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Biomedical subjects

L Roth

Publications and source records attributed to L Roth.

At least 37 records · Page 2Linked to original sources
PubMed1996

Submillimeter-resolution MR of the endolymphatic sac in healthy subjects and patients with Menière disease.

PURPOSE: To evaluate the utility of submillimeter resolution MR imaging for direct depiction of functional soft-tissue components of the intraosseous endolymphatic duct and sac in healthy subjects and in patients with Menière disease. METHODS: Axial MR images were acquired of 14 patients with Menière disease and 14 healthy volunteers at 1.5 T with a short-echo-time steady-state 3-D gradient-echo sequence. Seven volunteers and eight patients were also studied with a T1-weighted 3-D spoiled gradient-echo sequence. T1/T2 relaxation times were estimated from studies with multiple flip angles. RESULTS: Independent of the acquisition method, intraosseous endolymphatic ducts and sacs were seen unambiguously in the ears of 20 of 21 healthy subjects but in only four of 12 asymptomatic and two of 10 symptomatic ears of patients with Menière disease. Other labyrinthine structures were well depicted in all subjects. Furthermore, shorter relaxation times were measured for the contents of the vestibular aqueduct than for other labyrinthine structures. CONCLUSION: In our high-resolution study, the intraosseous portions of the endolymphatic ducts and sacs were depicted in most of the healthy subjects. They were frequently not seen in either ear of patients with unilateral Menière disease, presumably because of their small size.

Adult↗
PubMed1995

Analysis of intact hopanoids and other lipids from the bacterium Zymomonas mobilis by high-performance liquid chromatography.

Hopanoids and other lipids were extracted from Zymomonas mobilis and quantitatively analyzed by high-performance liquid chromatography. Previous methods for hopanoid analysis required derivatization of the hopanoids via periodate oxidation or acetylation. The current method employs a normal-phase silica gel column, a ternary gradient of hexane-isopropanol-water-triethylamine, and detection with a flame ionization detector. Three major hopanoid classes were separated and quantified by this new method, and together they comprised 30 to 40% of the total lipid in these cells. Mass spectrometry confirmed that chemical structures of these hopanoids were consistent with those previously proposed. In addition, several other common lipid classes (free fatty acids and six classes of common phospholipids), comprising the remaining 60 to 70% of the total lipids, were also separated and quantified. This new chromatographic method represents the first technique for the analysis and purification of intact hopanoids. This method should be useful for the analysis and purification of hopanoids from other bacterial species.

Chromatography, High Pressure Liquid↗
PubMed1995

Outpatient oral sulindac to prevent recurrence of preterm labor.

OBJECTIVE: To assess the efficacy and safety of oral sulindac in preventing the recurrence of preterm labor. METHODS: This was a randomized, double-blind, placebo-controlled study of patients between 24-34 weeks' gestation with preterm labor treated with intravenous magnesium sulfate. After successful tocolysis, patients were randomized by the pharmacy to receive either oral sulindac (200 mg) or placebo (once orally every 12 hours) for 7 days. RESULTS: Sixty-nine patients were enrolled (34 in the sulindac group, 35 controls). No significant differences were found with respect to time gained in utero (40 +/- 4.4 versus 31 +/- 3.4 days, P = .1), delivery at more than 35 weeks' gestation (20 versus 18, P = .70), recurrent preterm labor (11 versus 13, P = .88), birth weight (2528 +/- 646 versus 2459 +/- 707 g, P = .68), or time spent in the neonatal intensive care unit (4.2 +/- 12.9 versus 5.7 +/- 13.5 days, P = .63) for the sulindac and control groups, respectively. However, in women who failed therapy (ie, those who delivered before 37 weeks' gestation or required readmission for tocolysis), there was a significantly longer interval between the start of therapy and failure in the sulindac group (25.9 +/- 3.4 days, n = 26) than in the control group (15.2 +/- 2.8 days, n = 25; P < .05). CONCLUSION: The use of oral sulindac for 1 week after successful parenteral tocolysis failed to reduce the overall rate of preterm birth. In women who delivered prematurely or required readmission for tocolysis, oral sulindac significantly prolonged the interval from the start of therapy until delivery or readmission. Moreover, this benefit was achieved without observable adverse effects on the fetus.

Administration, Oral↗
PubMed1995

Interpretation of liver biopsies.

Liver biopsies help define the disease process and can assist the clinician in forming a prognosis. The small size of liver biopsy specimens and limited responses of the liver to a wide spectrum of injuries often do not allow for a specific etiologic diagnosis. Determination of the distribution and morphology of the lesion often provides useful diagnostic and prognostic information. Maximum value can be attained from liver biopsies when the histologic findings are correlated with the results of other diagnostic tests and there is good communication between the clinician and pathologist.

Animals↗
PubMed1995

Entorhinal inputs to hippocampal CA1 and dentate gyrus in the rat: a current-source-density study.

1. Laminar profiles of the average evoked potentials and current-source-density analysis were used to study the input provided by the medial perforant path (PP) to the hippocampus in the urethan-anesthetized rat. 2. Stimulation of the PP activated an early latency sink in the middle molecular layer of the dentate gyrus (DG) and in the stratum lacunosum-moleculare in CA1. The DG current sink was generated by excitatory synaptic currents activated by the PP on dentate granule cells. In the normal rat, the peak current sink in the DG was typically five times greater than that of CA1. However, the CA1 sink could be distinguished from the DG sink in several ways: 1) it peaked when the DG sink was subsiding; 2) it showed paired-pulse facilitation, whereas the DG sink did not; and 3) in rats in which the DG was lesioned by local colchicine injection, the DG sink was reduced much more than the CA1 sink. 3. The PP afferents to CA1 required a slightly higher stimulus threshold (> 100 microA) for activation than those projecting to the DG granule cells (< 30 microA). The onset latency of the early CA1 sink (2.5 +/- 0.2 ms, mean +/- SE) was also slightly longer than that of the DG sink (1.7 +/- 0.1 ms), suggesting that the axons of entorhinal layer III cells that project to CA1 have a slightly lower conduction velocity than the axons of the layer II cells that project to the DG. 4. The short-latency current sink activated by the PP in the distal dendritic layers of CA1 was likely provided by excitatory currents at the distal apical dendrites of CA1 pyramidal cells. The accompanying current source was mainly confined to stratum radiatum and appeared not to involve the cell body layer. Thus the electrotonic current spread may not be effective enough to depolarize the cell body or axon hillock. Contribution of interneurons to the above source-sink profile is possible, with the provision that these interneurons must have dendritic processes that span strata radiatum and lacunosum moleculare. 5. Extracellular field recordings provided no evidence that PP evoked a short-latency (< 9 ms) CA1-generated population spike, even with the use of micropipettes filled with mM bicuculline. Similarly, unit recordings in CA1 revealed only long-latency (9-17 ms) unit firing after PP stimulation, corresponding to a late, di/trisynaptic excitation of CA1 via the Schaffer collaterals.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Methylphenidate-induced hepatotoxicity in mice and its potentiation by beta-adrenergic agonist drugs.

Methylphenidate hydrochloride, when administered as a single 75 to 100 mg/kg i.p. dose, was found to produce hepatic necrosis in male ICR mice. Peak hepatotoxicity, as measured by serum ALT elevations, occurred 16 hours post-treatment while maximal histopathological evidence of hepatotoxicity occurred 24-48 hours after the methylphenidate dose. Liver injury measured by either method was essentially nonexistent for dosages < or = 50 mg/kg in male mice, and was only minimally evident in female mice at the highest dosage testable. Co-treatment of mice with either alpha 1- or alpha 2-adrenergic agonist drugs had no meaningful effect on methylphenidate-induced hepatotoxicity. In contrast, the beta-adrenergic agonist drug isoproterenol produced a striking potentiation of the liver injury, and shifted the apparent threshold for toxicity approximately 5- to 10-fold. Co-administration of methylphenidate with the mixed alpha/beta-adrenergic agonist dobutamine or with the beta 2-selective agonists metaproterenol, ritodrine or terbutaline produced a similar potentiation of toxicity. Parallel tests with beta-adrenergic antagonists revealed that the potentiation by isoproterenol could be significantly diminished by a single dose of the non-selective beta-adrenoreceptor blocking drug nadolol or the beta 2-selective antagonist ICI-118,551, but not the beta 1-selective antagonist metoprolol. Collectively, these observations suggest that potentiation of methylphenidate hepatotoxicity occurs through stimulation of beta 2-adrenoreceptors. Mice co-treated with isoproterenol were found to have substantially higher serum and liver methylphenidate levels following the methylphenidate dose, and significant increases were also observed in the area-under-the-curve (AUC) for methylphenidate in both tissues of isoproterenol co-treated mice. The results of this study suggest that beta 2-adrenergic agonist drugs are capable of potentiating methylphenidate-induced hepatotoxicity in mice by increasing hepatic methylphenidate concentrations.

Adrenergic alpha-Agonists↗
PubMed1994

A neural network approach to the prediction of pure tone thresholds with distortion product emissions.

Distortion Product Emission (DPE) growth functions, demographic data, and pure tone thresholds were recorded in 229 normal-hearing and hearing-impaired ears. Half of the data set (115 ears) was used to train a set of neural networks to map DPE and demographic features to pure tone thresholds at six frequencies in the audiometric range. The six networks developed from this training process were then used to predict pure tone thresholds in the remaining 114-ear data set. When normal pure tone threshold was defined as a threshold less than 20 dB HL, frequency-specific prediction accuracy varied from 57% (correct classification of hearing impairment at 1025 Hz) to 100% (correct classification of hearing impairment at 2050 Hz). Overall prediction accuracy was 90% for impaired pure tone thresholds and 80% for normal pure tone thresholds. This neural network approach was found to be more accurate than discriminant analysis in the prediction of pure tone thresholds. It is concluded that a general strategy exists whereby DPE measures can accurately categorize pure tone thresholds as normal or impaired in large populations of ears with purely cochlear hearing dysfunction.

Adolescent↗
PubMed1994

Fracture resistance of teeth with bonded amalgams.

Breaking strength of the cusps of molars with MOD amalgam and composite restorations was measured with an Instron. Bonding of the amalgam and composite restorations with adhesives increased the resistance of the cusps to fracture, however, the cusp strength was not returned to that of intact, unprepared teeth. The relative effectiveness of the bonding agents with amalgam was C&B Metabond > Amalgambond > Panavia EX. Reinforcement by amalgam bonding was similar to or less than reinforcement with the composite restorations depending on the adhesive used.

Analysis of Variance↗
PubMed1993

Patient, family, and staff perceptions of coercion in mental hospital admission: an exploratory study.

Little is known about the coercive pressures brought to bear on psychiatric patients in the hospitalization process. Significant methodological hurdles stand in the way of this research. Most notably, reliable and valid methods of ascertaining and quantifying perceptions of coercion have not been developed. This report summarizes the findings of an exploratory study designed to gather data needed to refine the conceptualization and measurement of coercion. Multiple perspectives on admission incidents for forty-three patients (26% of whom were involuntarily hospitalized) were obtained. Patients were administered research interviews and completed a self-administered inventory shortly after the admission decision. The admitting clinician and a family member involved in the admission were administered parallel interviews. In addition, focus groups comprised of outpatients, former patients, family members, and clinical staff were conducted to uncover the terminology and description of coercion commonly used. The implications of these preliminary quantitative and qualitative findings for future research are discussed.

Adult↗
PubMed1992

Cocaethylene hepatotoxicity in mice.

Cocaethylene is a novel metabolite of cocaine formed in the presence of ethanol. When administered to ICR male mice in dosages ranging from 10 to 50 mg/kg, i.p., cocaethylene was found to produce dose-dependent hepatic necrosis in the midlobular zone (zone 2). Severity of the lesion was maximal 12-24 hr after administration. A transient but significant decrease in hepatic glutathione content was observed 1 hr after cocaethylene administration. Pretreatment with the cytochrome P450 inhibitors cimetidine (200 mg/kg, i.p., in divided doses) or SKF 525A (50 mg/kg, i.p.) diminished toxicity. Pretreatment of mice with the esterase inhibitor diazinon (10 mg/kg, i.p.) increased cocaethylene hepatotoxicity, as did pretreatment with the cytochrome P450 inducing agents phenobarbital (80 mg/kg/day, i.p., for 3 days) or beta-naphthoflavone (40 mg/kg/day, i.p., for 3 days). Phenobarbital pretreatment also caused a shift in the morphologic site of necrosis from midzonal to peripheral lobular (zone 1) regions. The type of hepatic lesion produced by cocaethylene, its morphologic distribution (including the shift with phenobarbital treatment), the potency of cocaethylene in producing this effect, and the apparent requirement of oxidative metabolism for hepatoxicity were all remarkably similar to observations with its parent compound, cocaine, in this and earlier studies. This suggests that these compounds produce liver toxicity through the same or similar mechanisms.

Alanine Transaminase↗
PubMed1992

Cocaine hepatotoxicity: influence of hepatic enzyme inducing and inhibiting agents on the site of necrosis.

Cocaine-induced hepatotoxicity has been reported in human beings and is well documented in mice. One interesting feature of this toxicity that appears to be common to both species is an apparent shift in the intraacinar site of necrosis under circumstances known to alter cocaine metabolism. However, the evidence in human subjects is limited, and studies elucidating the mechanism of this phenomenon cannot be performed in human beings. Although future studies in mice may define the basis of this mechanism, the current evidence is a somewhat fragmented composite of studies using different mouse strains and enzyme-inducing agents. Therefore a comprehensive pathologic investigation was initiated for the purpose of identifying and establishing an animal model suitable for studying this phenomenon. In naive ICR mice a single 60 mg/kg dose of cocaine was found to produce midzonal (zone 2) coagulative necrosis. In mice whose oxidative metabolism had been increased with beta-ionone or in which esterase metabolism had been inhibited by diazinon, the severity of the toxicity was increased but the intraacinar origin of the lesion did not change. However, when the oxidative microsomal metabolism of ICR mice was induced by phenobarbital or beta-naphthoflavone, the acinar zone affected was dramatically different. Phenobarbital induction produced zone 1 necrosis, whereas beta-napthoflavone induction caused necrosis in zone 3. The site of necrosis corresponded with the distribution of cocaine, and its metabolites were identified with colloidal gold-conjugated antibody probes. The results of this study suggest that the agents shifting the location of cocaine-induced hepatic necrosis alter the intraacinar site of protein binding of cocaine and its metabolites.

Alanine Transaminase↗
PubMed1992

Use of the Revised Developmental Test of Visual-Motor Integration with chronic mentally ill adult population.

From the Nova University Geriatric Institute, for 30 outpatients ranging in age from 55 to 80 years old, significant moderate Pearson correlations (.40 to .54) obtained between the raw scores of the Revised Developmental Test of Visual-motor Integration standardized for children ages 2 1/2 years through 19 years and the WAIS-R subscale IQs. Further, scores on the Recall administration of the Benton Revised Visual Retention Test were significantly correlated with the performance on Beery's developmental test. Also, scores on Beery's test were correlated with estimates of adaptive functioning made by the staff for each patient.

Aged↗
PubMed1991

Pulmonary hamartoma in a calf.

A pulmonary hamartoma was found in a 5 weeks over term Jersey Holstein cross bull calf. A 36 x 22 x 22 cm, spongy, pale pink mass with a distinct lobulated pattern was continuous with the left caudal lung lobe and compromised other thoracic viscera. The mass was non-cystic and uniformly consisted of soft, pink tissue. Histologically, the mass consisted of a disproportionate number of bronchiolar and alveolar structures, arranged in a haphazard pattern. Ascites, localized subcutaneous oedema, and chronic passive congestion of the liver were additional findings.

Animals↗
PubMed1991

Traumatic reticulitis in cattle: a review of 60 fatal cases.

Sixty fatal cases of traumatic reticulitis in cattle were reviewed. Fifty-nine cases were caused by fragments of wire. A nail perforated the reticulum of 1 animal. Common clinical signs included decreased milk production, anorexia, fever, and weight loss. Abnormal or muffled heart sounds associated with pericarditis and epicarditis was the most common sequela, occurring in 40 cases. Fibrous adhesions found at necropsy in all cases suggest that initial clinical signs are difficult to recognize and in most cases it takes weeks to months for abnormalities to be observed.

Animals↗
PubMed1991

Hepatic lesions in woodchucks (Marmota monax) seronegative for woodchuck hepatitis virus.

Livers from 128 captive woodchucks (Marmota monax) that were negative for serological markers of woodchuck hepatitis virus (WHV) were examined grossly and histologically. Livers from 19 additional seronegative woodchucks were examined only grossly. The most common finding (61% of histological specimens) was mononuclear cells in portal areas. Moderate to severe portal infiltrates in association with similar scattered mononuclear cell aggregates and extramedullary hematopoiesis, were present in woodchucks that had extrahepatic inflammatory lesions. We concluded that these changes represent a response to a variety of chronic infections and are not specific for WHV infection. Other findings included parasitic granulomas, focal and diffuse lipidosis, bile duct proliferation, lesions secondary to cardiovascular compromise, and vasculitis. Two woodchucks had neoplastic lesions.

Animals↗