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Biomedical subjects

B P Katz

Publications and source records attributed to B P Katz.

At least 19 recordsLinked to original sources
PubMed1999

Experimental infection of human volunteers with Haemophilus ducreyi does not confer protection against subsequent challenge.

Two groups of human volunteers were inoculated with 2 doses of live Haemophilus ducreyi 35000HP. The reinfection group consisted of 7 subjects who previously had participated in experimental infection with 35000HP to the pustular stage of disease. The control group consisted of 7 naive subjects. Papules developed at 92.8% (95% confidence interval [CI], 66.1%-99.8%) of sites inoculated with live bacteria, in the reinfection group, and at 85.7% (95% CI, 57.2%-98. 2%) of sites in the control group. Sixty-nine percent (95% CI, 36. 8%-90.9%) of papules evolved into pustules in the reinfection group, compared with 41% (95% CI, 15.2%-72.3%) in the control group. The recovery rates of H. ducreyi from surface cultures and the histopathology of biopsies obtained from both groups were similar. Thus, experimental infection to the pustular stage of disease does not provide protective immunity against subsequent challenge.

Adult↗
PubMed1999

Subsequent sexually transmitted infections among adolescent women with genital infection due to Chlamydia trachomatis, Neisseria gonorrhoeae, or Trichomonas vaginalis.

OBJECTIVE: To identify factors associated with subsequent sexually transmitted infection (STI) (within 1 year of initial infection) due to Chlamydia trachomatis, Neisseria gonorrhoeae or Trichomonas vaginalis. DESIGN: Prospective cohort study. SETTING: A sexually transmitted diseases clinic and four community-based primary care clinics for adolescents. PARTICIPANTS: Female patients (ages 15 to 19 years) with initial diagnosis of chlamydia, gonorrhea, or trichomonas. MAIN OUTCOME MEASURES: Subsequent infection by chlamydia, gonorrhea, or trichomonas. RESULTS: More than 40% of subjects were subsequently infected by at least one STI. Reinfection was common, but infections with sexually transmitted organisms other than the initial infecting organism were also common. Predictors of subsequent infection were black race, gonorrhea as the initial infection, two or more sex partners in the previous 3 months, and inconsistent condom use. CONCLUSIONS: Subsequent STI frequently follow an initial STI, but there is substantial variation in the causal organism. These data suggest the importance of comprehensive STI prevention programs for adolescents rather than organism-specific interventions.

Adolescent↗
PubMed1998

Reduced quadriceps strength relative to body weight: a risk factor for knee osteoarthritis in women?

OBJECTIVE: To determine whether baseline lower extremity muscle weakness is a risk factor for incident radiographic osteoarthritis (OA) of the knee. METHODS: This prospective study involved 342 elderly community-dwelling subjects (178 women, 164 men) from central Indiana, for whom baseline and followup (mean interval 31.3 months) knee radiographs were available. Lower extremity muscle strength was measured by isokinetic dynamometry and lean tissue (i.e., muscle) mass in the lower extremities by dual x-ray absorptiometry. RESULTS: Knee OA was associated with an increase in body weight in women (P = 0.0014), but not in men. In both sexes, lower extremity muscle mass exhibited a strong positive correlation with body weight. In women, after adjustment for body weight, knee extensor strength was 18% lower at baseline among subjects who developed incident knee OA than among the controls (P = 0.053), whereas after adjustment for lower extremity muscle mass, knee extensor strength was 15% lower than in the controls (P not significant). In men, in contrast, adjusted knee extensor strength at baseline was comparable to that in the controls. Among the 13 women who developed incident OA, there was a strong, highly significant negative correlation between body weight and extensor strength (r = -0.740, P = 0.003), that is, the more obese the subject, the greater the reduction of quadriceps strength. In contrast, among the 14 men who developed incident OA, a modest positive correlation existed between weight and quadriceps strength (r = 0.455, P = 0.058). No correlation between knee flexor (hamstring) strength and knee OA was seen in either sex. CONCLUSION: Reduced quadriceps strength relative to body weight may be a risk factor for knee OA in women.

Aged↗
PubMed1998

Standardization of the experimental model of Haemophilus ducreyi infection in human subjects.

Human volunteers were challenged with Haemophilus ducreyi. Twenty subjects were inoculated with 2 doses (approximately 30 cfu) of live and 1 dose of heat-killed bacteria at 3 sites on the arm. Eight subjects were assigned to biopsy 1 or 4 days after inoculation, and 12 were biopsied after they developed a painful pustular lesion or were followed until disease resolved. Papules developed at 95% of 40 sites infected with live bacteria (95% confidence interval [CI], 83. 1%-99.4%). In 24 sites followed to end point, 27% of the papules resolved, 69% (95% CI, 47.1%-86.6%) evolved into pustules, and 4% remained at the papular stage. Recovery rates of H. ducreyi from surface cultures ranged from 13% to 41%. H. ducreyi was recovered from biopsies of 12 of 15 pustules and 1 of 7 papules, suggesting that H. ducreyi replicates between the papular and pustular stages of disease.

Adult↗
PubMed1998

Chronic fluoride exposure does not cause detrimental, extraskeletal effects in nutritionally deficient rats.

On the basis of observations that endemic fluorosis occurs more often in malnourished populations, a series of studies tested the hypothesis that deficient dietary intake of calcium, protein or energy affects fluoride metabolism so that the margin of safe fluoride exposure may be reduced. The objective of the investigation was to determine whether changes in fluoride metabolism in nutritionally deficient rats resulted in manifestation of any extraskeletal toxic fluoride effects not observed in healthy animals. This investigation included two studies, one that monitored the effect of calcium deficiency on the effects of chronic fluoride exposure, and a second study that observed fluoride effects in rats that were deficient either in protein or in energy and total nutrient intake. Control and experimental rats received drinking water containing 0, 0.26 (5), 0.79 (15) or 2.63 (50) mmol fluoride/L (mg/L) for 16 or 48 wk. Control rats were fed optimal diets and experimental rats were fed diets deficient in calcium (Study 1) or protein (Study 2). An additional group of experimental rats (Study 2) was provided with a restricted amount of diet; thus these rats were deficient in energy and total nutrient intake. The intake, excretion and retention of fluoride were monitored; after the rats were killed, tissue fluoride levels and biochemical markers of tissue function were analyzed. Bone marrow cells were harvested from some of the rats, after 48 wk of treatment, for determining the frequency of sister chromatid exchange, a marker of genetic damage. Although there were significant differences among fluoride treatment groups in fluoride excretion and retention that resulted in significantly greater fluoride levels in tissues of the experimental rats, we were unable to detect any harmful, extraskeletal biochemical, physiologic or genetic effects of fluoride in the nutritionally deficient rats.

Animals↗
PubMed1998

Revision rates after knee replacement in the United States.

OBJECTIVES: Each year approximately 100,000 Medicare patients undergo knee replacement surgery. Patients, referring physicians, and surgeons must consider a variety of factors when deciding if knee replacement is indicated. One factor in this decision process is the likelihood of revision knee replacement after the initial surgery. This study determined the chance that a revision knee replacement will occur and which factors were associated with revision. METHODS: Data on all primary and revision knee replacements that were performed on Medicare patients during the years 1985 through 1990 were obtained. The probability that a revision knee replacement occurred was modeled from data for all patients for whom 2 full years of follow-up data were available. Two strategies for linking revisions to a particular primary knee replacement for each patient were developed. Predictive models were developed for each linking strategy. ICD-9-CM codes were used to determine hospitalizations for primary knee replacement and revision knee replacement. RESULTS: More than 200,000 hospitalizations for primary knee replacements were performed, with fewer than 3% of them requiring revision within 2 years. The following factors increase the chance of revision within 2 years of primary knee replacement: (1) male gender, (2) younger age, (3) longer length of hospital stay for the primary knee replacement, (4) more diagnoses at the primary knee replacement hospitalization, (5) unspecified arthritis type, (6) surgical complications during the primary knee replacement hospitalization, and (7) primary knee replacement performed at an urban hospital. CONCLUSIONS: Revision knee replacement is uncommon. Demographic, clinical, and process factors were related to the probability of revision knee replacement.

Aged↗
PubMed1998

The effect of chewing sugar-free gum after meals on clinical caries incidence.

To determine the effect of chewing sugar-free gum on caries incidence, the authors conducted a randomized clinical study. A total of 1,402 children in Puerto Rico, in grades 5 through 7 at baseline, completed the study. They were randomized by classroom into a control group or chewing gum group; those in the gum group were instructed to chew sugar-free gum for 20 minutes after each of three meals a day. Clinical and radiographic evaluations were performed at baseline and after two and three years. The results show that all subjects and high-risk subjects, respectively, in the gum group developed 7.9 percent and 11.0 percent fewer decayed, missing or filled surfaces than subjects in the control group. Based on these findings, the authors concluded that chewing sorbitol-based sugar-free gum after eating significantly reduces the incidence of dental caries.

Aspartame↗
PubMed1997

Quadriceps weakness and osteoarthritis of the knee.

BACKGROUND: The quadriceps weakness commonly associated with osteoarthritis of the knee is widely believed to result from disuse atrophy secondary to pain in the involved joint. However, quadriceps weakness may be an etiologic factor in the development of osteoarthritis. OBJECTIVE: To explore the relation between lower-extremity weakness and osteoarthritis of the knee. DESIGN: Cross-sectional prevalence study. SETTING: Population-based, with recruitment by random-digit dialing. PARTICIPANTS: 462 volunteers 65 years of age or older. MEASUREMENTS: Radiographs of the knee were graded for the presence of osteoarthritis. Knee pain and function were assessed with the Western Ontario and McMaster Universities Arthritis Index, the strength of leg flexors and extensors was assessed with isokinetic dynamometry, and lower-extremity lean tissue mass was assessed with dual-energy x-ray absorptiometry. RESULTS: Among participants with osteoarthritis, quadriceps weakness, but not hamstring weakness, was common. The ratio of extensor strength to body weight was approximately 20% lower in those with than in those without radiographic osteoarthritis. Notably, among women with tibiofemoral osteoarthritis, extensor weakness was present in the absence of knee pain and was seen in participants with normal lower-extremity lean mass (extensor strength, 30.1 lb-ft for those with osteoarthritis and 34.8 lb-ft for those without osteoarthritis; P < 0.001). After adjustment for body weight, age, and sex, lesser quadriceps strength remained predictive of both radiographic and symptomatic osteoarthritis of the knee (odds ratio for prevalence of osteoarthritis per 10 lb-ft loss of strength, 0.8 [95% CI, 0.71 to 0.90] for radiographic osteoarthritis and 0.71 [CI, 0.51 to 0.87] for symptomatic osteoarthritis). CONCLUSION: Quadriceps weakness may be present in patients who have osteoarthritis but do not have knee pain or muscle atrophy; this suggests that the weakness may be due to muscle dysfunction. The data are consistent with the possibility that quadriceps weakness is a primary risk factor for knee pain, disability, and progression of joint damage in persons with osteoarthritis of the knee.

Aged↗
PubMed1997

Lack of effect of long-term fluoride ingestion on blood chemistry and frequency of sister chromatid exchange in human lymphocytes.

Two studies were conducted to assess the potential for adverse physiologic and genotoxic effects of long-term fluoride ingestion in adults residing in three communities with varying water fluoride levels (0.2 ppm, 1.0 ppm, and 4.0 ppm). All were long-time (> or = 30 years) residents of their respective communities. Plasma and urine samples were collected for fluoride analyses. Additional plasma was collected to determine blood chemistry, and plasma lymphocytes were examined to determine the frequency of sister chromatid exchange. Significant differences in urine (P = 0.001) and plasma (P = 0.0001) fluoride levels were found in the three communities. Seven of the blood parameters were statistically different among the communities, although all were within the defined normal range of the pathology laboratory. Sister chromatid exchange frequency was statistically higher in the 4.0 ppm fluoride community as compared to the other communities. Because of the higher SCE frequency in the 4.0 ppm fluoride community, a second study was performed to determine if the increased frequency was potentially related to the fluoride level of the communal water supply. Of the 58 adults recruited; 30 had used city water and 28 had used well water (< or = 0.3 ppm fluoride) as their principal water source for 30 years. Data analyses showed that the sister chromatid exchange frequency did not differ between the groups, indicating that the increased sister chromatid exchange frequency was not related to the fluoride level of the communal water. The investigation provided evidence that the long-term ingestion of water containing 4.0 ppm fluoride did not have any clinically important physiologic or genotoxic effects in healthy adults.

Adult↗
PubMed1997

Effects of self-care education on the health status of inner-city patients with osteoarthritis of the knee.

OBJECTIVE: To evaluate a concise program of self-care education delivered by an arthritis nurse specialist as an adjunct to primary care for inner-city patients with knee osteoarthritis (OA). METHODS: An attention-controlled clinical trial; 211 inner-city patients with knee OA were assigned arbitrarily to education (E) or attention-control (AC) conditions. Group E received an individualized 30-60-minute educational intervention that emphasized nonpharmacologic management of joint pain, preservation of function by problem-solving, and practice of principles of joint protection. Brief telephone contacts 1 week and 4 weeks later monitored and reinforced new self-care activities. Group AC viewed a 20-minute standardized public education presentation on arthritis and received followup telephone calls (only to encourage continued participation in the study). Outcomes included the Health Assessment Questionnaire (HAQ) Disability and Discomfort Scales, 10-cm visual analog scales measuring knee pain at rest and while walking, and the Quality of Well-Being (QWB) scale. Assessments were made at baseline and at 4-month intervals for 1 year. RESULTS: A total of 165 subjects (78%) completed all assessments. After control for baseline status, group E had significantly lower scores for disability and resting knee pain throughout the year of postintervention followup (P < 0.05 for both). Effects were somewhat discordant. By 12 months, functional benefits had begun to wane, while the effect on resting knee pain had grown. The overall effects of education on walking knee pain, overall joint pain (by HAQ), and general health status (by QWB) were not significant. CONCLUSION: Self-care education for inner-city patients with knee OA, delivered as an adjunct to primary care, was found to result in notable preservation of function and control of resting knee pain. The magnitude of the observed effects compares well with those of more labor-intensive and time-consuming intervention models. However, more sustained preservation of function and consistent effects on pain may require prolonged, more proactive followup, either by the patient educator or by a trained clinical assistant dedicated to the task of supporting self-care by patients with knee OA.

Aged↗
PubMed1997

Comparison of general internists, family physicians, and rheumatologists managing patients with symptoms of osteoarthritis of the knee.

OBJECTIVE: To evaluate the nature, risks, and benefits of osteoarthritis (OA) management by primary care physicians and rheumatologists. METHODS: Subjects were 419 patients followed for symptoms of knee OA by either a specialist in family medicine (FM) or general internal medicine (GIM) or by a rheumatologist (RH). Management practices were characterized by in-home documentation by a visiting nurse of drugs taken to relieve OA pain or to prevent gastrointestinal side effects of nonsteroidal anti-inflammatory drugs (NSAIDs) and by patient report (self-administered survey) of nonpharmacologic treatments. Changes in outcomes (knee pain and physical function) over 6 months were measured with the Western Ontario and McMaster Universities Osteoarthritis Index. RESULTS: Patients of RHs were 2-3 years older (P = 0.035) and tended to exhibit greater radiographic severity of OA (P = 0.064) and poorer physical function (P = 0.076) at baseline than the other 2 groups. In all 3 groups, knee pain and physical function improved slightly over 6 months; however, between-group differences were not significant. Compared to drug management of knee pain by FMs or RHs, that by the GIMs was distinguished by greater utilization of acetaminophen and nonacetylated salicylates (P = 0.008), lower prescribed doses of NSAIDs (P = 0.007), and, therefore, lower risk of iatrogenic gastroenteropathy (P < 0.001). In contrast, patients of RHs were more likely than those of FMs and GIMs to report that they had been instructed in use of isometric quadriceps and range-of-motion exercises (P < or = 0.001), application of heat (P = 0.051) and cold (P < 0.001) packs, and in the principles of joint protection (P = 0.016). Neither physician specialty nor specific management practices accounted for variations in patient outcomes. CONCLUSION: This observational study identified specialty-related variability in key aspects of the management of knee OA in the community (i.e., frequency and dosing of NSAIDs, use of nonpharmacologic modalities) that bear strong implications for long-term safety and cost. However, changes in knee pain and function over 6 months were unrelated to variations in management practices.

Activities of Daily Living↗
PubMed1997

A comparison of ibuprofen versus acetaminophen with codeine in the young tonsillectomy patient.

OBJECTIVE: To compare the use of ibuprofen with the use of acetaminophen with codeine for posttonsillectomy management. BACKGROUND: We were not satisfied with our traditional pain-management practice for tonsillectomy patients. We hoped to find a new approach for improved patient comfort and avoid scheduled, abusable drugs such as codeine. DESIGN: Intervention, prospective, randomized control trial. Follow-up was 1 month. SETTING: University referral center; institutional pediatric practice, ambulatory. PATIENTS: 110 children undergoing tonsillectomy with or without other procedures. Consecutive patients were offered participation. Enrollees were randomly assigned to one of two classes and analyzed with the initial assignment. No patients withdrew for adverse effects, although 12 in group 2 used codeine and 5 of those used acetaminophen, whereas 2 in group 1 received ibuprofen. INTERVENTIONS: Patients received either acetaminophen with codeine (group 1) or ibuprofen (group 2) for postoperative pain control. MAIN OUTCOME MEASURES: The main outcomes, determined before initiation of the study, were assessment of (1) postoperative bleeding, (2) pain, (3) efficacy of relief of pain by drug, (4) nausea, (5) emesis, (6) readmission to hospital, (7) average temperature, and (8) highest temperature after surgery. RESULTS: The only statistically significant difference is less nausea in patients receiving ibuprofen (p = 0.0049). Of note, no difference existed in postoperative bleeding, pain, or temperature control. CONCLUSIONS: Ibuprofen is at least as effective as acetaminophen with codeine for postoperative pain control in children after tonsillectomy.

Acetaminophen↗
PubMed1997

Sex under the influence. A diary self-report study of substance use and sexual behavior among adolescent women.

OBJECTIVE: To evaluate the potential causal relationship between alcohol and drug use and behavior that increases the risk of sexually transmitted diseases. STUDY DESIGN: Longitudinal study conducted at a sexually transmitted diseases clinic and four community-based primary care clinics for adolescents. The participants were 82 female adolescents (age 16-19 years) who agreed to complete diaries recording each coital event. Subjects were participants in a larger study of prevention of reinfections by sexually transmitted organisms. The main outcome measure was condom use at each coital event. Predictor variables were usual pattern of condom use (when substances were not involved) and two event-specific measures: sex partner change and use of alcohol or drugs before intercourse. RESULTS: Average time span of the diaries was 9.2 weeks. Subjects recorded 1,265 coital events. Ninety-three substance-associated coital events were recorded by 22 subjects. Event-specific condom use was associated with usual pattern of condom use, but not with event-specific variables of partner change or substance use before intercourse. CONCLUSIONS: These data do not support the hypothesis that substance use causes alteration of adolescent women's behavior in a manner that increases risk of sexually transmitted diseases.

Adolescent↗
PubMed1997

Outcome implications for the timing of bilateral total knee arthroplasties.

Health Care Financing Administration data from 1985 to 1990 revealed 339,152 total knee arthroplasties of which 62,730 (18.6%) were bilateral procedures (simultaneous 112,922; staged 6 weeks, 4354; staged 3 months, 4524; staged 6 months, 9829; and staged 1 year 31,401). Medicare beneficiaries undergoing bilateral procedures were an average of 73 years of age; demographics revealed that among the various simultaneous and staged groups 57% to 69% were females, 90% were white, 85% to 90% had a diagnosis of osteoarthritis, and 30% to 40% were performed in rural hospitals. Between 1985 and 1990, surgical and vascular complications ranged from 2.4% to 4% and 4.1% to 6.8%, respectively, for all types of bilateral staged and simultaneous total knee arthroplasties. All differences were statistically significant. After controlling statistically for demographic variables and diagnoses, a surrogate for case mix, it was found that individuals electing simultaneous bilateral arthroplasties experienced twice the number of intensive care days than those choosing staged procedures. Days in the intensive care unit were double when done simultaneously instead of staged (0.48 versus 0.21). Nosocomial infections were similar within groups (10% versus 13%); however, wound infections were nearly half when done simultaneously (0.5% versus 1%) versus in a staged fashion. Length of stay and cost were much less for the simultaneous procedure group who were sicker as measured by the number of diagnoses. Mortality at 30 days was highest for the simultaneous procedure group (.99%) versus staged 3 or 6 months (0.30%); however, by 2 years it was close to 4% for all groups. Staging the procedure 3 to 6 months seems to offer the fewest disadvantages, is only slightly more expensive, and has the lowest mortality rate.

Age Factors↗
PubMed1996

Risk factors for nonelective hospital readmissions.

We previously reported a predictive model that identified potentially modifiable risk factors for nonelective readmission to a county hospital. The objectives of this study were to determine if those risk factors were generalizable to a different population. We found that the previously reported risk factors were generalizable, and other potentially modifiable risk factors were identified in this population of veterans. However, further research is needed to establish whether or not the risk factors can be modified and whether or not modification improves outcomes.

Aged↗
PubMed1996

Absence of detrimental effects of fluoride exposure in diabetic rats.

This study is part of a comprehensive programme to investigate fluoride toxicity and the hypothesis that fluoride ingested by "medically compromised' animals will result in altered physiological function. Its objectives were to monitor fluoride retention, tissue fluoride concentrations and genetic variables in diabetic and control rats chronically exposed to fluoride, and to determine whether or not adverse effects occurred. Male, Zucker fatty diabetic rats and Zucker age-matched lean controls were fed a low-fluoride diet ( < 1.2 parts/10(6) F-) ad libitum and received 0, 5, 15 or 50 parts/10(6) fluoride in their drinking water for 3 or 6 months. Fluoride metabolic balance was determined for 4 days before the end of each study phase. Plasma and urine were analysed for biochemical markers of tissue function, and plasma, urine, faeces and tissues were analysed for fluoride. Bone marrow cells from animals killed after 6 months of treatment were examined for frequency of sister chromatid exchange, a marker of genetic damage. The diabetic rats consumed, excreted and retained significantly greater amounts of fluoride than the controls (p < 0.05). There were dose-related increases in fluoride excretion, retention and tissue concentrations in both classes of animals, which were significantly greater in the diabetic rats. In spite of greater amounts of fluoride in the tissues of diabetic animals, there was no evidence, under these experimental conditions, that any of the fluoride exposures tested caused measurable adverse effects on the physiological, biochemical or genetic variables that were monitored.

Analysis of Variance↗