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Biomedical subjects

K Welch

Publications and source records attributed to K Welch.

At least 55 records · Page 3Linked to original sources
PubMed1991

Results of surgery for extratemporal partial epilepsy that began in childhood.

Thirty-five consecutive patients who underwent surgery for intractable extratemporal seizures originating in childhood are described. Candidates for surgery were selected on the basis of clinical criteria, neurodiagnostic imaging, and an electroencephalographic investigation that included the use of sphenoidal electrodes and long-term monitoring. Invasive preoperative monitoring was not used. Our results, with respect to the control of seizures and behavioral improvement, are comparable with series in which data from invasive recordings were used in the selection process. Sixty-three percent of the 35 patients (76.5% of those operated on after the introduction of long-term electroencephalographic monitoring) became either seizure free or experienced a reduction in their frequency of seizures by at least 75%. The favorable outcome in this group of patients strengthens the argument for early operation in children with intractable epilepsy, even when the seizure focus is outside the temporal lobe.

Adolescent↗
PubMed1990

Craniopharyngiomas in children. Long-term effects of conservative surgical procedures combined with radiation therapy.

Thirty-seven patients with craniopharyngioma were treated at Children's Hospital, Boston, between 1972 and 1981, the mean follow-up period now being 10.5 years. Twenty of these patients are old enough to have finished high school and have been queried about their college or job activity. None of the four patients who had undergone radical excision of their tumor and who had reached the age of finishing high school was able to work independently. Among the 16 patients who reached this age and who were treated by more conservative operations and irradiation or irradiation alone, job performance or college attendance varied considerably, indicating that psychosocial impairment occurred in this group, but suggesting that the risk was less. The rate of tumor recurrence or of failure to respond to treatment was 57% (four of a total of seven survivors) following radical surgery and 7% (two of 27 survivors) after conservative operations and irradiation. The overall mortality rate was 8%; the causes of the three deaths were: "hypothalamic crisis" 1 year after radical resection; progressive tumor growth despite two attempts at resection and irradiation; and a brain-stem glioma in the field of irradiation 8 years after treatment.

Child↗
PubMed1990

Cloned stromal cell lines derived from human Whitlock/Witte-type long-term bone marrow cultures.

We report a human bone marrow culture technique that initially parallels the murine Whitlock/Witte culture system. As in the murine system, B cells predominate over other cell types, and all differentiation stages from pre-B to plasma cell are observed. Although these human long-term cultures pass through stages resembling phases I to III of murine Whitlock/Witte cultures, no outgrowth of nonadherent cells was seen after cultures had reached the "crisis" phase unless Epstein-Barr virus (EBV)-transformants appeared. The stromal cells persisted well beyond crisis, but they could not be maintained and passaged as cell lines, limiting their use in molecular analysis. Transfection of these stromal cells with plasmid DNA containing the simian virus 40 (SV40) early region yielded 124 cloned cell lines. Analysis of these lines showed that all expressed SV40 large T antigen, but they retained most phenotypic markers found on non-transformed stromal cells. When adherent and T-cell-depleted bone marrow cells were cultured on either nontransformed stromal layers or transformed cell lines they proliferated actively and soon yielded predominantly lymphoid nonadherent populations. Moreover, prolonged survival of acute lymphoblastic leukemia cells of pre-B phenotype was regularly achieved on both normal and transformed adherent cell layers. Although the liquid culture system favored lymphocytes, transformed stroma supported colony formation by both human and murine hemopoietic progenitors when marrow was added in agar medium. This was not explained by colony-stimulating factor (CSF) production, because striking heterogeneity in the levels of granulocyte CSF (G-CSF) and granulocyte-macrophage CSF (GM-CSF) secretion by the lines was noted. Some lines that did not produce detectable CSF demonstrated good support of fresh bone marrow growth and acute lymphoblastic leukemia (ALL) cell survival. The heterogeneity of these cell lines and their capacity to support hemopoiesis suggest that they will be useful in studying the molecular basis of in vitro lymphohemopoiesis in man.

Age Factors↗
PubMed1989

Cognitive and social-emotional development of children in different preschool environments.

62 English-speaking preschool children were divided into three groups, a Montessori group (n = 21), a traditional preschool group (n = 21), and a homestaying group (n = 20) to compare their relative cognitive and social-emotional development. Significant differences in favour of the school groups were found for vocabulary, language comprehension, ability to judge the correctness of figural stimuli, visual memory, and perceptual organization. No differences were found for social-emotional development, and no relationship existed between type of preschool and level of development.

Child↗
PubMed1989

The effect of furosemide on intracranial pressure and hemorrhage in preterm rabbits.

The hypothesis that intracranial hypotension due to excessive postnatal fluid loss places the premature infant at risk for germinal matrix and intraventricular hemorrhage (GM-IVH) was tested in preterm rabbits delivered at 28 and 29 days of gestation (term 32 days). Furosemide administered to newborn pups induced a diuresis that resulted in a 11% to 22% loss in body weight and a concomitant decline in muscle water (13% to 16%) and sodium (18% to 21%). Paradoxically, no change occurred in the water or electrolyte content of the brain even though cerebrospinal fluid and brain tissue pressure, but not blood pressure, declined. These changes were absent in littermates treated with saline. Microscopic examination of brain sections revealed a greater incidence of intracranial hemorrhage, particularly in the germinal matrix and choroid plexus, in furosemide-treated than in saline-treated preterm rabbit pups. These results are consistent with the hypothesis that intracranial hypotension promotes the incidence of GH-IVH in preterm animals.

Animals↗
PubMed1988

Routine culture of stool specimens for Yersinia enterocolitica is not a cost-effective procedure.

Cefsulodin-Irgasin-novobiocin (CIN) agar was used to isolate Yersinia enterocolitica from 3,622 stool specimens received in our laboratory during a 1-year period. Seven specimens (0.2%) yielded Y. enterocolitica strains from a total of five patients. The low frequency of Y. enterocolitica isolation observed, coupled with the isolation of this pathogen from three of the five patients by our standard stool examination protocol, leads us to conclude that routine culture of stool specimens on CIN agar is not a cost-effective procedure.

Cost-Benefit Analysis↗
PubMed1988

Simple microbiologic detection of Campylobacter pylori.

A study of 84 gastric biopsies taken from 42 adult patients revealed simple techniques for Gram stain and culture for Campylobacter pylori. In an initial study of 18 biopsies, Gram stains prepared from ground, diluted tissue were all negative for curved, gram-negative rods, whereas 13 of these specimens were positive for C. pylori by culture. The Gram stains for the remaining 66 biopsies were prepared by a rinse-imprint technique. In this group, there were 30 Gram stains positive for organisms resembling C. pylori and 32 positive cultures. By Gram-staining two sites, fundus and antrum, the sensitivity of the Gram stain for identifying a positive specimen increased from 91 to 100%. Gram stain may be the preferred technique for rapid diagnosis. When cultured, C. pylori was recovered most often on modified Thayer-Martin medium incubated microaerophilically at 35 degrees C. The presence of antibiotics in modified Thayer-Martin medium limited upper respiratory flora overgrowth, which was often present on nonselective media.

Biopsy↗
PubMed1987

Brain tissue pressure measurements in perinatal and adult rabbits.

Brain tissue pressure (BTP) in pre- and post-natal anesthetized rabbits, held in a stereotactic head holder, was measured with a fluid filled 23 gauge open-ended cannula connected distally to a pressure transducer. By advancing the cannula step wise through a hole in the cranium it was possible to sequentially measure pressure from the cranial subarachnoid space, cortex, ventricle and basal ganglia. Separate cannulas and transducers were used to measure CSFP from the cisterna magna and arterial and/or venous pressure. Pressure recordings obtained when the tip of the BTP cannula was located in the cranial subarachnoid space or ventricle exhibited respiratory and blood pressure pulsations equivalent to and in phase with CSF pulsations recorded from the cisterna magna. When the tip was advanced into brain parenchymal sites such pulsations were suppressed or non-detectable unless communication with a CSF compartment had been established inadvertently. Although CSF pressures in the three spinal fluid compartments were equivalent, in most animals BTP was higher than CSFP. However, after momentary venting of the system BTP equilibrated at a pressure below that of CSFP. We speculate that venting of the low compliance system (1.20 x 10(-5) ml/mmHg) relieves the isometric pressure build-up due to insertion of the cannula into brain parenchyma. Under these conditions, and at all ages examined, BTP in the rabbit is consistently lower than CSFP and, as with CSFP, it increases as the animal matures.

Age Factors↗
PubMed1986

Furosemide lowers intracranial pressure by inhibiting CSF production.

Furosemide administration effectively lowers intracranial pressure in newborn preterm and term rabbit pups. This effect may be due to the diuretic action of the drug, its ability to inhibit cerebrospinal fluid production or to a combination of both. To test these possibilities newborn rabbits were either injected with furosemide and left unmolested for 6 hours, or anaesthetized and subjected to ventriculocisternal perfusions. During the 6 hour postnatal period the decrease in body weight was 8 times greater in furosemide than in saline treated pups. However, no difference was noted between the average brain weights of these two groups. Secondary effects of the diuretic were noted in blood (12.5% increase in the haematocrit over control value) and in muscle in which tissue water content and NA+ concentration were decreased while K+ concentration was increased. The fact that these parameters remained unchanged in brain suggests that the lowering of intracranial pressure was not attributable to the secondary effects of the diuretic agent. However, the marked reduction in cerebrospinal production noted following furosemide administration indicates that in newborn rabbits this may represent the primary mechanism by which furosemide lowers intracranial pressure.

Animals↗
PubMed1986

The thymus in AIDS.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Traumatic parturitional intracranial hemorrhage.

Twenty-five cases of intracranial hemorrhage due to injury at birth, encountered over a seven-year period, are presented. CT scans showed many different pathways of spread of tentorial hemorrhage; the likelihood of an arterial source is emphasized. Recurrent or delayed bleeding was documented twice. Surgical evacuation of hematomas was necessary in 10 cases, seven involving hemorrhage into the posterior fossa. There were three deaths, one due to pulmonary hemorrhage complicating subtentorial subdural hematoma, another due to severe central parenchymal hemorrhage and a third because of postoperative cerebellar hemorrhage due to disseminated intravascular coagulation. Three survivors are dependent on shunts, two because of the birth injury. The outcome for neurological and intellectual function depends more on associated asphyxia than on the trauma.

Arteries↗
PubMed1986

Vasculature to the germinal matrix in rabbit pups.

The authors report a study of the cerebral vasculature of premature rabbits pertaining to the germinal matrix (GM). A pigmented silicone material (Microfil) was injected into the carotid artery of anesthetized rabbits. Methyl methacrylate vascular casts of a similar group of premature rabbits were examined by scanning electron microscopy. The GM is supplied by arteries from both the basal and convexity surfaces of the brain. Vessels could be identified as arteries or veins by their typical patterns of branching and by the characteristic impressions made on the methyl methacrylate casts by endothelial nuclei. Specific evidence of structural weaknesses in the vasculature, which could be a site of predilection for GM bleeding, was not observed. The similarities in basal ganglia vasculature between premature rabbits and humans justifies using the rabbit model to study vascular aspects of the GM and intraventricular hemorrhage.

Animals↗
PubMed1985

The lowering of cerebral spinal fluid and brain interstitial pressure of preterm and term rabbits by furosemide.

CSF, brain interstitial, and arterial or venous pressures were measured in preterm and term rabbits. Ten to sixty minutes after the infusion of furosemide, in concentrations reported to inhibit CSF production, CSF and brain interstitial pressures fell an average of 1.4 and 1.8 cm H2O, respectively. No changes were observed in plasma osmolality, arterial or venous pressures. Histopathological examination of coronal brain sections showed the presence of germinal matrix and/or choroid plexus haemorrhages in four of eight brains examined. These results indicate that CSF and brain interstitial pressures of anaesthetised, restrained rabbits can be reduced to subatmospheric levels without altering serum osmolality. It remains to be established whether diminution of intracranial pressure by this method will increase the incidence of IVH in the awake, unrestrained preterm animal.

Animals↗