PubMed Health⌕ Search

Biomedical subjects

G Horowitz

Publications and source records attributed to G Horowitz.

At least 19 recordsLinked to original sources
PubMed2001

Quinolones and false-positive urine screening for opiates by immunoassay technology.

CONTEXT: Millions of assays are performed each year to monitor for substance abuse in various settings. When common medications cross-react with frequently used testing assays, false-positive results can lead to invalid conclusions. OBJECTIVE: To evaluate cross-reactivity of quinolone antimicrobials in common opiate screening assays and to assess the in vivo implications of this phenomenon. DESIGN, SETTING, AND PARTICIPANTS: The reactivity of 13 quinolones (levofloxacin, ofloxacin, pefloxacin, enoxacin, moxifloxacin, gatifloxacin, trovafloxacin, sparfloxacin, lomefloxacin, ciprofloxacin, clinafloxacin, norfloxacin, and nalidixic acid) was tested in 5 commercial opiate screening assays from September 1998 to March 1999. In 6 healthy volunteers, we confirmed the cross-reactivity of levofloxacin or ofloxacin with these opiate screening assays. MAIN OUTCOME MEASURE: Opiate assay activity (threshold for positive result, 300 ng/mL of morphine). RESULTS: Nine of the quinolones caused assay results above the threshold for a positive result in at least 1 of the assays. Four of the assay systems caused false-positive results for at least 1 quinolone. Eleven of the 13 compounds caused some opiate activity by at least 1 assay system. At least 1 compound caused opiate assay activity in all 5 assay systems. Levofloxacin, oflaxacin, and perfloxacin were most likely to lead to a false-positive opiate result. Positive results were obtained in urine from all 6 volunteers. CONCLUSION: Greater attention to the cross-reactivity of quinolones with immunoassays for opiates is needed to minimize the potential for invalid test interpretation.

4-Quinolones↗
PubMed1999

Reagentless blood analysis by near-infrared Raman spectroscopy.

BACKGROUND: Raman spectroscopy has advantages over infrared absorption spectroscopy. Combined with a novel multivariate technique, hybrid linear analysis (HLA), low prediction error is expected. METHODS: A near-infrared (NIR) light source excited Raman signals, and a charge coupled device (CCD) camera was used to collect the signal. Samples were collected from 69 individuals for 7 weeks. The standard multivariate calibration technique, partial least squares (PLS) and HLA were both used to analyze the collected spectra. A Clarke error grid was used to evaluate the usefulness of the glucose measurement in serum. RESULTS: The root mean squared error of prediction (RMSEP) for glucose in serum obtained with PLS is 21 mg/dL, and the RMSEP obtained with HLA is 17 mg/dL. In whole blood, the PLS RMSEP for glucose was 79 mg/dL, and HLA predictions had an RMSEP of 63 mg/dL. CONCLUSIONS: The measurement technique was robust over the 7-week period. HLA was shown to generate a lower prediction error than PLS. The predictions by both PLS and HLA were clinically acceptable. The result with whole blood requires further improvement.

Blood Chemical Analysis↗
PubMed1998

Evaluating noise induced hearing loss with distortion product otoacoustic emissions.

This study assessed the clinical efficacy of screening for noise induced hearing loss (NIHL) with distortion product otoacoustic emissions (DPOAE). DPOAEs were recorded from 76 military personnel (137 ears) aged between 17 and 41 years in response to equilevel 70 dB SPL primary stimulating tones. The 2f1-f2 DPOAE levels were correlated with audiometric thresholds at frequencies close to f2. Ears with normal audiograms, but with a history of military noise exposure, had DPOAEs that were significantly decreased in amplitude as compared to the ears of normal hearing non-exposed to noise subjects. These ears also had an increased absence of DPOAEs as compared with the ears of the normal hearing non-exposed to noise subjects. Although, in general, the DPOAE amplitudes and spectral frequency ranges reflected the audiometric NIHL configurations, in a number of cases DPOAEs were present for hearing losses up to 75 dB HL. As a consequence, DPOAEs correlated moderately and negatively with the audiometric thresholds. Applying test criteria designed to logically reflect NIHL, DPOAE sensitivity and specificity levels ranged between 0.51-0.90 and 0.63-0.25, respectively. These findings indicate that DPOAEs, recorded and analysed as described, are not sufficiently sensitive to serve as a single test to identify NIHL.

Acoustic Stimulation↗
PubMed1995

Evaluating cholesterol screening. The importance of controlling for regression to the mean.

OBJECTIVES: To determine the overall impact of a voluntary cholesterol screening program and to assess the importance of controlling for regression to the mean when evaluating the impact on higher-risk subgroups. DESIGN: Longitudinal study comparing baseline survey and cholesterol results with those obtained 17 months later, with adjustment for regression to the mean. SETTING: Participants were seen at three sites: an academic teaching hospital, an intermediate-care hospital, and a suburban community center. PARTICIPANTS: One thousand fifty-three participants were enrolled in a voluntary cholesterol screening program. MEASUREMENTS/MAIN RESULTS: Of 1053 study enrollees, 785 (75%) completed a follow-up questionnaire and 656 (62%) returned for follow-up cholesterol tests. Among all participants at high risk, measured cholesterol levels were 0.66 mmol/L (25.5 mg/dL) lower at follow-up, but 58% of this apparent change (0.38 mmol/L [14.7 mg/dL]) was attributable to the statistical phenomenon of regression to the mean. Among all participants at increased (both high and moderate) risk, after controlling for regression to the mean, reductions in cholesterol levels were significant for those younger than 60 years (-0.28 mmol/L [-10.8 mg/dL]; 95% confidence interval, -0.43 to -0.13; n = 390) but not for those 60 years or older (+0.007 mmol/L [+0.3 mg/dL]; 95% confidence interval, -0.16 to +0.17; n = 266). CONCLUSIONS: For subjects found at high risk in a cholesterol screening program, more than half of the apparent beneficial change in cholesterol level is attributable to regression to the mean. For participants older than 60 years, no clear benefit of cholesterol screening was documented.

Adult↗
PubMed1995

The safety of dental mini-magnets in patients with permanent cardiac pacemakers.

To evaluate the safety of prosthetic mini-magnets, 12 patients treated with implanted cardiac pacemakers were examined. Small cylindric magnets were applied one, two, and three at a time to constant points on the pacemaker under electrocardiographic monitoring. No influence on the pacemaker was detected in nine of the patients, but limited changes were encountered in three patients. However, the changes disappeared when the magnets were moved 1 cm away. The conclusion was that the use of mini-magnets in dental care in patients with implanted pacemakers is safe and acceptable.

Aged↗
PubMed1995

Noise-induced otoacoustic emission loss with or without hearing loss.

The association between audiometric hearing thresholds and click-evoked otoacoustic emission (CEOAE) spectral properties was examined in 129 adult subjects with and without a noise-induced hearing loss (NIHL). Subjects were grouped according to their "beginning of hearing loss frequency" and their exposure to hazardous noise. Emissions were recorded with an ILO88 Otodynamic Analyzer (Version 2.9) used in the default mode. CEOAE levels decreased as the hearing threshold increased at each of the test frequencies (1,2,3, and 4 kHz). At frequencies where hearing thresholds were worse than 20 dB HL, CEOAEs could not be recorded. Thus as the "beginning of hearing loss frequency" decreased, the frequency range of the emissions became narrower. The hearing threshold for which emissions were not recorded varied significantly between subjects, such that even at frequencies where the hearing threshold was 0 dB HL emissions were not always observed. Noise-exposed, normal-hearing subjects had reduced overall CEOAE power with a narrow frequency range as compared with normal-hearing, nonexposed to noise subjects. For our test conditions, the presence of CEOAEs necessarily suggests hearing thresholds of 20 dB HL or less at the corresponding frequency. A lack of emissions does not necessarily indicate hearing thresholds beyond 20 dB HL.

Acoustic Stimulation↗
PubMed1994

Effects of heparin and cardiac catheterization on serum lipoprotein and triglyceride levels.

This study determined whether heparin administration and procedures involving heparin significantly affect lipid measurement. Serum lipid and lipoprotein analyses (total cholesterol, triglycerides, high-density lipoprotein [HDL] cholesterol, low-density lipoprotein [LDL] cholesterol, apolipoprotein B, and apolipoprotein A-I) were performed at baseline and at several time points after (1) intravenous heparin or placebo in 6 healthy volunteers (group 1), (2) cardiac catheterization with heparin in 26 patients (group 2), and (3) peripheral angiography without heparin in 11 patients (group 3). In group 1, after heparinization, triglycerides decreased 50 +/- 12 mg/dl (-57%, p < 0.001 vs baseline and placebo) at 60 minutes. No changes were observed in other lipid or lipoprotein fractions. After cardiac catheterization (group 2), however, decreases were observed not only in triglycerides (58 +/- 26 mg/dl [-40%]), but also in total cholesterol (28 +/- 12 mg/dl [-14%]), LDL cholesterol (19 +/- 22 mg/dl [-15%]), apolipoprotein B (13 +/- 9 mg/dl [-14%]), and apolipoprotein A-I (21 +/- 14 mg/dl [-17%]) (p < 0.001 vs baseline for all), and HDL cholesterol (4 +/- 7 mg/dl [-3%], p = 0.07). With the exception of triglycerides, these values remained significantly decreased for > or = 24 hours. The change in HDL was variable: Whereas most patients had a decrease (n = 24), 2 patients had a dramatic increase (> 100%) after administration of heparin. Similar decreases in total cholesterol, LDL cholesterol, and apolipoproteins B and A-I were observed in group 3 undergoing peripheral angiography without heparin.(ABSTRACT TRUNCATED AT 250 WORDS)

Apolipoproteins↗
PubMed1991

[Deformities due to finger sucking].

Finger sucking can result in deformities of the fingers as well as the deformities well-known in orthodontics. Besides skin changes resulting from chronic irritation, more serious deformities in position or function of the fingers appear to occur. In these cases it is mostly the index finger that is affected. Upon ceasure of the habit the skin changes prove to be reversible; the deformities in position and function of the fingers however do not always display spontaneous improvement. A review of relevant literature and an account of two patients with characteristic case histories is given.

Adult↗
PubMed1988

Antibiotic release from an experimental biodegradable bone cement.

An experimental biodegradable bone cement [poly(propylene fumarate)-methylmethacrylate] (PPF-MMA) has been compared in vivo with polymethylmethacrylate (PMMA) as a carrier agent for local release of antibiotics. This approach is potentially applicable to the treatment of chronic osteomyelitis where the clinical goal is to achieve sustained high concentrations of antibiotics locally in the infected bone. In our experiments, gentamicin- and vancomycin-impregnated cylindrical PMMA and PPF-MMA cement specimens were implanted subcutaneously in rats, and blood and wound fluid samples were obtained over a 2-week period. Antibiotic levels were determined using immunoassays, and microbiologic activity was confirmed with agar diffusion techniques. The biodegradable PPF-MMA cement achieved and maintained considerably higher wound antibiotic levels than did PMMA cement. Vancomycin levels for the PPF-MMA cement were greater than 20 times those for the PMMA cement at all sampling times from 24 h to 14 days. For both cements, the serum antibiotic concentrations remained safely below maximum levels recommended for parenteral therapy. Mechanical testing of the PPF-MMA cement showed that admixture of 3% by weight of antibiotic did not adversely affect material properties. We conclude that this experimental biodegradable bone cement (PPF-MMA) can be used as a carrier to achieve high sustained local levels and low serum levels of antibiotics. Because it is biodegradable and thus does not require a secondary procedure for removal, it has special potential for use in treatment of chronic osteomyelitis.

Administration, Topical↗
PubMed1986

Regional isolated limb perfusion of melanoma intransit metastases using mechlorethamine (nitrogen mustard).

Forty-two patients with intransit metastases of melanoma in a limb were treated by isolated regional perfusion chemotherapy using mechlorethamine (nitrogen mustard). Group 1 (n = 12) underwent treatment at low dose, less than 0.35 mg/kg, or low temperature, less than 38 degrees C. Group 2 (n = 30) received higher doses, 0.35 to 0.6 mg/kg, plus heat at 38 degrees C to 41 degrees C. No patient had evidence of disease outside the limb at the time of perfusion. The median follow-up time was 48 months (range, 1 to 9 years). Of the 42 patients, 29 had measurable lesions that responded as follows: group 1, complete response (CR) in two of ten and partial response (PR) in none; group 2, CR in six of 19 and PR in six of 19. The combined CR and PR rate of 12 of 19 in group 2 was significantly higher than that of group 1 (P less than .05). CR lasted only 2 months in the two patients of group 1, but persisted in the six patients of Group 2, four of whom are still alive free of disease at 16, 21, 33, and 40 months. Relapse-free control of disease in the limb was achieved in 36% of the patients in group 2 at 24 months, compared with 0% in group 1 (P less than .05). An overall survival of 74% at 48 months was observed in group 2, significantly higher than that of 64% for group 1 (P less than .05). The status of the regional lymph nodes (RLN) and the number of metastases did not affect tumor response. However, 77% of RLN-negative patients survived 48 months, in contrast to only 38% of RLN-positive patients (P less than .05). One patient died postoperatively of myocardial infarction. No serious systemic toxicity developed. Two patients who underwent repeat salvage perfusions developed a reversible peripheral neuropathy in the limb. Limb function was good after treatment, and dramatically improved in patients who had advanced satellitosis that responded to treatment. These results suggest that heated limb perfusion using mechlorethamine at an adequate dose can offer long-term control of intransit metastases in approximately one third of these patients, with preservation of good limb function and possible prolongation of survival.

Adult↗
PubMed1985

Iron uptake by teeth and bones: a Mossbauer effect study.

Iron uptake (Fe2+ and Fe3+) by bones, teeth, and dental enamel was studied, in vivo and in vitro, by chemical, powder X-ray diffraction and Mossbauer spectroscopy methods. Atomic absorption tests have revealed the permanent uptake of small amounts of iron by dental enamel soaked in vitro in solutions containing Fe2+. Mossbauer spectra show that the iron attached to the dental enamel stays at the same valency it had in the soaking solutions. Mossbauer measurements of in vivo samples show that iron is present in bones and teeth mainly as Fe3+ (10% Fe2+ in teeth), in compound similar to FeOOH. Iron is released or exchanged from teeth at a much lower rate than from bones.

Animals↗
PubMed1985

Retinal changes in myotonic dystrophy: a clinicomorphological study.

This report appears to be the first ultrastructural study of the maculopathy and peripheral pigmentary retinopathy in myotonic dystrophy. Nine eyes from five patients observed during life are described. The findings were similar in all eyes, the retinal pigment epithelium in the macular region containing an accumulation of lipofuscin in large hyperpigmented cells. Pigment-laden profiles found in the subpigment epithelial space or subretinal space were interpreted as an attempt to discharge the pigment. Stress fibres of actin microfilaments were thrown into prominence by the irregularity of the pigment epithelium. In the periphery migration of retinal pigment cells into the retina occasionally resulted in the formation of bone corpuscles around occluded vessels, as occurs in retinitis pigmentosa; but more often the clumps were coarser and surrounded basement membrane material. Central and peripheral epiretinal membranes were also observed.

Cataract↗
PubMed1980

Asterixis following metrizamide myelography.

Two patients seen after lumbar myelography with metrizamide demonstrated transient confusion and asterixis. Metabolic etiologies were excluded. To our knowledge, these are the first reported cases of asterixis following myelography with metrizamide.

Brain Diseases↗
PubMed1976

Infectiousness of laryngeal tuberculosis.

Two patients with laryngeal tuberculosis in the absence of extensive pulmonary tuberculosis are presented. In both, tuberculin testing of household members failed to show infectiousness of their disease. This contradicts the commonly held view that laryngeal tuberculosis is invariably highly infectious. The extent and activity of pulmonary disease probably determines the infectiousness of patients with laryngeal tuberculosis rather than the laryngeal lesion per se.

Adult↗
PubMed1976

Calcium in tears, lacrimal gland fluid, and fluid from the other orbital glands.

Abnormal tear calcium concentrations, which might be expected in ocular and systemic disorders,may be obscured if tear calcium concentration varies with flow rate. The results of the present study indicated that tear calcium concentration is independent of flow rate with rates faster than those which occur with stimulated overflow tearing (i.e., 2 mu1 per minute), but with slower flow rates such as would be encountered with basal, nonstimulated tear flow, tear calcium concentration increases as flow rate decreases. In addition, at given flow rates, tear calcium concentration is the same as that in at least two components of tears, i.e., lacrimal gland fluid, uncontaminated by fluid from the other orbital glands, and fluid from the other orbital glands, uncontaminated by lcarimal gland fluid. It is apparent that only if calcium concentration is correlated with fluid flow rate will determination of calcium in tears and in the components of tears produce valid information not only about tear calcium levels in the presence of ocular and systemic diseases but also about the mechanism of secretion of calcium by the orbital glands.

Animals↗