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Biomedical subjects

W H Baker

Publications and source records attributed to W H Baker.

140 records · Page 8Linked to original sources
PubMedDate not supplied

Experimental Hematology Department, Armed Forces Radiobiology Research Institute, Bethesda, Maryland.

Granulocytes from dogs obtained by continuous-flow centrifugation leukapheresis were purified by counterflow centrifugation-elutriation using a modified rotor and enlarged separation chamber. The separation chamber has a threefold increase in volume capacity, as compared to the commercial Beckman Instruments' separation chamber, and the quantity and purity of the granulocytes recovered are suitable for purified granulocyte transfusion studies in a 10-kg canine animal model. Transfusion of these cells into cyclophosphamide-induced neutropenic animals permits an analysis of granulocyte chemotactic ability in terms of migration into skin chambers filled with endotoxin-activated serum. The purified granulocyte function in vivo was compared to the activity of granulocytes present in leukapheresis concentrates. The data show that transfused granulocytes isolated by counterflow centrifugation-elutriation from leukapheresis concentrates retain identical in vivo chemotactic activity, as compared to granulocytes present in transfused leukapheresis concentrates.

Blood Transfusion↗
PubMedDate not supplied

Trichloroethylene, trichloroacetic acid, and dichloroacetic acid: do they affect eye development in the Sprague-Dawley rat?

Maternal exposure to high doses of trichloroethylene (TCE) and its oxidative metabolites, trichloroacetic acid (TCA) and dichloroacetic acid (DCA), has been implicated in eye malformations in fetal rats, primarily micro-/anophthalmia. Subsequent to a cardiac teratology study of these compounds (Fisher et al. 2001, Int. J. Toxicol. 20:257-267), their potential to induce ocular malformations was examined in a subset of the same experimental animals. Pregnant, Sprague-Dawley Crl:CDR BR rats were orally treated on gestation days (GDs) 6 to 15 with bolus doses of either TCE (500 mg/kg/day), TCA (300 mg/kg/day), DCA (300 mg/kg/day), or all-trans retinoic acid (RA; 15 mg/kg/day). The heads of GD 21 fetuses were not only examined grossly for external malformations, but were sectioned using a modified Wilson's technique and subjected to computerized morphometry that allowed for the quantification of lens area, globe area, medial canthus distance, and interocular distance. Gross ocular malformations were essentially absent in all treatment groups except for the RA group in which 26% of fetuses exhibited micro-/anophthalmia. Using the litter as the experimental unit of analysis, lens area, globe area, and interocular distance were statistically significantly reduced in the DCA treatment group. Statistically significant reductions in lens and globe areas also occurred in the RA treatment group, all four ocular measures were reduced in the TCA treatment group but none significantly so, and TCE was without effect. Because DCA, TCA, and RA treatments were associated with significant reductions in fetal body weight (bw), data were also statistically analyzed after bw adjustment. Doing so dramatically altered the results of treatment group comparisons, but the severity of bw reduction and the degree of change in ocular measures did not always correlate. This suggests that bw reduction may not be an adequate explanation for all the changes observed in ocular measures. Thus, it is unclear whether DCA specifically disrupted ocular development even under these provocative exposure conditions. Clearly, however, if TCE is capable of disrupting ocular development in the Sprague-Dawley rat, a higher dose than that employed in the present study is required.

Administration, Oral↗
PubMedDate not supplied

Non-invasive evaluation of patients with extracranial to intracranial bypass.

In selected patients with cerebrovascular insufficiency, an extracranial-intracranial bypass is indicated to increase cerebral blood flow. To assess the effect of this operation upon routine non-invasive testing, 15 patients had oculoplethysmography, carotid phonoangiography and Doppler testing. None of those with a preoperative abnormality were changed after surgery, despite angiographically proven anastomotic patency. Whereas non-invasive tests may correctly identify severe internal carotid stenosis, use of these modalities in their routine form does not predict extracranial-intracranial bypass patency.

Carotid Artery Diseases↗
PubMedDate not supplied

An evaluation of hypocarbia and hypercarbia during carotid endarterectomy.

One hundred consecutive patients were randomly given hypocarbic (PaCO2 less than 25 torr) or hypercarbic (PaCO2 greater than 60 torr) general anesthesia during carotid endarterectomy to test the effect of the two regimens upon the incidence of postoperative neurological deficit. An indwelling shunt was not used. One patient died, two have permanent neurological deficits and two have temporary neurological deficits. Although hypocarbic patients had fewer neurological complications than hypercarbic patients, the difference was not statistically significant (p less than 0.13). Hypercarbia significantly increased the incidence of intraoperative arrhythmia. Also, no relationship was found between the incidence of postoperative stroke and the internal carotid back pressure or the time of carotid occlusion.

Anesthesia, General↗
PubMedDate not supplied

Amaurosis fugax.

We reviewed 112 patients with amaurosis fugax to refine our indications for carotid angiography. Eighty patients had a carotid endarterectomy. Thiry-four patients with ipsilateral hemispheric transient ischemic attacks plus amaurosis fugax all had an operable carotid lesion. The presence or absence of a carotid bruit, a normal or abnormal ophthalmologic examination, or a normal or abnormal cerebrovascular Doppler examination did not predict which patients would or would not have an operable carotid lesion. All patients with amaurosis fugax being evaluated for an operable carotid stenosis require angiography.

Angiography↗