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J D Malone

Publications and source records attributed to J D Malone.

44 records · Page 3Linked to original sources
PubMed1982

The relationship of monocytic cells to the differentiation and resorption of bone.

Osteogenesis in the developing limb is, as elsewhere, the result of two functionally integrated processes, bone matrix synthesis and matrix degradation. The latter process is a manifestation of the resorptive activity of osteoclasts (OCs), multinucleated giant cells which arise by fusion of mononuclear, blood-borne precursors. For the past several years, we have focused our efforts on several different aspects of OC development and differentiation. These efforts have included observations on patients with osteopetrosis, an analysis of monocyte (OC precursor) chemotaxis in response to bone matrix proteins, and the use of histochemical and bone grafting techniques to establish the lineage and expression of the osteoclast phenotype in the avian embryonic limb. Here, we (1) briefly review the evidence establishing the hematopoietic and probable monocytic origin of OCs, (2) present new data on the role of L-gamma-carboxyglutamic acid in osteocalcin-evoked chemotaxis and (3) describe the time course and likely developmental relationships between the appearance of circulating OC precursor cells, osteoclast differentiation, and the formation of mineralized bone matrix in the chick embryo. The results of the latter study indicate that OC differentiation is initiated by contact between precursor cells and mineralized bone, and suggest that the expression of the OC phenotype is dependent upon proteins or glycoproteins closely associated with bone mineral. We note that osteocalcin is one such protein.

Acid Phosphatase↗
PubMed1981

Glucocorticoid enhancement of bone resorption by rat peritoneal macrophages in vitro.

The issue of the direct action of glucocorticoids on bone resorption was addressed in a model system consisting of a pure (99%) population of putative osteoclast precursors, namely thioglycollate-elicited rat macrophages cocultured in vitro in devitalized rat bone particles which had been prelabeled in vivo with 45Ca. After 4 days in culture, these macrophages mobilized a net 20-30% 45Ca from bone. The addition of cortisol in physiological concentrations (10(-8) M) elicited significant (P less than 0.001) increases in isotope mobilization; optimal enhancement occurred at 10(-6) M and approximated the circulating level achieved with high dose glucocorticoid therapy. Other steroids, specifically aldosterone, 17 alpha- and beta-estradiol, 11-deoxycortisol, and progesterone, did not enhance the resorptive process. The augmentation of bone 45Ca mobilization by cortisol-treated macrophages was not due to protracted cell viability in culture or the increased avidity with which treated cells bind to bone. On the other hand, cortisol treatment was associated with stimulated protein and RNA synthesis, as evidenced by enhancement (P less than 0.001) of both [3H]leucine and [3H]uridine incorporation into treated cells. This association was also underscored by the observation that increased protein and RNA synthesis and enhanced mineral mobilization were inducible phenomena, i.e. phenomena that could be observed 48-72 h after cells were pretreated with cortisol. We conclude, therefore, that glucocorticoids can directly modify both the metabolism and the mineral-mobilizing activity of bone-resorbing cells.

Animals↗
PubMed1977

Zinc in ulcerative colitis: a therapeutic trial and report on plasma levels.

A double-blind controlled trial of oral zinc sulphate as adjuvant treatment in idiopathic ulcerative colitis or proctitis in relapse is reported. Fifty-one patients were treated, and the clinical and sigmoidoscopic improvement in the zinc treated patients was similar to that in patients receiving placebo. No difference was found between plasma zinc levels in a further 46 patients with idiopathic ulcerative colitis or proctitis and those obtained in a group of healthy controls.

Clinical Trials as Topic↗
PubMedDate not supplied

Falciparum malaria in a displaced Haitian population.

Falciparum malaria was a major problem among displaced Haitians in temporary camps at the US Naval Base, Guantanamo Bay, Cuba. From December 1991 to March 1992, 235 cases of unmixed falciparum malaria were diagnosed in the laboratory, giving a cumulative attack rate of 160 per 10 000 camp residents. All cases were successfully treated with oral chloroquine. Children under 16 years of age, and especially females, were at substantially higher risk of infection (attack rate 481/10 000 versus 278/ 10 000 for males in the same age range). Malaria attack rates by place of birth in Haiti were calculated per 10 000 people as Cayemite, 530; Baraderes, 375; Pestel, 285; Port Au Prince, 247; and La Gonave, 36. The time to onset of clinical malaria after embarking at the Naval Base ranged from one to 58 d. No malaria transmission was demonstrated in the migrant camp. A non-systematic survey showed a 1.7% prevalence (95% confidence interval +/- 1.9%) of falciparum malaria among asymptomatic residents. Health practitioners in areas that may receive Haitian migrants should plan to care for malaria and preventive medicine measures are indicated, as imported malaria could be transmitted in areas where competent vectors are indigenous.

Adolescent↗
PubMedDate not supplied

Risk factors for sexually-transmitted diseases among deployed U.S. military personnel.

BACKGROUND AND OBJECTIVES: Information regarding risk factors for STD transmission is needed to assist in designing and evaluating prevention and control programs for US military populations. GOAL OF THIS STUDY: To obtain STD risk factor data among deployed U.S. military personnel. STUDY DESIGN: A questionnaire survey was administered to military personnel deployed aboard ship for six months to South America, West Africa, and the Mediterranean during 1989-1991. RESULTS: Among 1,744 male subjects (mean age, 23 years; 71% white; 96% enlisted), 49% reported prior sexual contact with a prostitute and 22% reported a history of a STD before deployment. During the subsequent six-month deployment, 42% reported sexual contact with a prostitute, 10% reported inconsistent use of condoms, and 10% acquired a new STD. By logistic regression analysis, sexual contact with a prostitute during deployment was independently associated with young age, nonwhite race/ethnicity, and being unmarried or divorced; inconsistent use of condoms was associated with Hispanic race/ethnicity. CONCLUSION: These data indicate that deployed U.S. military personnel frequently engage in high-risk sexual behavior and that there is a continued need for comprehensive and culturally-sensitive STD prevention programs.

Adolescent↗