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Biomedical subjects

C R Katholi

Publications and source records attributed to C R Katholi.

At least 19 recordsLinked to original sources
PubMed1995

Determining the prevalence of Onchocerca volvulus infection in vector populations by polymerase chain reaction screening of pools of black flies.

An important variable in the epidemiology of arthropodborne diseases is the intensity of transmission, which is a function of host-vector contact and the prevalence of infection in the vector population. This latter value is often difficult to estimate. It is possible to envision the application of polymerase chain reaction (PCR) assays to this problem. To accomplish this, the assay must detect a single infected vector in a pool containing a large number of uninfected individuals. It must also be possible to calculate the prevalence of infection from the number of positive pools. A PCR assay for detecting Onchocerca volvulus in pools of vector black flies is described, and an algorithm is presented to calculate the prevalence of infection in the vector population, based upon the proportion of PCR-positive pools. This algorithm should be applicable to any disease for which a PCR assay is available.

Algorithms↗
PubMed1995

Nephrotoxicity from contrast media: attenuation with theophylline.

PURPOSE: To determine if depression of creatinine clearance after administration of contrast medium may be prevented with theophylline. MATERIALS AND METHODS: A nonionic, low-osmolality contrast medium (iopamidol) or an ionic, high-osmolality contrast medium (sodium diatrizoate) was administered to 93 patients. Before the examination, these patients were given theophylline or a placebo orally. There were also 30 patients who received an adenosine-uptake inhibitor (dipyridamole). Creatinine clearance and urinary adenosine levels were measured before and after angiography. RESULTS: Creatinine clearance decreased 18% +/- 4 in the placebo-iopamidol group but did not decrease in the theophylline group; urinary adenosine increased 67% +/- 7. Creatinine clearance decreased 42% +/- 5 in the placebo-sodium diatrizoate group and decreased 24% +/- 3 in the theophylline group; urinary adenosine increased 119% +/- 8. In the dipyridamole group in which iopamidol was given, urinary adenosine increased 96% +/- 7 and creatinine clearance decreased 37% +/- 5. CONCLUSION: Intrarenal adenosine can be implicated in the pathogenesis of hypertonic contrast medium nephrotoxicity.

Adenosine↗
PubMed1995

Functional deficits in autistic disorder: characterization by technetium-99m-HMPAO and SPECT.

UNLABELLED: Autistic disorder is an early and severe developmental disorder characterized by deficits in verbal and nonverbal language, social skills, cognitive functioning and an abnormal repertoire of behaviors. Current research, however, has failed to identify the neurobiological mechanisms that underlie autism or those cortical brain regions, if any, that are abnormal. METHODS: We examined regional cerebral blood flow (rCBF) in six young, severely autistic patients. High-resolution brain SPECT with 99mTc-HMPAO was performed while five of the six patients were under general anesthesia. The scans reflected the subjects' rCBF in their usual alert behavioral state, since the tracer was injected at least 15 min prior to anesthesia and is rapidly extracted and fixed in the brain. A computer-automated cortical region of interest (ROI) generator was used to define 12 annular cortical regions (region 1 = left frontal, clockwise to region 12 = right frontal) for count data acquisition. The ratio of average counts in each ROI to whole-slice counts for the autistic patients was compared to age-matched controls using repeated measures (splt-plot) ANOVA statistical analysis for three representative brain levels. RESULTS: In the autistic patients, cortical regions 3, 4, and 10 were abnormally low at the cortical level canthomeatal (CM) + 3.5 cm. At level CM + 5.5 cm, regions 3, 4, 5 and 10 were abnormally low, and at level CM + 7.5 cm, regions 7 and 9 were also abnormally low. These regions correspond to abnormally low rCBF values located predominately in the temporal and parietal lobes, with the left cerebral hemisphere showing greater rCBF abnormalities than the right. CONCLUSION: Our findings suggest that the temporal and parietal lobes have abnormal rCBF in autism. HMPAO brain SPECT in combination with general anesthesia is particularly useful for imaging severely noncompliant patients.

Adolescent↗
PubMed1994

Issues in meta-analysis: an overview.

A summary is provided for the relevant issues that investigators must address when wishing to synthesize data via a meta-analysis. The analogy is made to conducting a clinical trial and its components. Both design and statistical issues are discussed with the goal of assuring that the proper elements are included in the meta-analysis. Further, global concerns are presented so that the researcher is aware of the clinical controversies faced when conducting a meta-analysis. Finally a comparison is made of the advantages and disadvantages of a large-scale clinical trial versus a meta-analysis.

Clinical Trials as Topic↗
PubMed1994

Recent evolutionary history of American Onchocerca volvulus, based on analysis of a tandemly repeated DNA sequence family.

Polymerase chain reaction (PCR) products were characterized for a repeated sequence family (designated "O-150") of the human filarial parasite Onchocerca volvulus. In phylogenetic inferences, the O-150 sequences clustered into closely related groups, suggesting that concerted evolution maintains sequence homology in this family. Using a novel mathematical model based on a nested application of an analysis of variance, we demonstrated that African rainforest and savannah strain parasite populations are significantly different. In contrast, parasites collected in the New World are indistinguishable from African savannah strains of O. volvulus. This finding supports the hypothesis that onchocerciasis was recently introduced into the New World, possibly as a result of the slave trade.

Americas↗
PubMed1994

DNA sequence analysis using hierarchical ART-based Classification Networks.

Adaptive resonance theory (ART) describes a class of artificial neural network architectures that act as classification tools which self-organize, work in realtime, and require no retraining to classify novel sequences. We have adapted ART networks to provide support to scientists attempting to categorize tandem repeat DNA fragments from Onchocerca volvulus. In this approach, sequences of DNA fragments are presented to multiple ART-based networks which are linked together into two (or more) tiers; the first provides coarse sequence classification while the subsequent tiers refine the classifications as needed. The overall rating of the resulting classification of fragments is measured using statistical techniques based on those introduced by Zimmerman, et al. (1994) to validate results from traditional phylogenetic analysis. Tests of the Hierarchical ART-based Classification Network, or HABclass network, indicate its value as a fast, easy-to-use classification tool which adapts to new data without retraining on previously classified data.

Algorithms↗
PubMed1993

Nephrotoxicity of nonionic low-osmolality versus ionic high-osmolality contrast media: a prospective double-blind randomized comparison in human beings.

To test whether a nonionic, low-osmolality contrast medium (iopamidol) administered for coronary angiography was less harmful to renal function than ionic, high-osmolality medium (sodium diatrizoate), a prospective, double-blind randomized study of 70 patients with normal or mildly depressed renal function (serum creatinine < or = 2.0 mg/dL (175 mumol/L) was performed. Creatinine clearance was determined before coronary angiography and 24 and 48 hours after. There were no significant differences between the low- and high-osmolality groups with regard to age, baseline creatinine clearance, or dose of contrast medium given. In patients receiving low-osmolality medium (n = 35), creatinine clearance decreased by 19% +/- 13 (1 standard deviation) at 24 hours and recovered by 48 hours. In patients receiving high-osmolality medium (n = 35), creatinine clearance decreased by 40% +/- 16 at 24 hours and remained depressed by 47% +/- 14 at 48 hours. In patients with normal or mildly depressed renal function, use of a non-ionic, low-osmolality contrast medium minimized nephrotoxicity as measured by reductions in creatinine clearance after coronary angiography.

Adolescent↗
PubMed1987

Morphology of occlusive coronary lesions during acute myocardial infarction: an angiographic and clinical analysis.

In an attempt to identify angiographic and clinical predictors of reperfusion, 42 patients who received intracoronary streptokinase during the early phase of myocardial infarction were analyzed. The different morphologies (regular and irregular) of the occlusive lesions did not show a significant relation with the response (reperfusion vs nonreperfusion) to intracoronary streptokinase; neither did the presence of angiographically visualized thrombus in the infarct-related artery favor reperfusion. Among the clinical variables analyzed (previous myocardial infarction, previous angina, diabetes mellitus, hypertension, use of tobacco, and hyperlipidemia), a history of previous angina was significantly related to absence of reperfusion (p = 0.001). Although the presence of thrombus showed a trend toward reperfusion (p = 0.1), overall, our angiographic observations did not contribute to predicting the response to streptokinase. Further studies are needed to identify morphologic criteria favoring reperfusion and select groups of patients most likely to benefit from it.

Adult↗
PubMed1987

Focal right temporo-occipital blood flow changes associated with judgment of line orientation.

Focal cerebral blood flow changes for judgment of line orientation were determined using the 133Xe inhalation technique with 18 normal right-handed male subjects. Measurements were made during three conditions in the same session: a line orientation task, a sensorimotor control task, and normal rest. Blood flow changes attributable to the judgment of line orientation were found for the measure f1 at a detector centered over the right temporo-occipital region. For the measure IS this activation was significant in the temporo-occipital region in both hemispheres but significantly greater in the right hemisphere. For f1 the change in blood flow and for IS the percent change in blood flow in the right temporo-occipital region attributable to judgment of line orientation decreased as performance on the line orientation task improved.

Adolescent↗
PubMed1986

Length and circumference measurements in one-joint and multijoint muscles in rabbits after immobilization.

In this article, we compared changes in the length and circumference of the soleus and the plantaris muscles in rabbits. The rabbits were assigned to a nonimmobilized external control group (n = 4), an experimental shortened-position group (n = 10), or an experimental lengthened-position group (n = 9). One hind limb of each animal in the experimental groups was immobilized in a cast for four weeks to put the muscles in either a shortened or lengthened position. The contralateral limb served as an internal control for the animals in the experimental groups. After the immobilization period, the limbs were fixed in situ, the muscles were dissected, and length and circumference measurements were taken. In both experimental conditions, the immobilized soleus muscles were shorter than their contralateral counterparts (p less than .05); the length of the plantaris muscles did not change. The immobilized muscles had decreased circumference values regardless of the immobilization angle. When compared with the control condition, the shortened soleus muscles had a greater decrease in circumference than did the plantaris muscles. More connective tissue was observed in the muscle bellies of the soleus after immobilization than in the plantaris. Similar significant changes (p less than .05) were found in the nonimmobilized limbs of the animals in the experimental groups. Specifically, the soleus muscles demonstrated length and circumference changes, whereas the plantaris muscles showed changes only in circumference. These findings suggest that when a weight-bearing limb is immobilized, adaptations in gross muscle length and circumference are to be expected in the involved and uninvolved limbs. An assessment of similar adaptations in humans should be a part of the evaluation during recovery.

Analysis of Variance↗
PubMed1985

Age differences in cerebral blood flow during rest and during mental activation measurements with and without monetary incentive.

This experiment compared the diffuse and regional cerebral blood flow (CBF) during rest and during cognitive activation with and without incentive-induced arousal in young, middle-aged, and older adults. Two normal rest CBF measurements were followed by two mental mathematics activation CBF measurements. For the first activation measurement, half the participants in each age group were offered monetary incentive for correct performance and half the participants received no monetary incentive. All participants were offered monetary incentive on the final activation measurement. Older participants had lower resting blood flow at all detectors, but age-related reductions in blood flow were statistically significant only in anterior and inferior rolandic regions. The effect of monetary incentive was to increase blood flow at the inferior rolandic detector in both hemispheres. The CBF response to cognitive activation and monetary incentive did not differ in the three age groups.

Adult↗
PubMed1985

Direct relationship between high-energy phosphate content and blood flow in thermally treated murine tumors.

In vivo 31P-nuclear magnetic resonance (NMR) spectroscopy and 133Xe clearance were used to monitor serially ATP content and blood flow, respectively, in C3H/HeJ mouse subcutaneous RIF-1 tumors treated with hyperthermia. There was a prompt decrease in ATP [measured spectroscopically and expressed as the ratio of ATP to Pi (ATP/Pi)]. The slope and magnitude of the change in ATP closely paralleled those of tumor blood flow. Close correlation between these two variables was seen when data were analyzed both by treatment group and by individual mouse. Ligated tumors showed qualitatively and quantitatively similar changes in ATP/Pi and blood flow. RIF-1 cells heated in vitro to a similar degree showed no decrease in ATP. The loss of ATP in subcutaneous RIF-1 tumors heated in vivo was primarily due to disruption of tumor blood flow. These data emphasize the importance of vascular factors to in vivo thermal effects. In vivo 31P-NMR spectroscopy can be used to monitor indirectly vascular effects from hyperthermia.

Adenosine Triphosphate↗
PubMed1984

Relevance of sensorimotor task components to the interpretation of task related blood flow changes.

This study demonstrated the importance of documenting rCBF changes produced by the sensorimotor components of a cognitive task when making inferences regarding brain-behavior relations. Subjects were ten young, non-smoking adult, right-handed, normal male volunteers. They were administered two tasks having identical cognitive and similar sensory components but different response modalities (oral vs manual). The two tasks produced highly divergent rCBF landscapes. In conjunction with the results from a previous rCBF activation study, these data were used to illustrate the necessity of including sensorimotor control tasks in cognitive activation studies designed to elucidate brain-behavior relations.

Adult↗
PubMed1984

Focal changes in cerebral blood flow produced by monetary incentive during a mental mathematics task in normal and depressed subjects.

The purpose of this experiment was to determine the effect of incentive-induced arousal on the diffuse and regional cerebral blood flow (rCBF) response during cognitive activation for normal and depressed groups. Two normal rest CBF measurements were followed by two mental mathematics activation CBF measurements. For the first activation measurement, half the subjects in each group were offered monetary incentive for correct performance and half the subjects received no monetary incentive. All subjects were offered monetary incentive on the final activation run. The effect of monetary incentive on the first activation run was to increase CBF activation at four detectors in the left hemisphere. Incentive did not affect the CBF activation response when introduced following practice on the activation task (on the final run). Depressed groups had lower resting blood flow than normals, but the distribution of flow and the CBF response to incentive were almost identical in the two groups.

Adult↗
PubMed1984

Loss of high-energy phosphate following hyperthermia demonstrated by in vivo 31P-nuclear magnetic resonance spectroscopy.

We have used in vivo 31P-nuclear magnetic resonance spectroscopy to study the changes in high-energy phosphates following hyperthermia. Immediately after heating, there is a fall in adenosine triphosphate and apparent intracellular pH and an increase in inorganic phosphate. Following sublethal heating (40 degrees for 15 min), these changes were partial, and they resolved over the subsequent 45 hr. With tumors given severe hyperthermia (47 degrees for 15 min), there was complete disappearance of adenosine triphosphate, with no recovery by 24 hr posttreatment. Qualitatively similar effects were seen after heating of normal leg muscle. The degree of fall of the adenosine triphosphate/inorganic phosphate concentration ratio was directly proportional to the heat dose and to thermal cell kill. 31P-Nuclear magnetic resonance spectroscopy may be useful in thermal dosimetry and treatment evaluation following hyperthermia.

Animals↗
PubMed1983

Age effects on focal cerebral blood flow changes produced by a test of right-left discrimination.

The effects of age on focal cerebral blood flow changes resulting from the cognitive processing during right-left discrimination were examined. The pattern and amount of cortical flow were comparable for young and middle-aged subjects and consisted of flow increases in bilateral frontal, parietal and occipital regions. Task performance was negatively related to activation from left parietal and occipital channels. The frontal activation and the parietal correlation were attributed to the middle-aged subjects experiencing increased emotional arousal and attention to the right-left discrimination task due to hypothesized differences in cognitive effort and style, and/or novelty of formal examination situations.

Adult↗
PubMed1983

rCBF for middle-aged males and females during right-left discrimination.

rCBF was measured in 10 male and 10 female normal righthanders with an average age of 44.2 years. For the measures f1 and IS significant occipital lobe activation was produced bilaterally and for the measure IS significant left hemisphere parietal activation was produced also by a visually presented right-left discrimination cognitive activation task over and above the activation produced by a sensorimotor control task. The amount and pattern of blood flow changes were similar for both sexes. Performance of males on the cognitive task was not significantly better than that of females. However, an inverse relationship was found for males but not females between cognitive task performance and percentage increase in IS for all regions showing significant cognitive activation.

Adult↗