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Biomedical subjects

V T Miller

Publications and source records attributed to V T Miller.

35 records · Page 2Linked to original sources
PubMed1989

Heparin-induced thrombocytopenia.

There are two types of heparin-induced thrombocytopenia. Type I is more common, has an early onset, and is mild, transient, and benign. Type I is due to direct heparin-induced platelet aggregation and is rarely associated with thromboembolic sequela. Type II is infrequent, has a late onset, and is more severe. Type II is due to an immune-mediated platelet aggregation caused by IgG and IgM that becomes bound to platelets. In Type II, the antibody titers decline over several months; however, early reexposure can result in a catastrophic secondary immune response. Frequently, Type II is associated with life- or limb-threatening thromboembolic complications (white clots), including stroke.

Cerebrovascular Disorders↗
PubMed1988

Reproducibility of two in vivo tests of platelet function.

We correlated repeat determinations of platelet aggregate ratios (PAR) and plasma beta-thromboglobulin (BTG) in the right and left arms of thirty-four subjects in order to measure test reproducibility and to evaluate the effects of venipuncture. The reproducibility of PAR on the same blood samples was relatively low but similar to that obtained when the right arm and left arm values were compared, thus indicating little variation secondary to venipuncture. For BTG, the reproducibility on identical blood samples was quite high, but fell significantly when plasma samples from the two sides were correlated. This finding and increased BTG values when obvious blood collection problems occurred, indicated that plasma BTG levels are quite sensitive to venipuncture technique.

Humans↗
PubMed1987

Angiographic comparison of carotid arteries in unilateral cerebral ischemia.

We reviewed bilateral carotid angiograms of 74 patients with strictly unilateral carotid ischemic symptoms to evaluate asymptomatic atherosclerosis. Symptomatic arteries showed more stenosis than the asymptomatic counterparts, especially in patients with multiple TIAs, amaurosis fugax, or TIAs lasting less than 60 minutes. However, the frequency or degree of ulceration did not differ, and the proportion of stenotic lesions that appeared ulcerated was nearly equal on the symptomatic and asymptomatic sides.

Aged↗
PubMed1987

Acifran: a double-blind, randomized, placebo-controlled efficacy study in type IIa hyperlipoproteinemic patients.

The antihyperlipoproteinemic agent acifran (AY-25,712) was administered double-blind to 14 Type IIa hyperlipoproteinemic patients for 12 weeks in dosages of 100 mg t.i.d. or 300 mg t.i.d. An additional seven patients received placebo. Fasting plasma lipid and lipoprotein concentrations were determined at baseline (mean of 3 values), Week 8 (mean of 6- and 8-Week values), and Week 12 (mean of 10- and 12-Week values). At Week 8, patients receiving acifran 100 mg t.i.d. showed low-density lipoprotein (LDL) cholesterol levels which were 13% lower than pretreatment baseline (p less than 0.01) and 14% lower than patients given placebo (p less than 0.05); high-density lipoprotein (HDL) cholesterol levels were 11% higher compared with either baseline or the placebo group (p less than 0.05); the LDL/HDL ratio was 20% lower than baseline (p less than 0.001) and 21% lower than the placebo group (p less than 0.05); total cholesterol was 8% lower than that of the placebo group (p less than 0.05). There was no apparent relationship between changes in plasma lipid concentrations and acifran dose or treatment duration except for triglycerides, which at Week 12 were 25% lower than baseline (p less than 0.001) and 35% lower than the placebo group (p less than 0.05) only in the acifran 300 mg t.i.d. group, in which HDL-cholesterol was concurrently 18% higher compared with placebo (p less than 0.05). In this 12-week study acifran provided safe and effective treatment for Type IIa hyperlipoproteinemia.

Adult↗
PubMed1986

Progestins and oral contraceptive-induced lipoprotein changes: a prospective study.

In order to determine the effects on plasma lipoproteins of oral contraceptives containing progestins with varying androgenic potency, 136 healthy women were randomized into 3 groups and followed prospectively for one year while receiving either 50 mcg ethinyl estradiol and 1.0 mg ethynodiol diacetate (EED), 50 mcg ethinyl estradiol and 1.0 mg norethindrone acetate (ENA), or 50 mcg ethinyl estradiol and 0.5 mg d-1 norgestrel (ENG). Comparison was made to a self-selected group of 50 women using alternative means of contraception. Plasma cholesterol increased by 7-9% and triglycerides by 32-57% in all 3 groups (p less than 0.05). ENG use resulted in other significant lipoprotein changes including an 18% increase in low density lipoprotein cholesterol (LDL-C), a 13% fall in high density lipoprotein cholesterol (HDL-C) and a 27% decline in HDL2 cholesterol (HDL2-C) (p less than 0.05). Apoprotein A-I (Apo A-I) increased by 9% with ENA and by 11% with EED (p less than 0.05), but did not change significantly with ENG. This prospective study demonstrates that in oral contraceptive agents with identical estrogen, progestins with different androgenic potency produce major and different changes in plasma lipoproteins.

Adolescent↗
PubMed1986

Tobacco intolerance in multiple system atrophy.

In a patient with multiple system atrophy, the ataxia was temporarily exacerbated by cigarette smoking. The phenomenon is attributed to a direct effect of nicotine on the central nervous system, rather than being secondary to autonomic changes. Its prevalence and specificity are currently unknown.

Autonomic Nervous System Diseases↗
PubMed1984

Prostacyclin infusion in acute cerebral infarction.

We gave prostacyclin infusions to seven patients with acute cerebral infarction. Patients without CT evidence of infarction improved, but those who already had hypodensities on CT did not benefit. Increased platelet activity, measured by plasma beta-thromboglobulin, decreased significantly (p less than 0.01) during prostacyclin administration to normal levels, but rose again after the infusion. These results indicate that prostacyclin can be given safely in doses adequate to suppress platelet function. Our findings encouraged us to proceed with a controlled trial of its clinical efficacy.

Acute Disease↗
PubMed1983

Lacunar stroke. A reassessment.

Lacunae are small, deep cerebral infarcts known to occur in hypertensive patients. Although frequently asymptomatic, they sometimes produce characteristic clinical syndromes. Postmortem studies have implicated small-vessel disease in their pathogenesis, and, as a result, conservative management has been advocated. Computed tomography (CT) has provided new insights into the spectrum of lacunar disease. Review of recently acquired information suggests modifications of the approach to these patients. The clinical lacunar syndromes, though nonspecific, do suggest lacunar infarction. In hypertensive patients with these syndromes and CT confirmation of lacunar infarction, a conservative diagnostic posture coupled with medical management of risk factors continues to be indicated.

Cerebral Infarction↗
PubMedDate not supplied

Cardioembolic vs. noncardioembolic strokes in atrial fibrillation: frequency and effect of antithrombotic agents in the stroke prevention in atrial fibrillation studies.

BACKGROUND: While atrial fibrillation (AF) increases the risk of cardioembolic stroke, some ischemic strokes in AF patients are noncardioembolic. OBJECTIVES: To assess ischemic stroke mechanisms in AF and to compare their responses to antithrombotic therapies. METHODS: On-therapy analyses of ischemic strokes occurring in 3,950 participants in the Stroke Prevention in Atrial Fibrillation I-III clinical trials. Strokes were classified by presumed mechanism according to specified neurologic features by neurologists unaware of antithrombotic therapy. RESULTS: Of 217 ischemic strokes, 52% were classified as probably cardioembolic, 24% as noncardioembolic, and 24% as of uncertain cause (i.e., 68% of classifiable infarcts were deemed cardioembolic). Compared to those receiving placebo or no antithrombotic therapy, the proportion of cardioembolic stroke was lower in patients taking adjusted-dose warfarin (p = 0.02), while the proportion of noncardioembolic stroke was lower in those taking aspirin (p = 0.06). Most (56%) ischemic strokes occurring in AF patients taking adjusted-dose warfarin were noncardioembolic vs. 16% of strokes in those taking aspirin. Adjusted-dose warfarin reduced cardioembolic strokes by 83% (p < 0.001) relative to aspirin. Cardioembolic strokes were particularly disabling (p = 0.05). CONCLUSIONS: Most ischemic strokes in AF patients are probably cardioembolic, and these are sharply reduced by adjusted-dose warfarin. Aspirin in AF patients appears to primarily reduce noncardioembolic strokes. AF patients at highest risk for stroke have the highest rates of cardioembolic stroke and have the greatest reduction in stroke by warfarin.

Aged↗
PubMedDate not supplied

Cerebral infarction associated with lupus anticoagulants--preliminary report.

Hypercoagulability may contribute to stroke in young adults. Lupus anticoagulants (LA) were identified in six patients (4%) of 145 young adults with cerebral infarction. The clinical features of the 6 patients in this survey plus an additional patient from another institution with LA-associated stroke are presented. Four had systemic lupus erythematosus and 3 had idiopathic LA; all had mild thrombocytopenia. In 2 patients, no other conditions associated with stroke were discovered after thorough evaluation. Recurrent arterial thrombosis occurred in 4 of 7 patients during an average of two years of follow-up. Evidence suggests that inhibition of prostacyclin formation may occur with LA, promoting a prothrombotic state.

Adolescent↗