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Biomedical subjects

D G Sherman

Publications and source records attributed to D G Sherman.

At least 19 recordsLinked to original sources
PubMed1992

Solid-phase time-resolved fluorescence detection of human immunodeficiency virus polymerase chain reaction amplification products.

A new assay system for the detection of polymerase chain reaction (PCR) amplification products is presented. This single-pot sandwich assay system employs solid-support oligonucleotide-coated capture beads, a rare earth metal chelate-labeled probe, and a time-resolved fluorescence detection. The new assay system was evaluated for various reaction conditions including, DNA denaturation time, hybridization salt concentration, probe concentration, and hybridization time, all of which are important in designing an assay with a high level of sensitivity for the detection of duplex DNA. This nonisotopic assay system was applied to the detection of purified human immunodeficiency virus (HIV) DNA and sensitivity was compared with agarose gel electrophoresis and slot blot hybridization using a 32P-labeled probe. We were able to detect the amplified product from one copy of HIV DNA after 35 cycles of PCR amplification in less than 30 min using this assay, which compared with one copy by gel electrophoresis after 40 cycles of PCR amplification and one copy by slot blot hybridization after 35 cycles of PCR amplification and an overnight exposure of the autoradiogram. Thus, this assay is rapid, sensitive, and easy to use.

Base Sequence↗
PubMed1992

Detection of human immunodeficiency virus type 1 RNA in plasma samples from high-risk pediatric patients by using the self-sustained sequence replication reaction.

There is an urgent need for rapid and sensitive methods to assess human immunodeficiency virus (HIV) infection in infants and children. We evaluated an approach by using the self-sustained sequence replication reaction (3SR) to amplify HIV type 1 (HIV-1) RNA directly. The amplified RNA product was then detected by bead-based sandwich oligonucleotide capture hybridization and rare earth metal chelate time-resolved fluorescence. The sensitivity of this technology was determined to be less than 12 HIV-1 RNA copies with an amplification level of 10(10)-fold with purified HIV-1 RNA. Plasma samples from 19 high-risk pediatric patients younger than 5 years of age were examined, and results were compared with viral culture of patient plasma. Results from plasma culture and 3SR amplification agreed for 14 of these patients and disagreed for 5. Of the five samples which did not agree, four were positive by 3SR and negative by culture and one was positive by culture and negative by 3SR but became positive by 3SR at a subsequent testing. We conclude that 3SR amplification coupled with time-resolved fluorescence is a promising technology for investigating the relationship between the presence of HIV-1 RNA in plasma and progression of disease in HIV-infected pediatric patients. This technology should be important in the assessment of HIV-1 infection, in evaluating drug therapies, and in understanding the pathogenesis and transmission of the virus.

Base Sequence↗
PubMed1991

Stroke prevention in nonvalvular atrial fibrillation.

There has been considerable uncertainty about the best way to prevent stroke in patients with nonvalvular atrial fibrillation. Recent studies have suggested that low-dose warfarin therapy, in addition to producing fewer bleeding complications, may be as effective as higher-dose therapy in preventing thromboembolic events. Four large, prospective, randomized trials have examined the risks and benefits of warfarin therapy for stroke prophylaxis in patients with nonvalvular atrial fibrillation. All four studies showed a substantially reduced incidence of stroke and a low incidence of significant bleeding in patients treated with warfarin. One of these studies also showed that aspirin reduced the incidence of stroke. The benefits associated with long-term low-dose warfarin therapy appear to exceed the risks for serious bleeding in most patients with atrial fibrillation. Aspirin may be a viable therapeutic option for patients who are unable to take warfarin or for those in subgroups at a low risk for stroke.

Aspirin↗
PubMed1991

Stroke prevention in nonvalvular atrial fibrillation: a review of prospective randomized trials.

Patients with atrial fibrillation are at risk for cerebral embolism; however, the roles of chronic anticoagulation or antiplatelet therapy for stroke prevention in patients with nonvalvular atrial fibrillation have been controversial. Recently, the results of three large prospective randomized trials that examined the risks and benefits of warfarin or aspirin for stroke prophylaxis in patients with nonvalvular atrial fibrillation were reported. All three studies revealed a reduction in the stroke rate for patients treated with warfarin and a small incidence of major bleeding. One of the studies also reported a reduced stroke rate in aspirin-treated patients. The reduction of thromboembolic events associated with chronic warfarin therapy appears to outweigh the risks of significant bleeding for most patients with nonvalvular atrial fibrillation. Aspirin may offer an alternative for subgroups of patients who are at low risk for stroke or those who are not good candidates for anticoagulation.

Anticoagulants↗
PubMed1991

Detection of Escherichia coli rRNA using target amplification and time-resolved fluorescence detection.

The development of technology to increase the sensitivity and speed of detection of bacterial pathogens in samples is important for diagnosis and monitoring of illness. We have developed a sensitive and rapid method for the detection of bacteria, using Escherichia coli as a model, which combines transcription-based target amplification with a bead-based sandwich hybridization assay using rare earth metal chelate labelled probes and time-resolved fluorescence detection. Using these methods as little as 100 copies (0.00016 attomoles) of purified native Escherichia coli rRNA or just one bacterial cell in a spiked sample could be detected. These results demonstrate that amplification of rRNA by transcription-based amplification and detection by time-resolved fluorescence provide a sensitive technology for the direct detection of micro-organisms without the requirement for prior cultivation.

Base Sequence↗
PubMed1990

Cardiac embolism: the neurologist's perspective.

Cardioembolic stroke represents a major healthcare challenge in the United States, accounting for significant morbidity and mortality, as well as economic and social costs. Determining the cause of ischemic stroke is often difficult because multiple potential etiologies are often present and available diagnostic tools are relatively insensitive. The diagnosis of cardioembolic stroke is based on a variety of clinical and laboratory clues that are significant, although not invariable, predictors of stroke etiology. Computed tomography scans help suggest etiology, and scans performed at 48 hours after stroke onset are essential to identify hemorrhagic infarctions. Cerebral angiograms may be helpful if performed early. Echocardiography is indicated only for selected patients who are more likely to demonstrate cardiac abnormalities on an echocardiogram. The management of acute cardioembolic stroke involves weighing the benefits of reducing stroke recurrence by anticoagulation against the risk of symptomatic brain hemorrhage. A management algorithm is provided that can help reduce both the risk of symptomatic brain hemorrhage and the incidence of potentially disabling stroke recurrence.

Coronary Disease↗
PubMed1990

Antiphospholipid antibodies and cerebral ischemia in young people.

The importance of a prothrombotic state as a cause of ischemic stroke in young adults is ill defined. We examined 46 unselected patients under age 50 years with cerebral ischemia for anticardiolipin antibody (aCL) and lupus anticoagulants (LA), over a 3-year-period. Age- and sex-matched patients with other neurologic diseases served as a noncerebral ischemia comparison group to test whether (1) stroke/transient ischemic attacks (TIA) in young people is associated with aCL and/or LA, and (2) their presence is specific to cerebral ischemia. In the stroke/TIA group, 21 patients had aCL or LA and 25 had neither, whereas in the control group, 2 patients had aCL and 24 had neither. Equal numbers of stroke/TIA patients with and without antiphospholipid antibodies (aPL) had other stroke risk factors. Patients with aPL and cerebral ischemia, however, had a more frequent history of multiple events than those without them. These antibodies occur with undue frequency in young patients with stroke/TIA and are not associated with a concurrent diagnosis of systemic lupus in most cases. A coexistent aPL-associated prothrombotic state may be a key determinant of whether patients with atherosclerosis, mitral valve prolapse, or other structural lesions experience recurrent ischemia.

Adult↗
PubMed1989

Stroke in the People's Republic of China.

Recent epidemiologic studies confirm that stroke is the most frequent cause of death in the People's Republic of China, with an incidence (219/100,000 people) more than fivefold that of myocardial infarction. Intracerebral hemorrhage causes about one third of all strokes, nearly three times the frequency in North American stroke registries. A marked regional variation in stroke incidence exists, with a threefold higher stroke incidence in northern than in southern Chinese cities, suggesting important environmental or dietary influences. Stroke treatment often involves a combination of modern and traditional herbal medicine; the latter may modify platelet aggregation and blood viscosity. Stroke, particularly intracerebral hemorrhage, is the most frequent and important vascular disorder in the People's Republic of China.

Cerebral Hemorrhage↗
PubMed1989

Neurologic manifestations of cardiac disease.

Although much has been written on the response of the heart to various intracerebral events including seizures, ischemia, intracerebral, and subarachnoid hemorrhage, less is known of the cerebral response to altered cardiac rhythm, cardiac failure, and cardiac arrest. The latter may alter central neuronal activity, cerebral blood flow, or cause ischemic damage. Such changes in cerebral function may lead to loss of consciousness, seizures, and focal neurologic deficits at the clinical level.

Brain Diseases↗
PubMed1989

The carotid artery and stroke.

Carotid artery atherosclerosis is the single most important cause of stroke. However, when transient ischemic attacks or strokes occur, it is important for the physician to consider other potential stroke mechanisms as well, including cardiac sources of embolus and intracranial arterial disease. Possible candidates for carotid endarterectomy include symptomatic patients with 75 percent or greater stenosis of the carotid artery and patients with ulcerated or less stenotic lesions in whom medical therapy has failed. Almost all patients with asymptomatic carotid stenosis should be managed with antithrombotic therapy and careful attention to risk factors.

Carotid Artery Diseases↗
PubMed1987

Atrial fibrillation and stroke: the view from neurology.

In summary NVAF is an important risk factor for stroke identifying a population at a six fold increased stroke risk. When stroke occurs it tends to be large and without a preceding TIA. These patients commonly have other cardiovascular disorders that must be considered as a potential cause of brain ischemia. The appropriate management of these patients to prevent cardioembolic stroke is unknown and must be individualized pending appropriate clinical trials. Following a cardioembolic stroke anticoagulation should be considered only in patients with small or moderate sized infarcts who have no evidence of hemorrhagic infarction on a CT scan and delayed until 36-48 hours post stroke onset.

Anticoagulants↗
PubMed1986

Thromboembolism and antithrombotic therapy in cerebrovascular disease.

The use of antithrombotic therapy of any type assumes a thrombotic mechanism for the patient's brain ischemia. Typical, but by no means specific, clinical and radiologic features of atherothrombotic, lacunar and embolic brain ischemia are outlined. The indications for anticoagulant therapy include progressing stroke and cardiogenic brain embolus. According to previous randomized trials, transient ischemic attacks should be managed with aspirin, 1.0 to 1.5 g daily, pending the results of studies of smaller aspirin doses and other platelet-active drugs. In patients with a suspected cardiogenic brain embolus, anticoagulation should be withheld pending the results of a computed tomographic scan done 24 to 48 hours from onset. If there is no evidence of hemorrhagic transformation or a large area of infarction and the patient does not have sustained hypertension, heparin therapy should be initiated in an effort to prevent a recurrent embolus.

Anticoagulants↗
PubMed1986

Cerebral embolism.

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Anticoagulants↗