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Biomedical subjects

P Rivera

Publications and source records attributed to P Rivera.

At least 19 recordsLinked to original sources
PubMed1999

[Evaluation of a fast urease test for the detection of Helicobacter pylori].

Helicobacter Pylori colonize the gastric mucosa and their adaptation to this environment is related with its high activity urease. This enzyme hydrolyzes the gastric urea, neutralizing the acid environment of the bacteria. Based on that reaction numerous presumptive diagnosis tests, have been developed using a solution of urea (usually 6%) with a pH indicator (usually 0.05% fenol-red); nevertheless, the color changes are so light that some persons do not detect it. For that reason, a modification of that reaction was proposed using a mix of pH indicators (0.05% fenolred and 0.002 bromothymol blue) which induces a color change from light green to deep purple. Also, the reaction of urease was evaluated using only bromothymol blue. The reaction using fenol red as indicator showed the higher values for sensitivity of 58.8% and the specificity of 66.6%; whereas using only bromothymol-blue those values were 46 y 71.4% respectively. The efficiency of the test using fenol-red or the mix of this bromothymol- was 64.2 y 62.2%, respectively; however, the mix of indicators induce a change color easily detected, because of changes from ligh-green to deep-purple.

Bromthymol Blue↗
PubMed1998

Hepatitis B vaccination program at a New York City hospital: seroprevalence, seroconversion, and declination.

BACKGROUND: Despite implementation of hepatitis B vaccination programs, 2 problems have prevented full vaccine-induced protection of health care workers (HCWs). About 10% to 12% of vaccinated HCWs do not develop antibody, and many HCWs continue to decline vaccination. To determine the effectiveness of our hepatitis B vaccine program, we studied rates of postvaccination seroconversion and vaccine declination. METHODS: Employee health service records were used to determine demographic features, hepatitis B surface antibody serostatus at baseline, serologic response to vaccine, and declination or acceptance of vaccine. RESULTS: About 26% of HCWs were seropositive at baseline, including those vaccinated before employment. Higher seroprevalence rates were seen among those born outside the United States, nurses, and laboratory workers. Seroconversion occurred in only 79% of HCWs who completed a 3-vaccine series. Increasing age was the only significant risk for failure to convert. Declination rates overall were about 45% and were lowest in HCWs who have jobs that included potential exposure to blood. CONCLUSION: Hepatitis B seroprevalence among HCWs at our hospital is higher than in many other urban hospitals in the United States; over postvaccination seroconversion rate is substantially lower; and our declination rate of 45% resembles other published series. Declination of vaccine and failure to respond to vaccine continue to thwart achievement of full control of this preventable occupational infection.

Adult↗
PubMed1998

Postexposure prophylaxis for human immunodeficiency virus: frequency of initiation and completion of newly recommended regimen.

Recent evidence demonstrating the efficacy of zidovudine, as well as experience with protease inhibitors, led to revision of recommendations for occupational exposures to human immunodeficiency virus-infected blood. At our hospital, this resulted in significant increases in rates of reported exposures and prophylaxis initiation. Among 10 healthcare workers given three-drug, protease-inhibitor-containing regimens, five completed 4 weeks, two completed 4 weeks of two drugs, and three stopped due to intolerance. Three workers missed work due to side effects.

Anti-HIV Agents↗
PubMed1998

[Magnetic resonance cholangiopancreatography (MRCP) versus endoscopic retrograde cholangiopancreatography (ERCP): diagnostic usefulness].

Magnetic resonance cholangiopancreatography (MRCP) is a new noninvasive technique to examine the biliopancreatic tract that have a high diagnostic accuracy. Thus it becomes an appealing modality that can avoid invasive approaches. The purpose of this study was to evaluate the sensitivity and specificity of MRCP in comparison to endoscopic retrograde cholangiopancreatography (ERCP). We studied 41 patients (24 male, 17 female), median age 64.2 years (range 20 to 86 years), in which MRCP and later ERCP were performed; results of both techniques were compared. In the assessment of biliary tract (n = 39), sensitivity/specificity was 100/94.4% in normal bile ducts (n = 18); 100/100% in choledocholithiasis (n = 13); 100/100% in sphincter of Oddi dysfunction (n = 2), and 100/83.3% in neoplasm (3 ampullary tumors, 2 cholangiocarcinomas). In the evaluation of pancreatic duct (n = 32), sensitivity/specificity was 100/95.8% in normal pancreatic duct (n = 23); 80/100% in chronic pancreatitis (n = 5), and 100/75% in pancreatic carcinoma (n = 3). MRCP has very high sensitivity and specificity in the evaluation of the biliary and pancreatic ducts, and can avoid to perform purely diagnostic ERCP, although further studies are required to better assess the effectiveness of the technique.

Adult↗
PubMed1998

[Focal nodular liver hyperplasia of atypical presentation].

Focal nodular hyperplasia is a benign hepatic tumor that usually appears in young women. Diagnosis of focal nodular hyperplasia is often incidental when an ultrasonography or computed tomography is performed by other reasons, because its course is generally asymptomatic; the presence of a central fibrous scar is characteristic. Management in focal nodular hyperplasia must be conservative, with ultrasonographic follow-up, and it only must be treated when patients are symptomatics or in case of tumoral enlargement. We report a case of FNH in which symptomatic presentation and the absence of central stellate scar in ultrasonography, computed tomography and magnetic resonance leads to a misdiagnostic of hepatic adenoma, that conditioned a surgical resection. The later examination was diagnostic of focal nodular hyperplasia.

Adenoma↗
PubMed1997

Benefit of two-step PPD testing of new employees at a New York City hospital.

BACKGROUND: Recent concern about nosocomial transmission of tuberculosis has led hospitals to scrutinize employee tuberculin conversion rates. The Centers for Disease Control and Prevention recommends two-step testing of new employees to limit the booster phenomenon. The cost of such a program and its subsequent yield have not recently been examined. METHODS: Employee health records were retrospectively reviewed of persons hired from 1993 and 1994 at St. Clare's Hospital in New York City, all of whom received two-step testing at time of initial employment. RESULTS: Of 262 new employees, 107 (41%) had positive tuberculin results on initial testing. The results of 15 (9.7%) of the remaining 155 patients became positive on two-step testing administered 1 week later. Persons with a positive second test result were significantly more likely to be male or foreign born or to have received previous bacille Calmette-Guérin vaccination. Identification of these 15 persons and exclusion of them from probable subsequent conversion prevented an almost 50% increase in the annual conversion rate at our hospital, from 3.2% to 4.7%. CONCLUSION: Two-step tuberculin testing is an essential means of identifying persons with a baseline positive tuberculin test result, thus allowing accurate reporting of subsequent employee tuberculin conversions.

Adult↗
PubMed1997

Biological and chemical study of paico (Chenopodium chilense, Chenopodiaceae).

The methanolic extract of the aerial portion of Chenopodium chilense Schrad., used in Chilean traditional medicine as a remedy for stomach-ache, has been found to exert the major spasmolytic activity in acetylcholine contracted rat ileum. This extract, with a complex flavonoid patterns on thin layer chromatography (TLC) analysis, is practically non-toxic both for rats and brine shrimp Artemia salina in acute toxicity test.

Acetylcholine↗
PubMed1997

Does a cheaper mask save money? The cost of implementing a respiratory personal protective equipment program.

OBJECTIVE: To determine the annual cost of implementing and maintaining a respiratory personal protective equipment (PPE) program at an urban hospital. SETTING: St Clare's Hospital and Health Center, a 250-bed hospital in Manhattan that treats 60 to 100 cases of tuberculosis annually. METHODS: Review of Purchasing Department records for all masks acquired by the hospital from 1992 to 1995, and an estimate of administrative time spent developing and implementing the guidelines recommended by various agencies during the study interval. RESULTS: Respiratory isolation was provided for 6,360 to 10,883 days annually during the 4-year interval. Yearly costs for the PPE program ranged from $86,560 to $175,690. Of note, the daily cost for a respiratory isolation day decreased dramatically between 1994 and 1995 ($25/day to $13/day), when the high-efficiency particulate air-filter (HEPA) respirator was used by all staff. The decrease occurred because of lower administrative costs and a sharp decrease in the numbers of HEPA units purchased. Objective measures of worker compliance with HEPA respirators demonstrated the decrease was not due to less HEPA use but rather that employees were using each HEPA unit for several weeks, as recommended. CONCLUSION: We found a significant decrease in cost in the second year of our HEPA program due to increasing employee familiarity with the program. Newly approved, cheaper, but less durable, N-95 masks are unlikely to withstand multiple wearings and may be discarded after a few uses. Thus, cheaper masks may result in a more expensive PPE program.

Cost-Benefit Analysis↗
PubMed1997

Risk of tuberculin conversion according to occupation among health care workers at a New York City hospital.

Concern about the risk to health care workers of occupationally acquired tuberculosis has resulted in extensive and frequently revised guidelines from the Centers for Disease Control and Prevention (CDC). Most recent studies, however, have determined that community, rather than occupational, exposure is the more significant risk for tuberculin conversion. To assess the relative contribution of community versus occupational risk, we reviewed the health records of 1,303 persons employed from 1991 to 1994 at St. Clare's Hospital in New York City, a hospital with a high tuberculosis case-rate. Demographic information included age, gender, postal zone of residence, country of birth, and BCG vaccination status, while occupations were placed into one of five groups. In multivariate analysis, occupation was significantly associated with risk of tuberculin conversion, while postal zone of residence was not. The group that included housekeeping, laundry, and security personnel and the physician-nurse group had the highest conversion rates. After implementation of CDC guidelines, there was a significant improvement in the employee tuberculin conversion rate. At our hospital, occupation was strongly associated with risk of tuberculin conversion.

Female↗
PubMed1997

[Cancer of the prostate: evaluation of the expression of the mutated protein of the 53 tumor suppressor gene].

UNLABELLED: Prostate cancer is the most common tumour in men, and is most frequently established late in life. The objective of the article is to determine the protein expression of gene p53 in prostate cancer and to correlate the findings with clinical, morphological and epidemiological parameters. MATERIAL AND METHODS: Immunohistochemical techniques with monoclonal antibody used to study the gene p53 expression. The study included 35 prostate carcinoma: 4 cases in stage A; 5 cases in stage B; 12 in stage C and 14 in stage D. The control group consisted in 10 benign prostate hyperplasia. Average age was 66.8 (SD +/- 6.7 years). RESULTS: Positive staining for gene p53 protein was seen in 11 of the 35 cases (31.4%). All stage A and B tumours were negative; however, stage C and D tumours were positive in 16 and 64% cases respectively. In the control group all cases were gene p53 negative. No statistical relationship was seen between Gleason Index and positive results for p53. There was a significant difference between gene 53 expression and clinical stage. CONCLUSIONS: Results show that the immunohistochemical expression of gen p53 mutated protein keeps no relation to Gleason's rating index and is seen with significantly higher frequency in advanced, primarily stage D tumours.

Adenocarcinoma↗
PubMed1997

[Collagenous colitis: presentation of 12 cases].

Collagenous colitis (CC) is a cause of chronic aqueous diarrhea with normal radiologic study and endoscopic appearance of the colonic mucosa. Histologically, it is defined by the presence of a thickened subepithelial collagenous band and inflammatory changes of the mucosa. The cause of CC is currently unknown, although several mechanisms have been proposed, such as an inflammatory, autoimmune, origin, disregulation in collagen synthesis, plasma vasculosis and a possible role of bacterial or drug toxins. The clinicopathological data of 12 patients (9 females and 3 males) with a mean age of 52.4 years diagnosed by histologic criteria are presented. Aqueous diarrhea was observed in all the patients with a mean number of 5.4 stools/day during a time period between 3 weeks and 10 years (mean, 14.7 months). In a 6 patients allergies and/or associated diseases, mainly rheumatologic diseases were found. Laboratory and endoscopic data were normal or unspecific, with colon biopsy being carried out in all the patients. Several treatments were tested with good response with sulphasalazine derivatives, corticoids, antibiotics, and mebeverine, with no solution to the diarrhea in 2 patients. A review of the literature is also provided.

Adult↗
PubMed1997

Rotavirus and coronavirus outbreak: etiology of annual diarrhea in Costa Rican children.

In Costa Rica, an annual outbreak of infant diarrheal disease (December and January) was reported since 1976, and rotavirus was incriminated later as the main etiological agent (1976-1981). Apparently the disease has not been systematically studied in Costa Rica after 1981. For that reason the occurrence of the outbreak was retrospectively documented for 1993-1995 and etiology was studied in 48 children treated for diarrhea at the Nacional Children Hospital (capital city of San Jose) during December, 1994 and January, 1995. Rotavirus (33%) and coronavirus (27%) were the main agents. To our knowledge, this is the first time that these viruses are incriminated in an outbreak of diarrhea.

Child↗
PubMed1996

Pneumococcal keratitis, bacteremia, and septic arthritis in an asplenic patient.

We report the case of a 66-year-old black woman who presented with concomitant acute infectious keratitis, bacteremia, and septic arthritis caused by Streptococcus pneumonia. The septic arthritis resolved rapidly with surgical drainage and intravenous antibiotics, but despite aggressive topical and intravenous antibiotic therapy for the infectious keratitis, the cornea perforated, the patient developed endophthalmitis, and the eye eventually was eviscerated. To the best of our knowledge this is the first reported case of this nature. This patient had undergone splenectomy > 50 years prior to developing these infections. Although the risk of serious infection in clinically significant bacteremia is greatest in the perioperative period after splenectomy, these patients are at increased risk of such events for a lifetime. Because encapsulated bacteria, especially Pneumococcus, pose the greatest risk of sepsis and infection in asplenic patients, pneumococcal vaccination of penicillin prophylaxis must always be considered in these patients. A careful and complete medical history and systemic evaluation remain a crucial element of the evaluation and management of serious infectious keratitis.

Aged↗
PubMed1996

[Splenic infarction].

A 53-year-old male suffered splenic infarction etiologically related to atrial fibrillation and non-obstructive hypertrophic cardiomyopathy. The main clinical manifestations were a one-month history of epigastric and left upper quadrant pain, with tenderness to palpation in the later zone. Laboratory tests revealed a slight leucocytosis (14.700) with left shift and a marked increase in LDH concentration (945 IU). Abdominal CAT and arteriography established the diagnosis, Echography proved normal. Patient evolution was satisfactory with conservative medical treatment. We conclude that splenic infarction should be considered in all cases of acute or chronic pain in the left hypochondrium. The diagnosis is established by CAT, arteriography and hepatosplenic gammagraphy. Medical management is initially advocated, surgery being reserved for those cases involving complications or in which diagnosis is not clear. Emphasis is placed on the main etiological, clinical, diagnostic and management characteristics of splenic infarction.

Angiography↗
PubMed1996

[Response of lymphocytes and cytokines in patients with superficial bladder cancer treated with 1 mg of BCG vaccine instillations].

It was carried out a study of lymphocytes CD3, CD8 and cytokines in the blood of 13 patients, with superficial bladder cancer, and treated by instillations with BCG vaccine, with a dose of 1 mg. in an annual scheme, being related them before and after treatment. A control group of 10 patients without bladder cancer and without vaccine instillations were compared. The measurings took place in a blind way, previous to BCG treatment, 15 days, 3 days, 3 months, 6 months and 12 months of treatment. It was observed in postBCG treatment, a significative increase in the count of CD3 lymphocytes and the CD4/CD8 cociente (both, P < 0.05). Concerned to cytokines, a significative increase was only demonstrated by interleukin-2 in the post BCG group (P < 0.05). In both (lymphocytes and cytokines) the control groups didn't demonstrate statistics signification. The studies where analysed by means of ANDEVA test, under 2 x 2 cross over design, student t and no parametric tests. In conclusion, bladder instillations of 1 mg. of BCG vaccine as prophylactic treatment of superficial bladder cancer, it's capable of developing lymphocytic answer and stimulate the increase of interleukin-2 in the serum.

Adjuvants, Immunologic↗
PubMed1995

Dramatic decrease in tuberculin skin test conversion rate among employees at a hospital in New York City.

BACKGROUND: The Centers for Disease Control and Prevention recently issued updated guidelines for preventing the transmission of tuberculosis in health care facilities. Many recommendations, including the use of high-efficiency particulate air filter respirators, are expensive to implement and of unproven efficacy. We therefore reviewed the tuberculin skin test conversion rate among our employees from 1991 to 1993, before introduction of high-efficiency particulate air filter respirators. During this period, several other improvements in tuberculosis control were implemented. METHODS: Employee tuberculin test conversion rates were reviewed by 6-month interval from 1991 to 1993. RESULTS: Throughout the study period, several tuberculosis control measures were implemented, including early isolation of patients with suspected cases of tuberculosis in rooms with negative-pressure ventilation, placement of germicidal UV light fixtures into patient rooms and common areas, and use of Technol shields (Technol, Inc., Fort Worth, Texas) (1991), particulate respirators (1992), and dust-mist-fume respirators (1993). With these improvements, the conversion rate among employees fell from 20.7% in the first 6 months of 1991 to 5.8% in the latter half of 1993. CONCLUSIONS: The rate of skin test conversion among our employees decreased before introduction of high-efficiency particulate air filter respirators. This suggests that nosocomial spread of tuberculosis can be decreased by means of previously established, less costly methods.

Cross Infection↗