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Biomedical subjects

W Stevenson

Publications and source records attributed to W Stevenson.

At least 19 recordsLinked to original sources
PubMed1998

School importance and dropout among pregnant adolescents.

PURPOSE: This study examined the relationship of psychological well-being, social support, and demographic variables to school importance and school dropout among pregnant teens. METHOD: Fifty-one Caucasians and 68 African-Americans (mean age = 16.7 years, mean weeks pregnant = 23) were recruited from two Baltimore area prenatal teen clinics. The adolescents completed questionnaires measuring depression, self-esteem, mastery, parental and friend support, demographic characteristics (i.e., age, marital status, ethnicity, socioeconomic status), school importance, and status. RESULTS: Most adolescents were enrolled in school or had graduated (69.7%), were receiving at least passing grades (78.7%), and perceived finishing high school as very important (76.7%). Blacks were more likely to say school was important (p < 0.001), were less likely to drop out (p < 0.01), and received higher grades (p < 0.01) than whites. Dropouts had lower family incomes than current school attenders and graduates (p < 0.05). One measure of psychological well-being (mastery, p < 0.01) was positively correlated with school importance. Social support did not correlate with school importance or dropout. CONCLUSIONS: These findings suggest that dropping out of school among pregnant teens may be more strongly related to sociocultural factors than to individual characteristics such as emotional support and psychological well-being. Overall, this study reveals a positive picture of educational continuation and performance during pregnancy, with most adolescents recognizing the importance of education and remaining in school.

Adolescent↗
PubMed1998

Sex ratio associated with timing of insemination and length of the follicular phase in planned and unplanned pregnancies during use of natural family planning.

This was a multicentred, prospective study of pregnancies among women using natural family planning. The women maintained natural family planning charts of the conception cycle, recording acts of intercourse and signs of ovulation (cervical mucus changes, including peak day and basal body temperature). Charts were used to assess the most probable day of insemination relative to the day of ovulation and length of the follicular phase of the cycle. The sex ratio (males per 100 females) for 947 singleton births was 101.5, not significantly different from the expected value of 105. The sex ratio did not vary consistently or significantly with the estimated timing of insemination relative to the day of ovulation, with the estimated length of the follicular phase or with the planned or unplanned status of the pregnancy. Although these findings may be affected by imprecision of the data, the study suggests that manipulation of the timing of insemination during the cycle cannot be used to affect the sex of offspring.

Family Planning Services↗
PubMed1996

Further evidence that infection is an infrequent cause of first trimester spontaneous abortion.

A previous cohort study found no clinical evidence that infection occurred more often in subjects experiencing pregnancy loss compared with those experiencing successful pregnancy [Simpson et al. (1996) Hum. Reprod., 11, 668-672]. Given these surprising findings, we conducted a similar analysis on another cohort also followed prospectively. Using couples practising natural family planning for conception or contraception, information on clinical evidence of infection was gathered beginning with week 5 of gestation. Information on fever and signs of overt infection was specifically sought by interview and physical examination. Frequencies of urinary, vaginal and other infections in subjects experiencing pregnancy loss were 11.1, 9.5 and 8.7% respectively, not significantly different from rates in subjects having liveborns (10.1, 10.2 and 10.3% respectively). Thus, no association between clinical infection and early pregnancy loss (< or = 16 weeks) was observed. Cohort studies utilizing biologically based assays are awaited because extant data do not provide evidence that clinically evident infections play major roles in first trimester pregnancy losses.

Abortion, Spontaneous↗
PubMed1995

Normocalcemic hyperparathyroidism associated with relatively low 1:25 vitamin D levels post-renal transplant can be successfully treated with oral calcitriol.

Since endogenous 1:25 vitamin D (1:25VD) is principally involved with involution of secondary hyperparathyroidism post-renal transplant we correlated 1:25VD levels with intact PTH in 82 random patients with a serum creatinine of < 2 mg/dl and with normal hepatic function. All patients studied were normocalcemic with normal phosphorus and received azathioprine, cyclosporin A and prednisone. Of considerable interest, of the 42 patients studied after 2 years post-transplant, there were 8 (19%) patients with intact PTH of more than twice the upper limit of normal (normal 10-65 pg/ml) and other 15 (36%) with PTH levels above normal. Secondly, in no patient did we see 1:25VD above normal (normal 15-60 pg/ml) despite levels of PTH of > 200 pg/ml. Of concern, 20% of 73 patients had 1:25VD deficiency (< 15 pg/ml). This may not have been previously appreciated because of the number of patients studied. Like previous investigators, we failed to understand why 1:25VD levels were relatively low. There was no correlation between 1:25VD and serum creatinine. Of 25 patients with a serum creatinine of 1.4 or less, there were 10 patients (40%) with 1:25VD of less than 20 pg/ml. Since persistently high PTH can contribute to bone demineralization, which is not uncommon post-transplant, we treated 8 patients with small doses of oral 1:25VD (rocaltrol). In less than 6 months PTH levels returned to normal in 7 of the 8 patients. The current studies clearly indicate that asymptomatic hyperparathyroidism is common even after 2 years post-renal transplant. Monitoring for PTH and 1:25VD will help prevent bone disease post-transplant now that rocaltrol is available.

Adolescent↗
PubMed1991

Efficacy of the symptothermal method of natural family planning in lactating women after the return of menses.

This study was designed to determine the efficacy of the symptothermal method of natural family planning during lactation. Although the method appears to give a reasonable reflection of fertility potential over time, it overlaps with the profound influence of lactation in both ovulation suppression and the delay of luteal phase adequacy. Further analysis is planned to attempt to identify those particular mucus signs and symptoms that are helpful during the transition from lactational amenorrhea to normal cycling.

Body Temperature↗
PubMed1989

Abdominal organ cluster transplantation for the treatment of upper abdominal malignancies.

Ten patients with primary malignant tumors of the biliary tract, duodenum, or stomach and with secondary involvement of the liver underwent removal of most or all of the stomach, liver, pancreas, spleen, duodenum, proximal jejunum, terminal ileum, and ascending and transverse colon. The void in the upper abdomen was filled with an organ cluster graft consisting of the liver, pancreas, duodenum, and variable segments of proximal jejunum. Eight of the ten patients are alive after 3 to 9 months, all with good liver and pancreas function, and most with satisfactory function of the gastrointestinal tract. One of the surviving patients was in the hospital for 4 months because of multiple enteric fistulas and infections; the other seven survivors were discharged after an average of 43 +/- 17.61 (SD) days. Recurrent tumor has not been proved in any of the surviving recipients and is suspected in only one. The study of such cases should provide insight and guidelines applicable to other visceral transplantation procedures that may be attempted in the future.

Abdominal Neoplasms↗
PubMed1988

Clinical and electrophysiologic effects of amiodarone in patients with atrial fibrillation complicating the Wolff-Parkinson-White syndrome.

The clinical and electrophysiologic effects of oral amiodarone were evaluated in 10 patients with a history of spontaneous atrial fibrillation and a rapid ventricular response, complicating the Wolff-Parkinson-White syndrome. Five patients developed ventricular fibrillation during an episode of atrial fibrillation. Seven patients underwent electrophysiology study and arrhythmia induction, both before and during chronic amiodarone treatment. During a mean 30 months of follow-up (range 8 to 59 months), no recurrences of atrial fibrillation or ventricular fibrillation were noted. One patient had recurrent supraventricular tachycardia and underwent surgery. One had serious and five had minor side effects. Arrhythmia suppression was associated with prolongation of the anterograde accessory pathway (+38%, p less than 0.01) and atrial (+34%, p less than 0.01) effective refractory periods. Amiodarone also slowed the ventricular response to induced atrial fibrillation, prolonging the mean (+90%, p less than 0.01) and minimum (+104%, p = 0.01) R-R intervals. Thus, amiodarone is a safe and effective alternative for arrhythmia prevention if surgery is inadvisable or is not desired by the patient.

Adult↗
PubMed1987

Programmed electrical stimulation in healed myocardial infarction using a standardized ventricular stimulation protocol.

The diagnostic accuracy of programmed electrical stimulation was prospectively assessed in 111 patients with myocardial infarction (MI) with or without a history of spontaneous ventricular arrhythmias. In 29 patients neither ventricular tachycardia (VT) nor episodes of 10 premature ventricular depolarizations per hour was documented. Fifty patients had documented nonsustained VT and 32 had sustained monomorphic VT. One and 2 extrastimuli (twice diastolic threshold, 2 ms in duration) were given during sinus rhythm and ventricular pacing at 100, 120 and 140 beats/min in the right ventricular apex (part I). When this protocol failed to induce a sustained monomorphic VT, a third extrastimulus was introduced (part II). Repetitive ventricular responses were induced in all patients, and in 15 (14%) polymorphic ventricular arrhythmias requiring DC shock were induced. Incidence of initiation of sustained monomorphic VT and polymorphic ventricular arrhythmias requiring DC shock was related to the clinical arrhythmia and the stimulation protocol. In patients with documented sustained monomorphic VT, a third extrastimulus only increased the incidence of sustained monomorphic VT (68% to 94%), whereas in patients with documented nonsustained VT and without VT the incidence of both polymorphic and monomorphic arrhythmias increased by 7 to 12%. Sustained monomorphic VTs induced in patients without such a history were faster (p less than 0.01), depended on site of MI (p less than 0.05) and were more often preceded by nonsustained polymorphic VT (p less than 0.01) than in patients with documented sustained monomorphic VT.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Dysrhythmias after direct-current cardioversion.

The success rate of direct-current (DC) countershocks and postshock arrhythmias are of concern for the design of automatic devices. Results of 112 DC shocks for induced ventricular tachycardia/fibrillation (VT/VF) (n = 99) or atrial fibrillation (AF) were analyzed. Clinical and arrhythmia characteristics were related to the success rate of DC shocks as well as postshock arrhythmias. Sixty-one patients were men and 14 were women; mean age was 52 +/- 15 years. Coronary artery disease was present in 56 patients and cardiomyopathy in 4. The other patients had no apparent structural heart disease. The success rate of transchest DC shocks for VT and VF were identical. The first DC shock interrupted 80% of VT and VF episodes. All episodes were terminated by 4 or fewer DC shocks. A single DC shock changed morphologic pattern or rate of 4 episodes of VT. Asystole after VT/VF (1,900 +/- 960 ms) was longer than after atrial fibrillation (1,150 +/- 470 ms, p less than 0.01). VT/VF recurred (within 3 minutes) after 26 of 99 initially successful DC shocks, requiring repeat shocks in 2 cases. Sinus bradycardia (n = 18) or high degree atrioventricular block (n = 11) necessitated rate support pacing in 10 patients. Antiarrhythmic drugs did not prevent postshock tachycardias, but facilitated the development of bradycardias. In conclusion, reliable and continuous analysis of cardiac rhythm after discharge is mandatory to enable automatic devices to correct unsuccessful discharges or recurring VT/VF. In addition, demand pacing capability is desirable to prevent severe bradycardia after DC shocks in patients receiving antiarrhythmic drugs.

Adult↗
PubMed1986

Importance of modes of electrical termination of ventricular tachycardia for the selection of implantable antitachycardia devices.

Different implantable systems for electrical treatment of ventricular arrhythmias are available. Information about mode of termination of ventricular tachycardia (VT) helps to select the most appropriate electrical treatment for drug-resistant VT. During 158 electrophysiologic studies, the mode of termination of 215 episodes of VT was analyzed in 2 groups of patients. Group 1 consisted of 54 patients with documented monomorphic VT and group 2 of 46 patients with other documented or suspected ventricular arrhythmias. Eighty-two patients had coronary heart disease, 8 had other structural heart disease and 10 had idiopathic VT. Termination of VT was attempted using extrastimuli and overdrive pacing; direct-current (DC) shocks were given in case of syncopal VT. During 33 of 96 studies (34%) in group 1, DC shock was required to interrupt VT, compared with 45 of 62 studies (73%) in group 2 (p less than 0.001). This difference was a result of less frequent induction of immediately syncopal VT in group 1 (14 of 129 VTs, vs 40 of 86 in group 2, p less than 0.001). Non-syncopal VT could reliably and safely be terminated by pacing in 61%, irrespective of the clinical arrhythmia. Pacing-induced acceleration of VT occurred in 6% (single extrastimuli) to 36% (over-drive pacing) (mean 26%) of attempts. Subsequent DC shock was required in half of these cases. Immediate collapse after induction of VT was not related to the presence of heart disease, but was related to a combination of VT cycle length (shorter than 260 ms) and left ventricular ejection fraction (less than 40%). Antiarrhythmic drugs reduced the need for DC shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Electrophysiologic basis for the suppression by amiodarone of orthodromic supraventricular tachycardias complicating pre-excitation syndromes.

Ten patients with refractory recurrent supraventricular tachycardia were found by electrophysiologic study to have bypass tracts and orthodromic atrioventricular reentrant tachycardia. All had failed to respond to conventional antiarrhythmic therapy and were therefore treated with oral amiodarone (1,600 to 2,000 mg/day for 2 weeks, then 800 to 1,200 mg/day for another 2 weeks with subsequent 200 to 600 mg/day maintenance doses). During or after the fourth week of therapy, electrophysiologic study was repeated. In 9 of 10 patients, supraventricular tachycardia could not be reinduced by programmed stimulation. In the remaining patient, nonsustained supraventricular tachycardia (greater than 10 beats, lasting less than 30 seconds) with a slower basic cycle length than that during the control period was provoked. Significant increases in the effective refractory period of the accessory pathway in both the anterograde (+26%, p less than 0.05) and retrograde (+40%, p less than 0.02) directions were noted, the magnitude of change being independent of the control effective refractory period. There were also significant increases in the effective refractory period of the right atrium (+24%, p less than 0.01) and the right ventricle (+15%, p less than 0.01) during long-term therapy with amiodarone. Over a mean follow-up period of 20 months, symptomatic control of the arrhythmia occurred in all patients; in only one patient treatment with amiodarone could not be continued because of side effects. These data establish the electrophysiologic basis for the effectiveness of amiodarone in the prophylactic control of refractory paroxysmal supraventricular tachycardia complicating the bypass tract syndromes.

Adult↗
PubMed1979

Immunity to equine herpesvirus 1 infection in foals during the first year of life.

A band of 23 pregnant mares on a Thoroughbred breeding farm all had serum virus-neutralizing antibody titres to equine herpesvirus 1 (EHV-1). Antibody was not transferred to their foals in utero. All foals received antibody from colostrum and developed antibody titres similar to their dams. The serum virus-neutralizing antibody titres were observed in 10 of these foals for 1 year. Decay of passive immunity occurred at the rate of 3.25 two-fold dilutions in 100 days and reached zero at the mean time of 180 days. The foals were exposed to EHV-1 twice. Foals with a geometric mean titre of 1 : 25 experienced infection and a rise of titre, while those with a geometric mean titre of 1 : 76 resisted infection.

Age Factors↗