Biomedical subjects

K M Harris

Publications and source records attributed to K M Harris.

111 records · Page 7Linked to original sources

PubMedDate not supplied

Homocysteine and cardiovascular disease.

After a thorough review of the available literature, it appears that hyperhomocysteinemia is an independent risk factor for CHD. Furthermore, folic acid has been shown to reduce homocysteine concentration. Nevertheless, CHD is a multifactorial process, and many risk factors play a role in its pathogenesis. Several unanswered questions remain regarding the role of folic acid supplementation in hyperhomocysteinemia (Table 3). The absolute homocysteine concentration at which cardiovascular risk increases is not certain, and the magnitude of homocysteine-lowering needed to prevent events is unknown. Consequently, the number needed to treat cannot be calculated for folic acid supplements. Based on these data, the populations in whom to evaluate a homocysteine concentration have yet to be described. Because the POEMs are not yet available, it is unknown whether supplemental folic acid to lower homocysteine concentration will reduce CHD morbidity and mortality. It will take several years before any randomized, controlled trials are done, and primary prevention trials will need to be of very long duration to show any change in outcomes. Widespread use of folic acid supplementation has been recommended, however, and the need for clinical outcomes might be precluded. Even in the absence of outcome data, the potential benefits of using folic acid appear to outweigh any risks. A diet high in folic acid should be encouraged in everyone (Table 4). The FDA-mandated folic acid fortification of enriched grain products is most likely insufficient to lower homocysteine concentrations meaningfully, and a daily multivitamin that contains 400 microg of folic acid should be considered for patients who have documented CHD (especially when other risk factors are absent or in patients with premature atherosclerosis) and men and women who have cardiovascular risk factors, in addition to women of childbearing potential. Folic acid supplementation in the form of a multivitamin once daily is safe and inexpensive and might prevent the development and progression of CHD.

Cardiovascular Diseases↗

PubMedDate not supplied

Effects of prostaglandin E1 in twelve-hour lung preservation.

The effects of hypothermic lung preservation were evaluated in 12 mongrel dogs receiving double lung allografts. Animals underwent transplant procedures after 12 hours of static preservation at 4 degrees C following pulmonary artery flush with 60 to 80 ml/kg cold modified Collins solution. Donors were pretreated with allopurinol and recipients with methylprednisolone and perireperfusion deferoxamine. Six donor animals received a PGE1 infusion (20 to 500 ng/kg/min) for 20 minutes before harvest at doses causing a significant reduction in pulmonary vascular resistance. After implantation, recipients were maintained at ventilator settings identical to those used in donors. A fixed FIO2 (0.4) was maintained, except for 15-minute periods of FIO2 1.0 that were used to measure left-to-right intrapulmonary shunt fraction (Qs/Qt) and alveolar-arterial oxygen gradients (PAO2-PaO2). Cardiopulmonary function was studied for 20 hours. Pretreatment with PGE1 resulted in reduced survival (p less than 0.05) and increased PAO2-PaO2 (p less than 0.05) and Qs/Qt (p less than 0.05) 30 minutes after reperfusion. After 60 minutes of reperfusion, mean arterial pO2 (FIO2 0.4) was 148 mm Hg in controls and 80.5 mm Hg in the PGE1 group (p less than 0.02). There was no significant difference in pulmonary vascular resistance, cardiac output, mixed venous oxygen saturation, airway resistance, compliance and physiologic dead space between groups at any time after implantation. After 20 hours of reperfusion, pO2 (FIO2 0.4) in the control group was well maintained at 140 (+/- 52) mm Hg. The method of lung preservation in control animals resulted in good survival and adequate gas exchange after 12 hours of ischemia and 20 hours of reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Alprostadil↗

PubMedDate not supplied

Supporting teenagers' use of contraceptives: a comparison of clinic services.

A program to provide teenage family planning clinic patients with special services designed to improve their ability to practice contraception effectively and avoid conception produced neither of these expected effects. Two types of special services were tested in nine clinics: one, to promote greater involvement of the teenager's family through special counseling sessions (family support); and the other, to provide more frequent contact between the teenager and clinic staff through telephone calls (periodic support). The services were provided in the six weeks following the first clinic visit. Only 36 percent of the girls who agreed to be in the family support group attended any counseling sessions, and only five percent of them came with a parent. Participation was greater in the periodic support group--84 percent of teenagers in the group received the follow-up phone calls. During the 15 months following the initial clinic visit, there were no significant differences in regularity of contraceptive use and pregnancy rates between the teenagers who received the special support services and those who received only the regular clinic services. About 40 percent of the special-service groups reported always using a contraceptive method during the study period, compared with 48 percent of controls; and about 40 percent of the former said they had rarely or never used a method, compared with 27 percent of the latter. The cumulative 15-month pregnancy rate was about 13 percent in both the special-service and the control groups.

Adolescent↗