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Biomedical subjects

M Luna

Publications and source records attributed to M Luna.

At least 55 records · Page 3Linked to original sources
PubMed1995

Markers of primary mineralization are correlated with bone-bonding ability of titanium or stainless steel in vivo.

Critical events in the adaptation of osseous tissues to implant materials involve initial calcification of the newly synthesized bone. Previous studies indicated that bone-bonding but not nonbonding glass ceramics increase the matrix vesicle number, thereby compensating for delayed maturation of the extracellular organelles. The present study assessed whether this was also true for metal implants commonly used in orthopaedics and oral medicine. Bone-bonding titanium (Ti) or nonbonding stainless steel (SS) implants were placed in the right tibias of Sabra rats following ablation of the marrow. At 3, 6, 14, and 21 days postinjury, newly formed endosteal bone in the treated and contralateral limbs was removed and matrix vesicle-enriched membranes isolated. Alkaline phosphatase and phospholipase A2 specific activities and phosphatidylserine (PS) content were determined and compared with those of a nonsurgical control group. Results show that matrix vesicle alkaline phosphatase and phospholipase A2 activity and PS content was increased in the Ti-implanted limbs at 6 (peak), 14, and 21 days, although at levels less than observed in normal healing. Alkaline phosphatase activity remained elevated throughout the healing period. In contrast, these parameters were markedly inhibited in the SS-implanted limbs with respect to Ti or to normal healing. Both implants altered the systemic response associated with marrow ablation, but in an implant-specific manner. The results support the hypothesis that cells adjacent to bone-bonding materials can compensate for negative effects on primary mineralization during osteogenesis, whereas cells adjacent to nonbonding materials either do not compensate or are further depressed. The data support the use of the rat marrow ablation model as a tool for rapid, initial assessment of biomaterials in bone.

Alkaline Phosphatase↗
PubMed1995

Neuroendocrine regulation of adrenal gland and hypothalamus 5'deiodinase activity. II. Effects of splanchnicotomy and hypophysectomy.

This study analyzes the role of the autonomic nervous system, the pituitary gland, ACTH, dexamethasone (DEX), and thyroid hormones in the regulation of 5'deiodinase (5'D) in the hypothalamus (HP) and adrenal gland (AG) of the rat. 5'D activity was analyzed in rats under basal conditions (22 C) and during cold exposure (4 C, during 15, 30, 60, and 120 min). Several experimental groups were formed: intact animals (INT), unilateral (left) splanchnicotomized, sham splanchnicotomized, hypophysectomized (HPX), and sham hypophysectomized. Results in the hypothalamus were: 1) independent of the experimental group, the HP 5'D activity increased during the first 15-30 min of cold exposure; however, this increase was greater in operated animals than in INT rats; and 2) basal 5'D activity was increased in HPX rats and was also regulated by thyroid hormones. Results in the adrenal gland were: 1) INT rats exhibited a biphasic pattern of 5'D activation during cold stress (30 and 60 min of exposure); 2) the splanchnic nerve exerted a tonic-stimulatory effect on basal AG 5'D activity; 3) the denervated gland preserved its ability to respond to cold; 4) in INT animals DEX but not ACTH had a stimulatory effect on basal activity; 5) the high 5'D activity post-HPX was reverted to basal values by T4 and DEX administration; 6) SHAM-HPX also was followed by a large increase in basal 5'D activity, and 7) this hyperresponse was abolished by acute ACTH and DEX administration. In conclusion, our results demonstrate that the mechanisms that participate in the regulation and activation of 5'D in the adrenal gland and the hypothalamus are of a neuroendocrine nature. Also, in both organs, but mainly in the HP, 5'D activity is T4-dependent. In addition to the tonic-stimulatory influence conveyed by the splanchnic nerve, AG 5'D activity is influenced by thyroid hormones, glucocorticoids, and probably extrapituitary factors whose nature is unknown yet.

Adrenal Glands↗
PubMed1994

The relationship between the thrombotic and infectious complications of central venous catheters.

OBJECTIVES: To assess the frequency of thrombotic and infectious complications of long-term use of vascular catheters in cancer patients and to determine whether the two types of complication are related. DESIGN: Case series. SETTING: A 500-bed tertiary cancer center. PATIENTS: Seventy-two cancer patients. INTERVENTIONS: During a 16-month period, postmortem examinations of catheterized veins and contralateral uncatheterized veins were done on all patients with indwelling central venous catheters who met study criteria. MAIN OUTCOME MEASURES: Catheter-related septicemia determined by clinical and microbiological data as well as postmortem pathology; venous pathological changes such as mural hemorrhage, thrombosis, calcification, ulceration, and inflammation. RESULTS: Premortem clinical and microbiological data were obtained retrospectively on all patients. Pathological changes were noted in 35 catheterized veins (49%) compared with five contralateral control veins (9.2%) (P < .001). Mural thrombi were noted in 27 catheterized veins (38%) compared with only one contralateral control vein (1.4%) (P < .001). Other pathological changes consisted of four central venous catheter-related mural thrombi (5.6%) in the right atrium and four instances (5.6%) of nonbacterial thrombotic endocarditis, three involving the tricuspid and one the mitral valves. Seven patients had catheter-related septicemia. Of the 31 patients with mural thrombosis of the catheterized vein or right atrium, seven developed catheter-related septicemia, whereas none of the 41 patients with normal catheterized veins and atria developed catheter-related septicemia (P < .01). CONCLUSIONS: Thrombotic complications are common in catheterized veins and are often associated with catheter sepsis.

Adolescent↗
PubMed1994

Culture surfaces coated with various implant materials affect chondrocyte growth and metabolism.

The effect on chondrocyte metabolism of culture surfaces sputter-coated with various materials used for orthopaedic implants was studied and correlated with the stage of cartilage cell maturation. Confluent, fourth-passage chondrocytes from the costochondral resting zone and growth zone of rats were cultured for 6 or 9 days on 24-well plates sputter-coated with ultrathin films of titanium, titanium dioxide, aluminum oxide, zirconium oxide, and calcium phosphate (1.67:1). Corona-discharged tissue culture plastic served as the control. The effect of surface material was examined with regard to cell morphology; cell proliferation (cell number) and DNA synthesis ([3H]thymidine incorporation); RNA synthesis ([3H]uridine incorporation); collagenase-digestible protein, noncollagenase-digestible protein, and percentage of collagen production; and alkaline phosphatase-specific activity, both in the cell layer and in trypsinized chondrocytes. Cell morphology was dependent on surface material; only cells cultured on titanium had an appearance similar to that of cells cultured on plastic. While titanium or titanium dioxide surfaces had no effect on cell number or [3H]thymidine incorporation, aluminum oxide, calcium phosphate, and zirconium oxide surfaces inhibited both parameters. Cells cultured on aluminum oxide, calcium phosphate, zirconium oxide, and titanium dioxide exhibited decreased collagenase-digestible protein, noncollagenase-digestible protein, and percentage of collagen production, but [3H]uridine incorporation was decreased only in those chondrocytes cultured on aluminum oxide, calcium phosphate, or zirconium oxide. Chondrocytes cultured on titanium had greater alkaline phosphatase-specific activity than did cells cultured on plastic, but the incorporation of [3H]uridine and production of collagenase-digestible protein, noncollagenase-digestible protein, and percentage of collagen was comparable. The response of chondrocytes from the growth zone and resting zone to culture surface was comparable, differing primarily in magnitude. Cell maturation-dependent effects were evident when enzyme activity in trypsinized and scraped cells was compared. These results indicate that different surface materials affect chondrocyte metabolism and phenotypic expression in vitro and suggest that implant materials may modulate the phenotypic expression of cells in vivo.

Alkaline Phosphatase↗
PubMed1994

Thiotepa, busulfan, and cyclophosphamide as a preparative regimen for marrow transplantation: risk factors for early regimen-related toxicity.

One hundred twenty-seven adults with advanced hematologic malignancies received thiotepa 450-750 mg/m2, busulfan 10 or 12 mg/kg, and cyclophosphamide 120 or 150 mg/kg as a preparative regimen for autologous (86 patients) or allogeneic (41 patients) marrow transplantation. Early regimen-related toxicity (RRT) was scored according to the Seattle toxicity grading system. Grade 1-4 RRT occurred in 94% of the patients. Grade 3-4 RRT was noted in 19 patients (9% of the autologous and 27% of the allogeneic marrow recipients) and included 6% hepatic, 5% pulmonary, 3% renal, 2% mucosal, 2% bladder, 2% cardiac, and 1% CNS toxicity at the grade 3 or 4 level. No patient experienced life-threatening or fatal gastrointestinal or cutaneous toxicity. A stepwise logistic regression analysis suggested that the higher busulfan dose, Zubrod performance status of 2 or 3, and ten or more previous cycles of chemotherapy were factors predictive of grade 3-4 RRT. The regimen-related mortality for all patients was 8% (95% Cl 4-14%). The incidence and spectrum of RRT for this novel drug combination are similar to those reported for the standard preparative regimens. Heavily pretreated patients with poor performance status receiving the higher busulfan dose have a higher incidence of severe or fatal RRT.

Adult↗
PubMed1994

Leukemia cutis in acute promyelocytic leukemia: report of three cases after treatment with all-trans retinoic acid.

Acute promyelocytic leukemia (APL) is a distinct form of acute myelogenous leukemia characterized by an abundant number of abnormal progranulocytes, a severe coagulopathy and a distinct chromosomal abnormality t(15;17). Recently all-trans retinoic acid (ATRA) has been shown to induce complete remissions in APL. We report three patients with APL treated with ATRA, who at the time of relapse had leukemic infiltration of the skin (leukemia cutis), a manifestation which we had not seen previously in over 60 patients with APL treated with chemotherapy alone and has only rarely been reported in the literature. We hypothesize that ATRA treatment for APL may be associated with an increased incidence of extramedullary disease at the time of relapse, which may be mediated through an increase in expression of adhesion molecules. Careful observation for extramedullary relapses in patients treated with ATRA for APL will be needed to confirm our observation.

Adult↗
PubMed1994

Evaluation of anti-CD5 ricin A chain immunoconjugate for prevention of acute graft-vs.-host disease after HLA-identical marrow transplantation.

Anti-CD5 ricin A chain immunoconjugate (XZ-CD5) is an immunotoxin that inhibits proliferative and cytotoxic responses to alloantigen in vitro and has activity in the treatment of acute graft-vs.-host disease (GVHD). To determine if XZ-CD5 could be used to prevent acute GVHD, 11 adult recipients of HLA-identical allogeneic marrow received XZ-CD5 0.1 mg kg-1 day-1 intravenously with high-dose methyl-prednisolone for 10, 14 or 17 doses early post-transplant. Six additional patients received 17 doses of XZ-CD5 and cyclosporine (CSA). All patients engrafted. Severe capillary leak syndrome was the most common serious toxicity and occurred more frequently in patients receiving CSA (5/5 vs. 3/11, P = 0.03). All evaluable patients developed acute GVHD; 88% had grade II-IV GVHD. Flow cytometric analysis demonstrated a substantial number of circulating CD5+ and CD3+ lymphocytes during and early after administration of XZ-CD5. These results suggest that the immunotoxin did not eliminate alloreactive T cells in this setting.

Acute Disease↗
PubMed1994

A phase I-II study of high-dose thiotepa, busulfan and cyclophosphamide as a preparative regimen for allogeneic marrow transplantation.

Thirty adults with hematologic malignancies at high-risk for relapse were treated on a phase I-II study of high-dose thiotepa, busulfan (BU) and cyclophosphamide (CY) as the preparative regimen for allogeneic marrow transplantation. Cyclosporine and methylprednisolone or anti-CD5 ricin A chain immunoconjugate were used as graft-versus-host disease prophylaxis. Filgrastim was given from day 1 to enhance engraftment. Median follow-up time is 16 months (range 9-29 months). Grades III-IV regimen-related toxicity occurred in 5 (26%) of 19 patients treated with thiotepa 250 mg/m2 x 3, BU 1 mg/kg x 12 and CY 60 mg/kg x 2 and this was considered the maximal tolerated dose-schedule. Stomatitis and hepatoxicity were dose-limiting. All patients engrafted and had complete donor chimerism. The actuarial rate of acute graft-versus-host disease was 71% (95% CI 62-80%). The relapse rate at 1 year was 38% (95% CI 25-50%) and the actuarial survival at 1 year was 30% (95% CI 22-38%). The combination of thiotepa, BU and CY is tolerable as a preparative regimen for allogeneic marrow transplantation.

Adolescent↗
PubMed1994

Acanthamoeba meningoencephalitis after bone marrow transplantation.

Two patients presented with fever and nodular pulmonary infiltrates 9 and 6 months after marrow transplantation for leukemia. The second patient also had painful subcutaneous nodules that subsequently ulcerated. Both had a history of sinusitis and both had recently been treated with corticosteroids. During treatment with antibacterial and antifungal antibiotics, they developed rapid mental deterioration, coma and/or seizures. CT findings included hydrocephalus with extensive cortical and periventricular hypodensities in the first patient, and hydrocephalus with a cerebellar hemorrhage and edema in the second patient. Cerebrospinal fluid had a low glucose and elevated protein levels with few erythrocytes and little or no pleocytosis. Despite therapy with broad-spectrum antibiotics, including coverage for opportunistic infections, both patients died. Autopsy revealed Acanthamoeba species causing necrotizing meningoencephalitis, pneumonitis and adrenalitis in the first patient and causing necrotizing meningoencephalitis and dermatitis in the second patient. While these are the only reported cases of disseminated Acanthamoeba infection in marrow transplant recipients, a review of the literature suggests that this organism may be a new cause of opportunistic infections.

Acanthamoeba↗
PubMed1994

Ganciclovir three times per week is not adequate to prevent cytomegalovirus reactivation after T cell-depleted marrow transplantation.

To determine if ganciclovir given three times per week post-transplant is tolerable and effective for prevention of cytomegalovirus (CMV) infection in recipients of T cell-depleted marrow from related or unrelated donors, we have used ganciclovir 2.5 mg/kg iv three times daily on days -8 to -2 and 5 or 6 mg/kg iv 3 times per week from engraftment to day 100 as CMV prophylaxis for 51 adults who were CMV-seropositive or had seropositive donors. All patients received iv immunoglobulin 500 mg/kg weekly and CMV-negative or filtered blood products. Blood and urine were tested for CMV at weekly intervals through day 100. All patients received ganciclovir pre-transplant. Ten patients did not receive ganciclovir post-transplant (5 deaths, 3 graft failure, 1 renal failure, 1 required foscarnet). The median time to initiation of ganciclovir was 27 days (range 17-59 days) and the median duration of therapy was 51 days (range 5-83 range). Twelve patients had dose reductions (3 neutropenia and 9 renal insufficiency). Seven patients died before day 100, 2 had indications to change to foscarnet, 15 discontinued ganciclovir because of neutropenia and 17 completed the full ganciclovir course through day 100. G- or GM-CSF was given to 29 patients with neutrophils < 1.5 x 10(9)/l (10 had neutrophils < 0.5 x 10(9)/l) but only 12 of them could continue full-dose ganciclovir. Bacteremia occurred in 12 of the neutropenic patients. At day 120, the actuarial rate of CMV infection was 58% (95% CI 42-74%) and that of CMV disease was 36% (95% CI 21-51%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Prevention by Tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate) of vanadate-induced developmental toxicity in mice.

Vanadate is embryotoxic and fetotoxic in golden hamsters, mice and rats. Tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate), a chelating agent widely used in analytical chemistry, is an effective antidote in the treatment of oral or parenteral vanadate poisoning. The present study evaluated the effect of administration of Tiron on sodium metavanadate (NaVO3)-induced developmental toxicity in mice. NaVO3 (25 mg/kg, i.p.) was injected on day 12 of gestation, whereas Tiron was injected subcutaneously at 0, 24, 48, and 72 hr after NaVO3 administration. Tiron effectiveness was assessed at dosage levels of 0, 250, 500, and 1,000 mg/kg. Cesarean sections were performed on gestation day 18. All live fetuses were examined for external, internal, and skeletal malformations and variations. Amelioration by Tiron of NaVO3 developmental toxicity was evidenced by a significant decrease in the number of resorbed fetuses, an increase in the mean fetal weight, and a reduction in the incidence of the skeletal variations caused by NaVO3. According to these results, Tiron offers encouragement with regard to its therapeutic potential for pregnant women exposed to vanadate. However, further investigations, including the effect of increasing the time interval between acute vanadate exposure and initiation of Tiron therapy, are required.

1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium ↗
PubMed1993

Parainfluenza virus infection in adult bone marrow transplant recipients.

The clinical course of parainfluenza virus infection occurring in 8 of 265 (3%) adult bone marrow transplant recipients during 1991 was reviewed. Parainfluenza virus type 3 was isolated from all eight patients. The clinical course ranged from self-limited upper respiratory tract infections (2 patients) to severe lower respiratory tract disease (6 patients) associated with a 50% mortality. This study highlights the important role of community respiratory viruses such as parainfluenza virus in the etiology of pneumonia in immunocompromised adults.

Adult↗
PubMed1992

Adenoid cystic carcinoma of the palate.

We reviewed the clinical records of 41 patients who received definitive treatment for adenoid cystic carcinoma arising from the palate. Tumors were divided into three categories depending on local extension and pattern of growth. Surgery, either alone or in combination with post-operative radiation therapy, yielded satisfactory local regional control of the cancer. Patients who had adenoid cystic carcinoma with diffuse microscopic spread into adjacent tissues had the highest propensity for the development of distant metastases.

Adult↗