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Biomedical subjects

W Siegel

Publications and source records attributed to W Siegel.

At least 19 recordsLinked to original sources
PubMed1995

Morning peak in ventricular tachyarrhythmias detected by time of implantable cardioverter/defibrillator therapy. The CPI Investigators.

BACKGROUND: A morning peak in occurrence of sudden cardiac death has been identified in epidemiological studies, but the studies are subject to selection bias, with the exclusion of unwitnessed deaths, which are more likely to occur at night. The recent availability of implantable cardioverter/defibrillators that record the time of ventricular tachyarrhythmias requiring either pacing or shock therapy provides an opportunity to clarify the timing of ventricular tachyarrhythmias predisposing to sudden cardiac death. Analysis of the timing of arrhythmias in different patient subgroups, such as patients with poor left ventricular function, may provide further insight into the mechanism of onset of sudden cardiac death. METHODS AND RESULTS: We studied patients in whom a cardioverter/defibrillator (Ventak PRx) was implanted between September 1990 and September 1993 in US centers. Events that could be timed occurred in 483 patients. With an RR cycle length of 240 ms as a cutoff, corresponding to a heart rate of 250 beats per minute, episodes were categorized as rapid (n = 1217) or less rapid (n = 9266) ventricular tachyarrhythmias. A higher proportion of both rapid and less rapid ventricular tachyarrhythmias began in the late morning compared with other times of the day. The subgroup of patients with ejection fraction < 20% at the time of implantation demonstrated a more uniform 24-hour distribution of tachycardias < or = 250 beats per minute than patients with higher left ventricular ejection fraction. CONCLUSIONS: Further investigation of the late morning peak and of precipitants of ventricular tachyarrhythmias by use of data from the implantable cardioverter/defibrillator may provide insight into the pathophysiological mechanisms causing sudden cardiac death.

Circadian Rhythm↗
PubMed1994

Serum lipids, neuroendocrine, and cardiovascular responses to stress in men and women with mild hypertension.

In this study, we examined the relation between serum lipid levels, gender, and cardiovascular and neuroendocrine stress reactivity in patients with mild hypertension. Ninety-nine individuals (62 men, 37 women) with mild hypertension performed four mental stress tasks: mental arithmetic, public speaking, cold stress, and a computer videogame. Cardiovascular reactivity scores were computed by subtracting the minimum resting blood pressure (BP) and heart rate (HR) values from the maximum values obtained during each task. Neuroendocrine reactivity was calculated as the change from epinephrine and norepinephrine values from mean rest to mean task. High and low reactors were identified on the basis of median splits of reactivity scores, averaged across all four stressors. High systolic blood pressure reactors had higher levels of total (TC), low-density lipoprotein cholesterol (LDL-C), and apo-B than did low reactors. High diastolic blood pressure reactors had lower levels of high-density lipoprotein cholesterol (HDL-C) and higher levels of LDL-C and apo-B than did low reactors. High HR reactors had higher apo-AI:apo-AII ratios than low reactors. Lipid levels were not different for high and low epinephrine and norepinephrine reactors. Although women were noted to have more favorable lipid profiles than men, both male and female hypertensive patients who were high reactors had less favorable lipid profiles than low reactors.

Adult↗
PubMed1990

[Experimental animal studies on the possibilities of bone reconstruction using preserved allogenic material].

Preserved allogeneic bone is possibly to repair the permanent shortness in autogeneic bone tissue in clinical practice. Complications as to the incorporation were observed after using lyophilised allogeneic implants. These were attributes to immunologic defense reaction. Demineralised bone caused a more intensive bone regeneration histologically than lyophilised bone. The clinical test of a superficial demineralised lyophilised preserved bone with osteoinductive potency and structural stability is recommended.

Animals↗
PubMed1985

Metastatic tumors of the mandibular condyle. Review of the literature and report of a case.

A metastatic tumor involving the mandibular condyle presented symptoms of temporomandibular joint (TMJ) dysfunction. Positive identification of the primary malignant lesion as prostatic adenocarcinoma was accomplished through the use of immunohistochemical stains for prostate-specific antigen and subsequent prostate biopsy. A review of the literature revealed fifteen additional cases of metastatic lesions of the mandibular condyle, seven of which also demonstrated TMJ-related symptoms as the initial manifestation of malignant disease. Such cases represent a diagnostic challenge, both clinically and microscopically. Symptoms of TMJ dysfunction coupled with radiographic evidence of a destructive lesion or pathologic fracture should suggest a possible malignant process indicating the need for biopsy. Subsequent examination of routine sections in combination with the use of selected stains, including immunohistochemistry may be helpful in identification of the primary tumor site.

Adenocarcinoma↗