The relationship of unsafe sexual behavior and the characteristics of sexual partners of HIV infected and HIV uninfected adolescent females.

PURPOSE: To compare characteristics of sexual relationships in HIV infected and HIV uninfected female adolescents and their association with condom use. METHODS: HIV infected and uninfected subjects, aged 13-19 years, were enrolled in a prospective HIV study from 15 sites in 13 U.S. cities. Baseline data on demographic information, substance use, sexual behavior, partner information, and condom use were collected through direct and computer-assisted interviews from currently sexually active females. Univariate, multiple logistic regression, and repeated measures analyses were employed. RESULTS: Data from 153 HIV infected and 90 HIV uninfected female subjects showed, on average, that current partners were 4-6 years older. In multivariate analysis, HIV infected subjects were older (OR = 1.37; 95% CI: 1.04-1.81), had more lifetime partners (OR = 2.23; 95% CI: 1.03-4.82), initiated consensual vaginal sex earlier (OR = .74; 95% CI:.58-.95), perceived partner to also be HIV infected (OR = 7.46; 95% CI: 3.2-17.4), and had less unprotected sex (OR = .27; 95% CI:.16-.45). Length of relationship was associated with more unprotected sex for both HIV infected and uninfected subjects (OR = 2.59, 95% CI: 1.27-5.27, OR = 4.13; 95% CI: 1.31-13.05, respectively). Mean partner age difference was greater among HIV infected than for HIV uninfected (OR = 1.06; 95%CI: 1.01-1.12); this greater age difference for HIV infected females was associated with less protection (OR = 1.09; 95% CI: 1.03-1.15). HIV disclosure influenced condom use: without disclosure, less condom use was reported (OR = 6.8; 95% CI: 2.29-20.24) controlling for perception that partner was also HIV infected (OR = 1.1; 95% CI: 1.02-1.21). CONCLUSIONS: Because age differential influenced reported condom use, more research, particularly qualitative, is needed into the dynamics of these relationships. Prevention efforts must address partners, particularly older ones.

Sites of plasmalemmal expansion in growth cones.

Studies on plasmalemmal expansion in isolated nerve growth cones identified large, clear vesicles characteristically found in growth cones as the plasmalemmal precursor. The present article examines these plasmalemmal precursor vesicles (PPVs) in greater detail in the intact cell. (a) Pulse-chase experiments with the phospholipid precursor, [3H]glycerol, followed by radioautographic analysis show that PPVs in distal neurites and growth cones are labeled prior to equilibration of the label with the plasmalemma. (b) Pulse-chase experiments with lectin-ferritin conjugates demonstrate that PPVs are not endocytotic, that they contain lectin receptors, and that, during growth, patches of lectin receptors appear on the plasmalemma covering PPV clusters. (c) Freeze-fracture studies show that this plasmalemma shares with PPVs a paucity of intramembrane particles. (d) Lectin labeling experiments and freeze-fracture analysis demonstrate, furthermore, that the plasmalemma forms a network of invaginations at the base of PPV clusters. (e) Correlative studies indicate that the refractive 'vacuoles' seen in growth cones by phase-contrast light microscopy correspond to the PPV clusters seen at the ultrastructural level. These results confirm the identity of the plasmalemmal precursor in the intact cell and demonstrate that PPV clusters form distinct, dynamic organelles specialized for plasmalemmal expansion in the growth cone.

Oral rehydration of infants in a large urban U.S. medical center.

A prospective randomized study of 100 well-nourished infants with acute gastroenteritis resulting in dehydration and acidosis was carried out at the Jackson Memorial Hospital, Miami from 1981 to 1983. Patients were randomly assigned to receive either standard intravenous therapy or oral rehydration. Infants in the latter group first received solution A containing 75 mEq/L sodium, 30 mEq/L potassium, 75 mEq/L chloride [corrected], 30 mEq/L bicarbonate, and 2 gm/dL glucose [corrected]. After ad libitum feeding for six hours, solution B containing 50 mEq/L sodium, 30 mEq/L potassium, 50 mEq/L chlorine, 30 mEq/L bicarbonate, and 3 gm/dL [corrected] glucose was given. With three exceptions (6%), oral rehydration was comparable to the intravenous regimen in clinical estimates of improvement, although the oral group had more stools in the first day. The oral group had faster correction of acidosis and a sustained rise in serum potassium concentration, whereas in the intravenous group the potassium concentration showed first a drop with a later increase, but levels were at all times below those in the oral group. Although potassium was given from the beginning of oral rehydration, and at a higher concentration than recommended by the World Health Organization, no hyperkalemia occurred. We concluded that oral therapy is safe, less expensive for patients, and more convenient for the medical and nursing staffs.

Lectin labeling of sprouting neurons. III. Type-specific glycoconjugates on growth cones of different origin.

Ferritin conjugates of various lectins were used to determine the densities of surface carbohydrates on nerve growth cones produced by different classes of neuron. These neurons, from superior cervical and dorsal root ganglia, spinal cord, olfactory bulb, and cerebellum of the fetal rat, were grown as explant cultures, labeled with the probes, and then processed for quantitative electron microscopic analysis. It has been observed that each type of growth cone carries a characteristic set of lectin receptors on its surface, a "surface carbohydrate signature." Neurons derived from the neural tube generally exhibit lower levels of lectin binding sites on their growth cones compared with those derived from the neural crest. However, after neuraminidase treatment, lectin labeling is consistently dense for all growth cone types. These findings suggest (i) that neurons are programmed, possibly at the time of neurulation, to generate high- or low-sialic-acid patterns of surface carbohydrates on their growth cones according to their origin, and (ii) that the specific glycoconjugate pattern found for each type of neuron may be involved in selective cell-cell interactions during nervous system development.

Nerve growth cones isolated from fetal rat brain: subcellular fractionation and characterization.

The biochemical and functional characterization of the nerve growth cone is of major interest for studies on mechanisms involved in nervous system development. We describe the isolation from fetal brain of membrane-bound fragments of nerve growth cones by density gradient fractionation. These so-called growth cone particles are highly uniform and identifiable on the basis of their organelle complement. Furthermore, they co-purify in mixing experiments with fragments of radiolabeled and light microscopically identified nerve growth cones from primary cultures. The possibility of isolating growth cone fragments in quantity renders feasible the analysis of molecular mechanisms involved in growth cone function.