nitric oxide synthase and mRNA, and selective sparing of nitric oxide synthase-containing neurons after focal cerebral ischemia in rat.

Nitric oxide synthase-containing neurons are presumed to be resistant to neurodegeneration and neurotoxicity, however this resistance has not been demonstrated after focal cerebral ischemia. We therefore measured the temporal profile of neuronal nitric oxide synthase (NOS-I) mRNA and immunoreactivity and NADPH-diaphorase reactivity over a one week period after permanent middle cerebral artery (MCA) occlusion in 48 male Wistar rats and compared these data to ischemic cell damage as evaluated on hematoxylin and eosin (H & E) stained sections by light microscopy. NOS-I mRNA increased as early as 15 min after MCA occlusion in the ipsilateral striatum and maximal expression of NOS-I was found in the ipsilateral cortex and striatum 1 h after MCA occlusion. The numbers of NOS-I-containing neurons in the ipsilateral cortex and striatum were significantly greater (P < 0.05) than NOS-I-containing neurons in the contralateral hemisphere at 2-48 h after the onset of ischemia. The number of NOS-I-containing neurons peaked at 4 h after MCA occlusion. Neurons exhibited shrinkage or were swollen at 1 to 4 h after MCA occlusion. At 24-48 h after ischemia, neurons in the ischemic lesion appeared to be eosinophilic or ghost like on H & E stained sections. However, some of these neurons retained morphological integrity on the NOS-I immunohistochemical sections. At 168 h after ischemia, all neurons within the lesion appeared necrotic on H & E stained sections; however, scatterred neurons expressed NOS-I and NADPH-diaphorase. The rapid upregulation of NOS-I and mRNA in the ischemic lesion suggests that NOS-I is involved in focal cerebral ischemic injury; the expression of NOS-I by neurons that retain their morphological structure in the area of the infarct suggests that NOS-I-containing neurons are more resistant to the ischemic insult. Our data also indicate a close association of NOS-I immunoreactivity and NADPH-diaphorase reactivity in ischemic brain.

Amino Acid Oxidoreductases↗
PubMed1994

Chemokine expression in trinitrochlorobenzene-mediated contact hypersensitivity.

The expression of the murine IP-10 and MCP-1 genes has been examined in the skin of mice during contact hypersensitivity reactions to the hapten trinitrochlorobenezene (TNCB). In both naive and passively sensitized animals, challenge with TNCB resulted in elevated expression of both genes as early as 4 h as detected by Northern hybridization analysis. Twenty-four hours after challenge, expression was markedly reduced in naive animals but remained elevated in sensitized animals. This prolonged expression of chemokine gene products correlates with the tissue swelling response generally used as a measure of delayed-type hypersensitivity (DTH) in this model and suggests that the continued expression of these genes results from the stimulation of hapten-specific T helper cells. Examination of cell type expression patterns by in situ hybridization using 3H-radiolabeled riboprobes confirmed the results of Northern hybridization experiments. Both genes were expressed predominantly in cells exhibiting the morphology of connective tissue fibroblasts, although the distribution of cells positive for IP-10 mRNA expression differed from that of cells expressing MCP-1 mRNA. IP-10 expression was localized almost exclusively to a population of connective tissue cells surrounding the fur follicle. MCP-1 expression was rarely found associated with fur follicles but instead was distributed throughout the dermis in cells embedded in the collagenous extracellular matrix. Surprisingly, neither endothelial cells lining the small vessels located deep within the dermis nor epidermal keratinocytes were positive under any of the conditions utilized in the present study. Expression of both IP-10 and MCP-1 has been previously reported in a variety of distinct cell types in vitro. The present results indicate that only a subset of the cell types with such potential are stimulated to express these chemokine genes in vivo during hapten-mediated DTH responses, implying the presence of subtle cell type- and tissue-specific control mechanisms.

Animals↗