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Biomedical subjects

J Towfighi

Publications and source records attributed to J Towfighi.

At least 55 records · Page 3Linked to original sources
PubMed1993

Effect of anesthetics on neuropathologic sequelae of status epilepticus in rats.

We compared the efficacy of four different classes of anesthetics to arrest the progression of brain damage after chemoconvulsant-induced seizures in rats. In two series of experiments, ventilated, paralyzed Long-Evans rats were subjected to 30 or 45 min of continuous seizures induced by intravenous (IV) mercaptopropionic acid (MPA) or inhaled flurothyl, respectively. In the first series, seizures produced with MPA were treated with: 1) thiopental, 15 mg/kg IV bolus (controls); 2) thiopental, 27 mg/kg IV followed by 20.9 mg.kg-1.h-1 for 2 h; 3) isoflurane 4% inhaled concentration for 1 min followed by 1%-2% for 2 h; 4) ketamine 30 mg/kg IV followed by 9.12 mg.kg-1.h-1 for 2 h; 5) midazolam 25 mg/kg IV followed by 9.7 mg.kg-1.h-1 for 2 h. In a second series, seizures were produced by flurothyl and, based on suggestive results in the MPA series, control rats were compared with rats receiving midazolam 25 mg/kg IV followed by 9.7 mg.kg-1.h-1. In all instances, seizure activity, recorded by electroencephalograph, stopped with anesthetic treatment. In MPA-treated rats extranigral damage was mild, with no differences apparent between anesthetics. Control animals sustained severe lesions in the substantia nigra pars reticulata (SNPR). No statistically significant differences between anesthetic groups were present, although an effect was suggested for midazolam to decrease SNPR lesional area (P = 0.06). In flurothyl-treated rats, there were significant reductions in SNPR neuropathologic grade (P = 0.025) and lesional area (P = 0.025) with midazolam. We conclude that midazolam attenuates postseizure SNPR damage in rats.

3-Mercaptopropionic Acid↗
PubMed1992

Early onset autosomal dominant progressive muscular dystrophy presenting in childhood as a Becker phenotype--the importance of dystrophin and molecular genetic analysis.

We present two cases of autosomal dominant limb girdle muscular dystrophy in a father and son. Both presented in childhood with a classical Becker muscular dystrophy phenotype. The father had initially been informed that he would not have affected children. After the diagnosis of muscular dystrophy in the son, immunoblot analysis was performed on muscle and revealed normal dystrophin. The polymerase chain reaction did not show any deletions in the dystrophin gene, and the father's dystrophin gene was not passed to his son. These cases demonstrate that autosomal dominant muscular dystrophy may present in childhood, and that dystrophin and molecular genetic analyses should be performed when considering the diagnosis of childhood muscular dystrophy, even in the presence of a classical phenotype.

Child↗
PubMed1992

Effect of insulin-induced and fasting hypoglycemia on perinatal hypoxic-ischemic brain damage.

Experiments in adult animals have indicated that hyperglycemia accentuates whereas hypoglycemia ameliorates hypoxic-ischemic brain damage. To determine whether hypoglycemia is protective or deleterious to the perinatal brain subjected to hypoxia-ischemia, 7-d postnatal rats were rendered hypoglycemic either by receiving an s.c. injection of insulin or fasting for 12 h. All rat pups underwent unilateral common carotid artery ligation followed by exposure to 8% oxygen-balance nitrogen at 37 degrees C for 2 h. Control animals (no insulin or fasting) received s.c. injections of normal saline. Mean blood glucose concentrations were 5.4 +/- 0.1, 4.3 +/- 0.2, and 3.4 +/- 0.1 mmol/L for control, insulin, and fasted animals, respectively. Blood beta-hydroxybutyrate concentrations were identical (0.5 +/- 0.1 mmol/L) for control and insulin-treated animals, but more than doubled in concentration in the fasted animals (p less than 0.001). Mortality rates during hypoxia-ischemia were higher in the insulin-treated animals (30%) than in either the fasted (4%) or control (0%) animals (p less than 0.05). Fasted animals showed a significant reduction in hypoxic-ischemic brain damage as compared with either the insulin-treated or control animals. Insulin-treated animals were not significantly different from controls. The findings indicate that 1) insulin induced hypoglycemia does not provide a protective effect on perinatal hypoxic-ischemic brain damage, as in adults; and 2) fasting adequate to produce hypoglycemia and ketonemia improved neuropathologic outcome.

Animals↗
PubMed1991

Spinal cord abnormalities in caudal regression syndrome.

Caudal regression syndrome includes malformations ranging from mild forms of sacral agenesis to severe limb anomalies referred to as sirenomelia. The latter, in addition to sacral anomalies, shows malformed single lower limb and agenesis of rectum and genitourinary tracts. We report the neuropathologic examination in four infants, three with sirenomelia and one with lumbosacral agenesis. Brain and spinal cord were normal except for the structures in the caudal region of the spinal cord that were abnormal in all four cases. The first sirenomelic case with a mild sacral hypoplasia had only minor fusion of a few sacral roots and a slightly low-positioned conus medullaris. The second sirenomelic case with an intermediate degree of sacral hypoplasia had fusion of some of the sacral roots and ganglia, spinal ganglion cell heterotopias, filar lipoma and absence of the last sacral roots and ganglia. The third sirenomelic case with a severe degree of sacral hypoplasia showed additional tethering of the spinal cord. Case four with the agenesis of the lumbosacral spine had a total lack of the lumbosacral spinal cord, and dysplasia of the T11 and T12 cord segments. These findings suggest that the extent of anomalies of the caudal spinal cord structures in the caudal regression syndrome are roughly proportional to the anomalies of the vertebral column, and that they may constitute some of the main components of this syndrome.

Abnormalities, Multiple↗
PubMed1991

Cerebro-ocular dysplasia--muscular dystrophy (Walker Warburg) syndrome. Findings in 20-week-old fetus.

A 20-week fetus affected with cerebro-ocular dysplasia and muscular dystrophy (Walker-Warburg Syndrome) is reported. The central nervous system (CNS) findings were typical of those previously described in this disorder, and were characterized by lissencephaly, hydrocephalus, and cerebral and cerebellar cortical dysplasia with glial and neuronal displacement into the leptomeninges. In addition, severe hypoplasia of pyramidal tracts were noted in the brain stem and spinal cord, as well as malformation of the inferior olivary and dentate nuclei. Skeletal muscle and eyes appeared normal on light microscopy. The genetic defect in this disorder is expressed in the CNS early during the first trimester and causes a marked disorder of cellular migration. Overt changes in muscle occur during a later period. The changes in the CNS are similar to, but more severe than, those found in Fukuyama congenital muscular dystrophy, and both may represent a failure of constraint of neuronal migration. Whether the syndromes characterized by cerebro-ocular dysplasia and muscular dystrophy are genetically heterogeneous or allelic variations is unknown. Molecular genetic analysis should elucidate this question.

Brain↗
PubMed1991

Neuropathology of remote hypoxic-ischemic damage in the immature rat.

This study was undertaken to determine: (a) the duration of hypoxia required to produce brain damage in immature rats with unilateral carotid artery ligation (Levine technique); (b) the regions of immature brain most vulnerable to hypoxia-ischemia (HI); and (c) the neuropathology of the remote HI insult. To this end, 7-day postnatal rats, subjected to unilateral carotid artery ligation combined with hypoxia of varying durations (45, 60, 75 or 90 min), were killed at 30 days of postnatal age and their brains examined by light microscopy. The results indicated that a longer duration of HI was more likely to produce brain lesions and that the extent and severity of the lesions closely correlated with the length of HI. Shorter intervals of HI primarily damaged the cerebral cortex and hippocampus, while longer periods resulted in more extensive damage and were often associated with cavitary lesions of the cerebral hemisphere. Comparison of HI brain damage produced by the Levine technique in immature and adult rats suggested that in immature rats: (a) the cavitary lesions were common; (b) the non-cavitary cortical lesions had a tendency to show a vertical band-like distribution - a pattern never seen in adults; and (c) the lesions often showed mineralization. The similarities between these experimentally produced HI cerebral lesions and those observed in the developing human brain, such as ulegyria and porencephaly, are discussed.

Amygdala↗
PubMed1991

Brain energy consumption in ethanol-treated, Long-Evans rats.

The cerebral metabolic rate of glucose utilization (CMRGlc) was measured in rats fed liquid diets containing ethanol for 8 wk, after removal of ethanol from the diet and after acute ethanol intoxication. Control rats were pair fed the liquid diets containing isoenergetic amounts of dextrin-maltose. Quantitative autogradiography using [6-14C]glucose measured CMRGlc at the level of individual structures. Digital image techniques created stereograms of brain energy consumption from the autoradiographs. These techniques provided information about CMRGlc throughout the brain. Rats given the ethanol liquid diet drank constantly throughout the day and night. Neuropathological examination of brain revealed no abnormalities from ethanol consumption. Acute ethanol administration to control rats produced a decrease in CMRGlc throughout the brain that was most prominent in structures concerning auditory, visual, memory and motor functions. Chronic ethanol consumption did not reduce CMRGlc to the same degree as acute ethanol intoxication; in fact, it affected only a few structures. The removal of ethanol from chronic ethanol-treated rats for a period of 18 h caused CMRGlc to rise above control values throughout the brain. However, there were no seizures or other evidence of brain dysfunction.

Alcohol Drinking↗
PubMed1991

Extramedullary hematopoiesis in cerebellar hemangioblastoma.

Extramedullary hematopoiesis and paraneoplastic erythrocytosis are uncommon in cerebellar hemangioblastoma, and their concomitant occurrence has not been reported. In a study of 26 cases of hemangioblastoma, we found extramedullary hematopoiesis in 4 tumors; one was associated with erythrocytosis. The significance of this association and the possible histogenetic origin of extramedullary hematopoiesis in cerebellar hemangioblastoma are discussed.

Adolescent↗
PubMed1991

Sternohyoid muscle biopsy. A diagnostic technique in respiratory failure of neuromuscular origin.

Patients with neuromuscular disease may develop respiratory failure requiring mechanical ventilation. We describe a sternohyoid muscle biopsy technique as a diagnostic aid in such patients undergoing tracheostomy for prolonged ventilatory support. The biopsy procedure is quick and without added discomfort or morbidity for the patient. Our preliminary observations in three patients suggest that the sternohyoid muscle biopsy may be a useful diagnostic tool in this selected group of patients.

Adolescent↗
PubMed1990

Five children with del (2)(q31q33) and one individual with dup (2)(q31q33) from a single family: review of brain, cardiac, and limb malformations.

Five matings to a dir ins (6;2)(q16;q31q33) carrier have produced a high frequency (42%) of offspring with unbalanced karyotypes. Five children have the derivative chromosome 2 resulting in del (2)(q31q33) and one individual received the derivative chromosome 6 leading to dup (2)(q31q33). The findings associated with the deletion include pre- and postnatal growth retardation, developmental delay, minor facial anomalies, seizures, complex structural heart defects, and limb deficiency. Autopsy of one individual showed complex brain malformations including hydrocephalus secondary to obstruction of the foramina of Monro, extensive heterotopias and polymicrogyria, and an unusual form of total anomalous pulmonary venous return. We compare the findings in these children to those of previously reported cases and construct an overview of the range of anomalies. Apparently, no other individual with dup (2)(q31q33) has been described. We compare the physical peculiarities of our patient with those of individuals with duplications of overlapping regions of 2q.

Abnormalities, Multiple↗
PubMed1990

Spinal cord ganglioglioma presenting as hydrocephalus.

We report a case of a 5 year old boy with a spinal cord ganglioglioma and hydrocephalus. The insidious onset with back stiffness and hamstring tightness, the diagnosis by magnetic resonance imaging, and the treatment by total excision is described. An adequate proven explanation for the hydrocephalus is lacking. Mechanisms which have been proposed include impaired cerebrospinal fluid absorption from increased cerebrospinal fluid protein, and arachnoiditis.

Child, Preschool↗
PubMed1990

Mannitol therapy in perinatal hypoxic-ischemic brain damage in rats.

To study the efficacy of mannitol in reducing cerebral edema and improving the ultimate neuropathologic outcome in perinatal cerebral hypoxia-ischemia, 67 7-day postnatal rats were subjected to unilateral common carotid artery ligation followed by exposure to 8% oxygen at 37 degrees C for 3 hours. Twenty-seven rat pups received a subcutaneous injection of 0.1 ml mannitol in a dosage of 4 mg/kg body wt immediately following cerebral hypoxia-ischemia and every 12 hours thereafter for a total of four doses. Control animals received either no therapy (n = 16) or an equivalent volume of normal saline (n = 24). Mannitol injections in six rat pups not subjected to hypoxia-ischemia produced no mortality but significantly increased serum osmolality from 287 to 361 mos/l (p less than 0.01). Preliminary studies indicated that substantial mortality occurred when greater doses of mannitol were administered to rats. After 48 hours of recovery from hypoxia-ischemia, the animals were killed and their brains were examined for either tissue water content (33 rat pups) or the presence of neuropathologic alterations (34 rat pups). Mannitol significantly reduced (p less than 0.001) brain water content, as a reflection of cerebral edema, in both the ipsilateral (88.5% compared with 90.6% in controls) and the contralateral (85.0% compared with 87.2% in controls) cerebral hemispheres. Mannitol therapy did not ameliorate the incidence, distribution, or severity of tissue injury in the cerebral cortex, subcortical white matter, hippocampus, striatum, or thalamus of the ipsilateral cerebral hemisphere compared with the controls. Thus, while mannitol substantially reduces the extent of cerebral edema following hypoxia-ischemia, no beneficial affect on ultimate brain damage occurs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Reduction of perinatal hypoxic-ischemic brain damage with allopurinol.

Cytotoxic free radicals are generated during cerebral hypoxia-ischemia and reperfusion. We studied the efficacy of allopurinol, a xanthine oxidase inhibitor and free radical scavenger, in reducing posthypoxic-ischemic damage in the developing brain of 7-d-old rat pups. Hypoxic-ischemic injury to the right cerebral hemisphere was produced by ligation of the right common carotid artery followed by 3 h of hypoxia with 8% oxygen. Thirty to 45 min before the hypoxia, the rats received either allopurinol (dose = 130-138 mg/kg) or an equal vol of saline (0.2 mL). Some pups were killed at 42 h of recovery for measurement of cerebral hemispheric water content, whereas others were killed at 30 or more d for neuropathologic examination. A total of 18 allopurinol treated rats had significantly less water content in the right hemisphere (89.07 +/- 0.32%) than 23 saline-treated animals (91.64 +/- 0.25%, mean +/- SEM, p less than 0.0001). Rank scoring of neuropathologic alterations revealed that the allopurinol treated rats were less damaged (p = 0.001). Only two of 13 brains from the allopurinol group suffered infarction compared to 10 of the 14 saline-treated animals. The results indicate that allopurinol reduces both cerebral edema and the extent of perinatal hypoxic-ischemic brain damage.

Allopurinol↗
PubMed1990

Physiologic and neuropathologic aspects of hypothermic circulatory arrest in newborn dogs.

A model of hypothermic circulatory arrest has been developed in the newborn dog. Ten puppies were anesthetized with halothane, paralyzed, and artificially ventilated with 70% nitrous oxide 30% oxygen to arterial oxygen pressure greater than 8.0 kPa (60 mm Hg), arterial carbon dioxide pressure of 4.4-5.6 kPa (33-42 mm Hg), and arterial pH of 7.35-7.42. Animals were surface cooled to 20 degrees C, after which cardiac arrest was produced with i.v. KCl. Dogs remained asystolic without ventilation for 1.0 (n = 4), 1.5 (n = 3), or 2.0 (n = 3) h. Resuscitation was accomplished with closed-chest compression, mechanical ventilation, i.v. epinephrine and NaHCO3, and rewarming to 37 degrees C. Postarrest recovery was maintained for 3-4 h; thereafter, the puppies underwent perfusion-fixation of their brains for pathologic analysis. Plasma glucose (control = 8.3 mmol/L) increased slightly during hypothermic cardiac arrest (+36%) but was markedly elevated at 15 min postarrest (20 mmol/L). Blood lactate (control = 1.1 mmol/L) increased almost 200% during hypothermic circulatory arrest, with a further rise to 9.0 mmol/L at 15 min postarrest. Thereafter, lactate decreased in the 1-h arrested dogs but increased progressively in the other groups. Mean arterial blood pressure returned to baseline (73 mm Hg) by 15 min postarrest, remained stable in the 1-h dogs, but fell at 3 h to 62 and 34 mm Hg in the 1.5- and 2.0-h groups, respectively. No neuropathologic alterations were seen in puppies arrested for 1 h, whereas all puppies arrested for 1.5 or 2 h had varying degrees of cerebral cortical and hippocampal damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Diffusely infiltrating brainstem gliomas: a report of the diagnostic difficulties in 2 cases.

Brainstem gliomas seem to present in 2 distinct ways. More commonly they are localized to 1 portion of the brainstem and present with signs that are both localizing and lateralizing. These are usually fairly easy to image neuroradiologically. The rarer diffusely infiltrating variety manifest a slowly building array of findings pointing to all levels and both sides of the brainstem. Our 2 cases exemplify the diffuse variety. They were clinically typical, and the CSF pressure and protein were elevated but the neuroimaging abnormalities were so subtle that they were originally overlooked. This subtlety of neuroradiologic abnormality resembles that found in gliomatosis cerebri.

Adult↗
PubMed1990

"Marden-Walker syndrome": neuropathologic findings in two siblings.

Neuropathologic examination of two siblings with phenotypic features consistent with Marden-Walker syndrome revealed central nervous system abnormalities which include reduction in the number of spinal anterior horn cells. The occurrence of these changes in a sibling pair provides strong evidence for a genetic etiology. The relationship between the neuropathologic changes and other phenotypic manifestations in this syndrome and in the closely related syndrome of Pena-Shokeir are discussed.

Abnormalities, Multiple↗
PubMed1989

Substantia nigra lesions in mercaptopropionic acid induced status epilepticus: a light and electron microscopic study.

Light microscopic and ultrastructural changes of substantia nigra were studied in paralyzed ventilated rats with status epilepticus induced by mercaptopropionic acid. Some rats were killed at the end of seizure activity and others were examined in varying intervals after the arrest of seizure. The earliest changes were reduction in the size of the neuronal nuclei and chromatin clumping followed by simultaneous distention of axons and dendrites. There was also enlargement of the neuronal perikarya associated with microvacuolation. This neuronal microvacuolation corresponded ultrastructurally to swollen mitochondria with disrupted cristae. These changes were followed by progressive neuronal shrinkage and astrocytic swelling. The swollen astrocytic processes together with swollen neurites gave a spongy appearance to the involved area. The lesion thereafter progressively enlarged and evolved into an area of frank necrosis containing abundant macrophages. This lesion is morphologically different from that produced in cortex and hippocampus by seizure activity or due to the direct effect of excitotoxins. The significance of substantia nigra pars reticularis changes and their pathogenesis are discussed.

3-Mercaptopropionic Acid↗