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Biomedical subjects

P Vo

Publications and source records attributed to P Vo.

10 recordsLinked to original sources
PubMed1999

The breast-feeding dilemma and its impact on HIV-infected women and their children.

The rate of HIV transmission via breast-feeding ranges from 14% to 26%, depending on the timing of maternal infection. In settings where infant mortality rates from infectious diseases and malnutrition are low and relatively safe alternatives to breast-feeding are available, HIV-infected mothers should be advised not to breast-feed. Where breast-feeding by HIV-infected mothers and bottle-feeding both present serious risks of mortality, changing the conditions in which families live so that safe feeding alternatives become available must be a top priority. At the same time, these mothers need information about the relative risks and benefits of breast-feeding, early weaning, wet-nursing, and formula feeding. This article reviews the available research data and discusses critical gaps in current knowledge.

Bottle Feeding↗
PubMed1996

Deficient nitric oxide responsible for reduced nerve blood flow in diabetic rats: effects of L-NAME, L-arginine, sodium nitroprusside and evening primrose oil.

1. This study examined the potential role of impaired nitric oxide production and response in the development of endoneurial ischaemia in experimental diabetes. Rats were anaesthetized (Na pentobarbitone 45 mg kg-1, diazepam 2 mg kg-1) for measurement of sciatic nerve laser Doppler flux and systemic arterial pressure. Drugs were administered into the sciatic endoneurium via a microinjector attached to a glass micropipette. 2. In two separate studies comparing diabetic rats (streptozotocin-induced; 8-10 wk duration) with controls, nerve Doppler flux in diabetic rats (Study 1, 116.6 +/- 40.4 and Study 2, 90.1 +/- 34.7 (s.d.) in arbitrary units) was about half that measured in controls (219.6 +/- 52.4 and 212.8 +/- 95.5 respectively; P < 0.005 for both). There were no significant differences between the two in systemic arterial pressure. 3. Inhibition of nitric oxide production by microinjection of 1 nmol L-NAME into the endoneurium halved flux in controls (to 126.3 +/- 41.3 in Study 1 and 102.1 +/- 38.9 in Study 2; both P < 0.001), with no significant effect in diabetic rats, indicating markedly diminished tonic nitric oxide production in the latter. D-NAME was without effect on nerve Doppler flux. 4. L-Arginine (100 nmol), injected after L-NAME, markedly increased flux in controls (by 65.8% (P < 0.03) and 97.8% (P < 0.01) in the two studies) and by proportionally similar amounts in diabetic rats [75.8% (P < 0.001) and 60.2% (P < 0.02)]. The nitro-donor, sodium nitroprusside (SNP; 10 nmol) had similar effects to L-arginine in both groups (increases of 66.0% in controls and 77.5% in diabetics; both P < 0.002). 5. A second diabetic group, treated with evening primrose oil performed exactly like control rats in respect of responses to L-NAME, L-arginine and SNP. 6. These findings implicate deficient nitric oxide in nerve ischaemia of diabetes and suggest correction thereof as a mechanism of action of evening primrose oil.

Animals↗
PubMed1995

Evaluating dorsal wrist pain: MRI diagnosis of occult dorsal wrist ganglion.

Fourteen patients with chronic dorsal wrist pain of unknown etiology underwent high-resolution magnetic resonance imaging (MRI) examination formatted to evaluate the scapholunate interval. Ten had MRI evidence that was diagnostic for an occult dorsal wrist ganglion. The average measured 4.7 mm at greatest diameter. Eight of 10 patients had the diagnosis confirmed, 7 at the time of surgery, and 1 at follow-up examination when the ganglion enlarged and was no longer occult. The other two opted for nonoperative management. The positive predictive value of a positive MRI finding for occult dorsal wrist ganglion was 100% in this small series. The use of a properly formatted high-resolution MRI in this patient population was diagnostic for occult dorsal wrist ganglion.

Diagnosis, Differential↗
PubMed1994

The aging spine: clinical instability.

Clinical instability of the spine is an intensely controversial subject, and its diagnosis, especially in the aging, is difficult. Yet success in its management rests on accurate diagnosis. Because both clinical presentation and radiographic manifestations are nonspecific, the diagnosis of clinical instability lies in understanding the biomechanics involved, in recognizing the relevant radiographic manifestations, and, most importantly, in correlating those observations with the patient's clinical history and physical examination. Stabilization is the treatment of choice for clinical instability. Strengthening of the dynamic stabilizers, especially early in the course of the disease, may prevent or alleviate the incapacitating symptoms of instability, and further research into this area should be undertaken. Static stabilization by bracing has not proved effective, and spinal fusion carries a high risk of complication. Fusion should be reserved for patients whose diagnosis is clear and whose symptoms are recalcitrant to conservative management. Further understanding of clinical spinal instability in the aging will require more precise definition of terms and better standardization of criteria for its diagnosis, management, and research.

Adolescent↗
PubMed1992

Food contains the bioactive peptide, cyclo(His-Pro).

Cyclo(His-Pro) (CHP) is a cyclic dipeptide with numerous biological activities. As small di- and tripeptides may be absorbed intact when ingested orally, we were interested in examining several common foods for the presence of cyclo(His-Pro)-like immunoreactivity (CHP-LI). In all foods tested, CHP-LI was found at levels 5-1500 times those previously found in human plasma. This CHP-LI was identical to authentic CHP by immunoidentity and chromatographic behavior. We conclude that 1) CHP-LI is readily detectable in several common food sources; 2) this CHP-LI is indistinguishable from authentic CHP; and 3) it is likely the CHP-LI in foods is absorbed in quantities sufficient to cause elevations of CHP-LI in plasma to biologically significant levels.

Chromatography↗
PubMed1991

Could dietary proteins serve as cyclo(His-Pro) precursors?

Cyclic dipeptides or diketopiperazines are readily generated during in vitro hydrolysis of proteins and polypeptides. This led us to examine whether cyclo(His-Pro) (CHP), a diketopiperazine containing histidine and proline, could be formed in vivo from dietary proteins. The data presented here show that at least in rat, neither urinary nor plasma concentration of CHP is elevated by consumption of a diet rich in proteins. Several dietary supplements derived from casein and/or soy protein hydrolysates, however, contain high levels of CHP-LI. Oral intake of one such supplement led to a sharp increase in the plasma level of CHP-LI.

Animals↗
PubMed1990

Preautopsy magnetic resonance imaging: initial experience.

To our knowledge, there are no prospective data in the literature investigating the role of magnetic resonance imaging (MRI) in detecting abnormalities in cadavers to determine the feasibility of this concept. We prospectively studied six cadavers (three stillborn infants, one infant, and two adults) with a 0.15 T resistive magnet. The images obtained allowed detection of abnormalities in multiple organs. Although autopsy was superior to MRI in detecting very small abnormalities, MRI was equal to autopsy in detecting gross cranial, pulmonary, abdominal, and vascular pathology in this small series. In addition, MRI was superior to autopsy in detecting air and fluid in potential body spaces. Preautopsy MRI may be an alternate method in restricted or denied autopsies and may provide an additional MRI research and educational tool.

Aged↗
PubMed1979

Lymphocyte toxicity in retinoblastoma.

Cytotoxicity can be used in the determination of patients with retinoblastoma. With further refinement, this type of test may become useful in aiding the physician in the detection of retinoblastoma.

Antibodies, Neoplasm↗
PubMedDate not supplied

Lymphocyte cytotoxicity testing in patients and families with retinoblastoma.

This study tested lymphocyte cytotoxicity from patients with retinoblastoma. Lymphocytes were tested against two permanent cell lines, WERI and Y-79. Normal volunteers served as controls. The lymphocyte reactivity of both patients with retinoblastoma and their mothers showed significant elevation compared with the controls. This strongly suggests that transplacental sensitization had occurred in utero and that the tumor was present prior to birth. Two children suspected of having retinoblastoma was tested and found to have elevated cytotoxicity titers but were later shown to have nematode inflammatory reaction. Both of their mothers' lymphocytes were not reactive to the tumor cell line. These results indicate that retinoblastoma can be present in utero with sensitization of the mother to the tumor. This test, with further refinement, may be applicable as a screening test in the differential diagnosis of retinoblastoma.

Child, Preschool↗