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Biomedical subjects

K Welch

Publications and source records attributed to K Welch.

At least 73 records · Page 4Linked to original sources
PubMed1985

Treatment of craniopharyngiomas in children: 1972-1981.

Between 1972 and 1981, 37 children with craniopharyngioma were cared for at Children's Hospital, Boston. In this paper, the results of treatment with radiation therapy after conservative operations are compared with those following an initial attempt to excise the tumor. Radiation therapy was equally, if not more, effective than attempted excision in controlling subsequent tumor growth. Although this was not a controlled study, the complications of each approach are indicated, and it is inferred that conservative operations combined with radiation therapy offer less risk for psychosocial impairment than does attempted tumor excision when patients are considered as a group. The ultimate effect that either approach might have on quality of life remains to be defined, and therapy must still be individualized to the particular clinical problem.

Child↗
PubMed1984

Autopsy findings in the acquired immune deficiency syndrome.

The medical records, premortem biopsy specimens, and autopsy materials from 36 patients with acquired immune deficiency syndrome (AIDS) were reviewed. The majority of the patients were homosexual men. Widely metastatic Kaposi's sarcoma was seen in eight patients, while tumor was confined to the skin in an additional ten. Four patients had high-grade lymphomas. Thirty-five of the 36 patients had at least one opportunistic infection at some point in the course of their illness. Many patients had multiple infectious agents. The most consistent and striking autopsy finding was a severe depletion of lymphoid tissues. Death in the majority (83%) of the patients was attributable to opportunistic infections affecting most commonly the respiratory tract (64%) and meninges (11%). Three patients (9%) died with widely metastatic Kaposi's sarcoma and secondary hemorrhage.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Radionuclide estimation of cerebrospinal fluid shunt flow. Evidence supporting an alternative theoretical model.

Flow of cerebrospinal fluid through a surgically implanted valve may be estimated by analyzing the disappearance curve resulting from the injection of a radiotracer into the valve. The standard method for estimating flow assumes an exponential disappearance of the tracer from the valve. This method models the valve as a single well-mixed compartment. Experimental evidence, showing that estimates of flow were dependent upon the site of injection, is at variance with this assumption. An alternative method of analyzing the disappearance curves, based on the area to height ratio (A/H) of the curves, was found to be more consistent with the experimental evidence and resulted in greater precision than the exponential method. It was concluded that optimal results are obtained using the A/H method with a fixed injection technique.

Cerebral Ventriculography↗
PubMed1983

Occupational risk for primary cytomegalovirus infection among pediatric health-care workers.

The risk of acquiring cytomegalovirus (CMV) from infected infants concerns pediatric health-care workers, particularly those who may be pregnant. We determined the prevalence of CMV antibody, and thus of past infection, in groups of medical students and house staff, nurses, and physicians, and in groups of pregnant and nonpregnant young women in the community. Although age, sex, and race influenced the results, occupation did not. We then estimated the exposure of the health-care workers by determining the prevalence of CMV infection in three groups of asymptomatic infants for whom they provided care; CMV was shed in urine or saliva of 1.6 per cent of newborns, 13 per cent of premature infants hospitalized for over a month, and 5 per cent of older infants seen in outpatient settings. When we determined the incidence of primary infection in the adult groups by retesting the seronegative members about two years later, we found that the annual attack rates in the medical students (0.6 per cent), house staff (2.7 per cent), and nurses (3.3 per cent) were not higher than in young women in the community (2.5 per cent during pregnancy and 5.5 per cent between pregnancies). We conclude that although pediatric health-care workers frequently and unknowingly care for infants shedding CMV, this occupational contact confers no greater risk than that faced by young women in the community at large.

Adult↗
PubMed1983

Evidence of prolactin receptors in the choroid plexus and a possible role in water balance in neonatal brain.

Tissue dehydration, including that of the brain, is a natural part of maturation. In the newborn it is accompanied by an acute salt water diuresis which is particularly pronounced in the premature infant. The decrease in cranial volume and fall in intracranial pressure to subatmospheric levels observed in premature infants after birth suggests that the brain shares in this process. Since fluid homeostasis is normally under hormonal control, the inordinate loss of fluid in the prematurely born may be attributable to a hormonal imbalance. The possibility that prolactin, a proven osmoregulatory hormone in submammalian species but not in mammals and primates, may have an important role in this process is suggested by recent evidence that prolactin regulates tissue water in fetal and newborn animals. If this hormone assists in the regulation of water and electrolyte content of the brain during the perinatal period then prolactin receptors might be expected at blood-brain and blood-CSF barriers. Our study with preterm, term and adult rabbits indicates that prolactin receptors are present and in much higher concentrations in the choroid plexus than in other tissues examined. Specific binding of prolactin to receptors on tissues normally is observed to increase with age. Since binding to the choroid plexus decreased with age it would suggest that the effect of prolactin on choroid plexus function may be more important during the perinatal than later stages of development.

Age Factors↗
PubMed1983

The role of intracranial hypotension in neonatal intraventricular hemorrhage.

Most preterm infants develop transient intracranial hypotension, which reaches its lowest level on the 2nd day of life. This corresponds to the time when most neonatal intraventricular hemorrhage (IVH) occurs. In order to test the hypothesis that intracranial hypotension may have an etiological role in the development of IVH in premature infants, the authors induced intracranial hypotension in the preterm rabbit by the intraperitoneal injection of glycerol. The rabbit model is well suited for this study because this animal is at risk of developing spontaneous germinal matrix and ventricular hemorrhage. Compared to control littermates, the glycerol-treated animals exhibited a greater than 3.5-fold incidence of germinal matrix and intraventricular hemorrhage.

Animals↗
PubMed1983

Congenital hydrocephalus due to villous hypertrophy of the telencephalic choroid plexuses. Case report.

A case of villous hypertrophy or bilateral papilloma of the choroid plexus of the lateral ventricles is reported. The child exhibited known features associated with overproduction of cerebrospinal fluid, hydrocephalus that was difficult to control, ascites after ventriculoperitoneal shunting, and relief after surgical removal of the papillomatous tissue. A unique feature is the complexity of the telencephalic choroid plexuses as shown by computerized tomography and ultrasound in the newborn period.

Cerebral Ventricle Neoplasms↗
PubMed1983

Neurological and psychophysiological sequelae following different treatments of craniopharyngioma in children.

The authors present neurological findings and data from psychophysiological tests administered during the follow-up period of 35 patients with craniopharyngioma. Group I patients who were treated by irradiation alone or by radiotherapy and conservative surgical procedures (including biopsy, cyst aspiration, and shunting), showed significantly less frontal lobe and visual perceptual dysfunction than Group II patients, in whom radical tumor resection was attempted by a subfrontal exposure. Frontal lobe dysfunction was demonstrated in sorting tests by perseverative responses, inflexibility of behavior, and lack of inhibitory control, while intelligence quotients remained relatively unaffected. Immediate memory defects and decreased manual dexterity were present, to different degrees, in both treatment groups. On the basis of these preliminary data and a maximum follow-up period of 10 years, the authors conclude that primary irradiation of a craniopharyngioma appears associated with a lower morbidity rate and may avoid the frontal lobe disorders seen in the patients with extensive tumor resection.

Adolescent↗
PubMed1982

Spontaneous germinal matrix and intraventricular hemorrhage in prematurely born rabbits.

Spontaneous hemorrhage into the ventricles in premature babies is a major problem, and neither its cause nor its pathogenesis is understood. A model is presented for the study of germinal matrix and intraventricular hemorrhage in the preterm rabbit. This animal is particularly suitable because, like the human, 1) the maximal growth of the brain occurs perinatally; 2) there is an abundant germinal matrix near term, and by birth this is substantially reduced; 3) there is no rete mirabile; 4) the blood flow to the brain is via the internal carotid and vertebral arteries; 5) the maturation of the lungs is completed just before term; and 6) the rabbit pup can maintain a separate existence from the dam when delivered prematurely. Eight of 64 such animals were found to have developed spontaneous germinal matrix hemorrhage with or without rupture into the ventricles. Several physiological and chemical features characteristic of the premature rabbit are presented. The hemorrhage in the lagomorph might be a paradigm of that in infants, and its study may aid in the understanding of the pathogenesis of the process.

Animals↗
PubMed1982

Cerebral hemangioma with glial neoplasia (angioglioma?). Report of two cases.

Two patients are reported who had intracerebral mass lesions composed of hemangioma and glial neoplasm. After excision, one recurred as an oligodendroglioma, and the remnant of the other remained static over a 5-year period. These lesions may represent a subgroup of cerebral hemangiomas that have the biological potential for future glial neoplastic growth. Reference is made to experimental work with polyoma virus which can induce cavernous hemangiomas in the central nervous system in mice, and which is a papovavirus. Other papovaviruses can induce ependymomas in hamsters.

Adult↗
PubMed1982

Surgical treatment of post-lumbar puncture dural CSF leak causing chronic headache. Case report.

A 58-year-old woman experienced incapacitating headache and occipital paresthesiae for 5 years after lumbar myelography. Conservative methods of treatment failed. Successive investigations for a suspected cerebrospinal fluid (CSF) leak were unrevealing. Leakage of CSF from the subarachnoid space into the epidural space in the lumbar region was finally confirmed when oil-soluble contrast material (Pantopaque), injected into the cervical subarachnoid space, was revealed by a specific technical modification to be escaping from the lumbar sac. Repair of the dural defect with dorsolumbar fascia resulted in almost complete alleviation of symptoms. This case is unusual because of the radiographic technique used, the duration of symptoms, and the rarity of reports of successful surgical treatment for this serious complication of lumbar puncture.

Cerebrospinal Fluid↗
PubMed1981

Influence of arsenic exposure and smoking on lung cancer among smelter workers: a pilot study.

A pilot study of 300 smelter workers from the cohort reported by Lee and Fraumeni [1969] has been studied: 150 men from their heavy exposure group and 150 men from the rest of the cohort randomly selected. Usable smoking habits were obtained from 86% of the sample. Estimates of the total lifetime work exposure were made from available measurements. A very high risk of lung cancer (SMR 1429) was observed among the most heavily exposed workers. Excess risks, though still present, were much less in those with lower exposures. There was a lower proportion of nonsmokers among the heavily exposed arsenic workers than among the other workers. This suggests that there may be some interaction between smoking and arsenic exposure. Moreover, comparison of smoking habits reported by smelter workers suggested that, as a group, they smoked more heavily than average for the United States population. A small study of proxy smoking histories suggested that these were valid and unbiased. The work continues on an enlarged sample.

Arsenic↗
PubMed1981

Changes in the water and electrolyte pattern of the brain and of the intracranial pressure during development in rabbits.

During its development the brain becomes dehydrated pari passu with growth and myelination and the electrolyte pattern changes from high sodium, low potassium to the opposite. The latter change is complete or virtually so in some species at term but in others the reversal is a postnatal occurrence. We have examined these features in rabbits of several ages and have measured the intracranial pressure at intervals during development as well. At or near both the water content of the brain is very high compared to that found later and the fetal electrolyte pattern is transitional in that the K/Na ratio is approximately one but not as high as in the mature brain. The intracranial pressure is lower in the newborn pups than it is later in development. Unlike that in mature animals the premature and young term rabbit brain is unable to affect ionic movements appropriate to the protection of the volume of the brain.

Animals↗
PubMed1981

The anterior tarsal tunnel syndrome. Report of two cases.

Two recently encountered patients with the anterior tarsal tunnel syndrome are presented. The various aspects of this probably under-recognized syndrome are discussed. Evidence is presented that this syndrome may be the result of abnormal stretch of the deep peroneal nerve.

Aged↗
PubMed1981

Chiari I "malformations"--an acquired disorder?

Caudal herniation of the hindbrain, indistinguishable from the Chiari I deformity, may occur after the establishment of spinal subarachnoid shunts and become symptomatic years after the procedure. Examples are presented and others are cited from the literature. It is proposed that the force responsible for the displacement is the difference in pressure between the cranial and spinal compartments. On the basis of these observations and other considerations as well, a similar process, disproportionate absorption of cerebrospinal fluid from the spinal region, might account for the spontaneous form of the Chiari I deformity.

Absorption↗
PubMed1981

Polychlorinated biphenyls and other organic chemical residues in fish from major United States watersheds near the Great Lakes, 1978.

Twenty-six composite samples of fish were collected during 1978 from United States watersheds near the Great Lakes and analyzed for polychlorinated biphenyls (PCBs) and related organic chemicals. PCB mixtures resembling Aroclor 1254 were found in all samples, and mixtures resembling Aroclor 1242 (or 1016) were found in 77 percent of the samples. Total PCB concentrations in the whole-fish composite samples ranged from 0.13 to 14.6 ppm; 65 percent of the samples contained more than 2 ppm PCBs. DDT and its metabolites were found in all samples. sigma DDT concentration was 1.66 ppm, and 81 percent of the samples contained less than 1.0 ppm sigma DDT. Chlordane ranged from less than 0.001 to 2.57 ppm in 38 percent of the samples. Hexachlorobenzene was found in 65 percent of the samples, ranging from less than 0.005 to 0.447 ppm. Other chemicals identified by gas chromatography/mass spectrometry included petroleum hydrocarbons and chlorobenzenes, chlorostyrenes, chlorophenols, and chlorinated aliphatic compounds. Fish from the Ashtabula River (Ohio), Rock River (Ohio), and Wabash River (Indiana) contained extremely complex residues of chlorinated and other organic chemicals.

Animals↗