Biomedical subjects
S Hussain
Publications and source records attributed to S Hussain.
GABA and glutamate levels in the substantia nigra reticulata following repetitive cerebral ischemia in gerbils.
Repetitive cerebral ischemia produces more severe damage than a similar single duration insult. We have previously shown that, in gerbils, damage in the substantia nigra reticulata (SNr) is seen with repetitive insults rather than a single insult. We have also shown that there is a progressive decrease in the extracellular GABA in the striatum in the days preceding such damage, speculating that a loss of GABA may be in part responsible for this damage. This study evaluates the GABA levels in the SNr in animals exposed to repetitive ischemic insults. Each animal received a total of three ischemic insults of 3-min duration at hourly intervals. In vivo microdialysis was carried out to analyze the GABA and glutamate dialysate levels on Days 1, 3, 5, 7, and 14 following the ischemic insult. In the control and treated (ischemic) animals, there was a significant increase in the GABA levels with the introduction of nipecotic acid on Days 1, 3, 5, and 14. However, on Day 7 there was a significant attenuation in the GABA response to nipecotic acid in the treated animals in comparison to the controls. The glutamate levels in the treated animals were similar to the control animals on Days 1, 3, 5, and 7. However, on Day 14 the glutamate levels were significantly lower than on previous days. Our experiments for the first time measure extracellular glutamate and GABA responses in the SNr in animals exposed to repetitive ischemic insults. Our experiments show that there is a significant decrease in the GABA concentrations at a time when ischemic damage is developing in this region. This confirms our hypothesis that a decrease in GABA may be one factor contributing to neuronal damage during the period following repetitive ischemic insults. Further, the rebound increase in GABA levels on Day 14 with a concomitant fall in glutamate levels would indicate that reparative processes are still active in the 2 weeks following the insult.
Thin-section helical computed tomography of the bladder: initial clinical experience with virtual reality imaging.
OBJECTIVES: To evaluate the application of virtual reality imaging of the bladder (virtual cystoscopy) in the detection of bladder masses. METHODS: Six patients (mean age 61 years, range 43 to 75) with hematuria and positive findings on conventional cystoscopy were studied by means of thin-section helical computed tomography of the air-distended bladder. Using volume-rendering algorithms, interactive intraluminal views of the bladder mucosa were generated (virtual cystoscopy). Results of virtual cystoscopy were compared with those of conventional cystoscopy in each case. RESULTS: Twenty-six (100%) of 26 masses (mean size 1.7 cm, range 0.3 to 6), detected on conventional cystoscopy, were visualized on virtual cystoscopy. Twelve of 26 masses measured less than 1 cm in maximum diameter. All masses were pathologically proven transitional cell carcinomas. Virtual cystoscopy was well tolerated by all patients, and no complications occurred. CONCLUSIONS: Our results indicate that virtual cystoscopy is an accurate technique for detection of intrinsic bladder masses. It may represent a radiologic adjunct to conventional cystoscopy for initial evaluation of patients with hematuria and for surveillance of patients after bladder tumor resection.
Ultrasound guided percutaneous galactography.
We present a new percutaneous ultrasound-guided galactography technique that can be used in patients in whom there is no access to the milk duct at the nipple.
Mercuric chloride-induced reactive oxygen species and its effect on antioxidant enzymes in different regions of rat brain.
The present study was undertaken to determine if in vitro exposure to mercuric chloride produces reactive oxygen species (ROS) in the synaptosomes prepared from various regions of rat brain. The effects of in vivo exposure to mercury on antioxidant enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities in different regions of rat brain were also investigated. Adult male Sprague-Dawley (CD) rats were dosed with 0, 1, 2.0 or 4.0 mg HgCl2/kg body weight, for 7 days. One week after the last dose, animals were sacrificed by decapitation, their brains were removed and dissected and frozen in dry ice prior to measuring the activities of these enzymes. The results demonstrated that in vitro exposure to mercury produced a concentration-dependent increase of ROS in different regions of the rat brain. In vivo exposure to mercury produced a significant decrease of total SOD, Cu, Zn-SOD and Mn-SOD activities in the cerebellum of rats treated with different doses of mercury. SOD activity did not vary significantly in cerebral cortex and brain stem. GPx activity declined in a dose-dependent manner in the cerebellum with a significant reduction in animals receiving the 4 mg HgCl2/kg body weight. The activity of GPx increased in the brain stem while unchanged in the cerebral cortex. The results demonstrate that inorganic mercury decreased SOD activity significantly in the cerebellum while GPx activity was affected in both cerebellum and brain stem. Therefore, it can be concluded that oxidative stress may contribute to the development of neurodegenerative disorders caused by mercury intoxication.
Analysis of a straight-line capnographic waveform.
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An STS-based radiation hybrid map of the human genome.
We have constructed a physical map of the human genome by using a panel of 83 whole genome radiation hybrids (the Stanford G3 panel) in conjunction with 10,478 sequence-tagged sites (STSs) derived from random genomic DNA sequences, previously mapped genetic markers, and expressed sequences. Of these STSs, 5049 are framework markers that fall into 1766 high-confidence bins. An additional 945 STSs are indistinguishable in their map location from one or more of the framework markers. These 5994 mapped STSs have an average spacing of 500 kb. An additional 4484 STSs are positioned with respect to the framework markers. Comparison of the orders of markers on this map with orders derived from independent meiotic and YAC STS-content maps indicates that the error rate in defining high-confidence bins is < 5%. Analysis of 322 random cDNAs indicates that the map covers the vast majority of the human genome. This STS-based radiation hybrid map of the human genome brings us one step closer to the goal of a physical map containing 30,000 unique ordered landmarks with an average marker spacing of 100 kb.
Blood splashes to the masks and goggles during caesarean section.
A prospective study was performed of 100 caesarean sections (31 elective, 69 emergency) to determine the incidence of blood splashes to the masks and goggles of surgeons, assistants and scrub nurses. The rate of blood splashes was 40% on surgeons' masks, 49.29% on surgeons' goggles, 31% on assistants' masks, 21.12% on assistants' goggles, 23.1% on scrub nurses' masks and 15.71% on scrub nurses' goggles. The use of masks and protective goggles is strongly recommended to avoid body fluid contamination and acquiring disease in obstetrics.
Virtual cystoscopy: early clinical experience.
Virtual cystoscopy was performed in 13 patients with hematuria and abnormal findings at conventional cystoscopy. Perspective volume-rendering algorithms were applied to helical computed tomographic data to generate interactive, intraluminal views of the bladder mucosa after insufflation of room air. At conventional cystoscopy, 29 masses appeared to arise from the bladder mucosa and two were hypertrophied median lobes of the prostate. At virtual cystoscopy, 30 masses arose from the bladder (one prostate mass was misinterpreted as an intrinsic bladder mass). Results at virtual cystoscopy were comparable to those at conventional cystoscopy but were obtained without the associated risks.
MR urography: evaluation of a three-dimensional fast spin-echo technique in patients with hydronephrosis.
OBJECTIVE: The purpose of this study was to evaluate a respiratory-triggered three-dimensional (3D) fast spin-echo technique for MR urography in patients with urinary tract dilatation. SUBJECTS AND METHODS: Using a respiratory-triggered 3D fast spin-echo technique for MR urography, we obtained MR urograms in 24 patients with hydronephrosis. Images were separately reviewed by two radiologists who evaluated the images for quality, presence of, degree of, level of, and cause of urinary tract dilatation. Findings were compared with all available clinical, imaging, surgical, and pathologic data, which served as the standard of reference. Sensitivity, specificity, positive predictive value, and negative predictive value of MR urograms were calculated for each reviewer to reveal urinary tract dilatation. For each reviewer, we calculated agreement between MR urography and the standard of reference using kappa analysis. We also calculated interobserver agreement for the presence of degree of, level of, and cause of urinary tract dilatation. RESULTS: Technically adequate MR urograms were obtained in all patients. For detection of urinary tract dilatation by MR urography, the sensitivity was 100%; specificity was 96%; positive predictive value was 96%; and negative predictive value was 100%. The kappa values for the degree of dilatation seen on the MR urograms were 0.57 (moderate) and 0.43 (moderate); for the level of obstruction, 0.74 (substantial) and 0.55 (moderate); and for the cause of obstruction, 0.66 (moderate) and 0.66 (moderate). Interobserver agreement for seeing dilatation on MR urograms was 1.0 (perfect agreement); degree of dilatation, 0.48 (moderate); level of dilatation, 0.60 (moderate); and cause of dilatation, 0.74 (substantial). CONCLUSION: MR urography using a respiratory-triggered 3D fast spin-echo technique can produce high-resolution images of the urinary tract by which reviewers can achieve a high sensitivity (100%) and specificity (96%) for the detection of urinary tract dilatation. On MR urograms, reviewers also identified the cause of obstruction in most patients: 92% (reviewer 1) and 88% (reviewer 2).
Non-specific effect of beettahistine on cochlear electrophysiology in guinea pig.
Beettahistine hydrochloride (BH) is reported to be beneficial in the treatment of certain type of vestibulo-cochlear disorders. Experimentally is shown that BH inhibits vestibular firing rate and improves cochlear blood flow by dilatating the larger feeding vessels. Both these effects are weak, and hardly can explain the clinical benefits reported for the drug. We investigated the effect of BH on the organ of Corti electrophysiology in vivo. Two microliters of 1, 2, 5 and 10% saline solutions of BH was applied (in increasing order) to the round window (RW) membrane in an anesthetized guinea pig (n = 5). Summating potential (SP), action potential (AP), and cochlear microphonics (CM) were recorded at 16 kHz frequency using RW Ag wire electrode. The repeated applications of BH with increasing concentrations produced a dose-dependent threshold shift in CAP. The I/O function for 20, 30, 40, 50, 60, 70, and 80 dB at 16 kHz indicated that there was a saturation before complete blockade of the responsiveness in all measured parameters. SP and CM changes nearly followed CAP changes. The changes recover during 2 hours follow-up period. Our findings indicate that BH affects the organ of Corti electrophysiology. That the drug effect saturates before a complete blockade suggests non-specific effect of BH on the organ of Corti structures and cochlear nerve.
How and where the education dollar is spent.
Locally elected school boards have the authority and responsibility to decide how school budgets will be spent. In doing so, however, they must balance multiple funding restrictions and competing priorities. Despite great variance in local circumstances, most school districts have remarkably similar spending patterns, generally allocating from 60% to 63% of their budget to instruction and dividing the remainder among student services such as health services, counseling, and speech therapy; administration; building operation and maintenance; and food services and transportation. Polls show that many districts are attempting to delegate more decisions over resource allocation to the school site level. Research is just beginning to show what aspects of school site decision making are associated with improved teaching and learning.
MR urography.
Developments of MR imaging of static fluid has led to the emergence of MR urography (MRU) as a potential imaging technique of the urinary system. MRU has been shown to be highly sensitive in the diagnosis of urinary obstruction, defining the severity of dilatation, the site, and in the majority of cases, the cause of obstruction. At the current level of resolution, however, MR cannot consistently demonstrate nonobstructive or small obstructing calculi. Demonstration of perinephric and periuretic edema in obstruction helps in the differentiation of acute from nonacute urinary obstruction. MRU has shown potential in the work-up of urinary disease for which intravenous urography used to be performed, without the hazards of intravenous contrast administration.
Dicrotic wave and anthropometry.
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A gene map of the human genome.
The human genome is thought to harbor 50,000 to 100,000 genes, of which about half have been sampled to date in the form of expressed sequence tags. An international consortium was organized to develop and map gene-based sequence tagged site markers on a set of two radiation hybrid panels and a yeast artificial chromosome library. More than 16,000 human genes have been mapped relative to a framework map that contains about 1000 polymorphic genetic markers. The gene map unifies the existing genetic and physical maps with the nucleotide and protein sequence databases in a fashion that should speed the discovery of genes underlying inherited human disease. The integrated resource is available through a site on the World Wide Web at http://www.ncbi.nlm.nih.gov/SCIENCE96/.
Genome maps 7. The human transcript map. Wall chart.
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Role of metallothionein and other antioxidants in scavenging superoxide radicals and their possible role in neuroprotection.
Based on the inhibition of nitrite formation by generating superoxide from xanthine/xanthine oxidase (X/XO) reaction system, metallothionein (MT) and other sulfhydryl containing amino acids have been selected to test their abilities to scavenge superoxide radicals. Different concentrations of metallothionein and other sulfhydryl containing molecules e.g. cysteine, N-acetyl-cysteine and glutathione, were used to assess superoxide scavenging properties. Metallothionein scavenges superoxide radical in a dose-dependent manner with increasing concentrations as evidenced by the inhibition of nitrite formation. Similar abilities to scavenge superoxide radicals were shown by cysteine, N-acetyl-cysteine. Glutathione also scavenges superoxide radical in a dose-dependent manner. In vitro experiments demonstrated that metallothionein is superior in scavenging superoxide radicals compared to other sulfhydryl molecules such as cysteine, N-acetyl-cysteine and even glutathione. The data, further, suggest that metallothionein-II has a 6-fold higher capacity to scavenge superoxide radical than metallothionein-I. In addition, metallothionein-like protein was isolated from different regions of mouse brain treated with zinc. Brain metallothionein-like protein inhibits nitrite formation as demonstrated by other scavengers; however, the extent of inhibition is different by this protein isolated from different brain regions. The present study suggests that metallothioneins and metallothionein-like proteins isolated from mouse brain act as neuroprotective agents by scavenging superoxide radicals.
A longitudinal investigation of duration and temporal variability in children's speech production.
A number of cross-sectional, acoustic studies have found that young children's speech segments tend to be longer and more variable than those of older children and adults. However, very little longitudinal information of this nature is available that considers changes across time for individual children. The present investigation is a longitudinal analysis of several temporal characteristics of the speech of 12 children of various ages who were each seen twice, approximately 1 1/2 years apart. For the group, durations decreased on average from the initial to the follow-up recordings by approximately 10%, and temporal variability decreased by about 40%. For the individual children, however, it was found that some of them showed few, if any, changes in some of the temporal measurements made at the two different times, whereas others showed substantial differences. Younger children also did not necessarily show longer durations or greater variability than older children, nor did younger children always show greater changes across time than older children. Thus, although cross-sectional studies indicate that there is a general tendency when comparing groups for increased age to be associated with shorter durations and reduced variability, individual children may not evidence such patterns or changes across time.