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Biomedical subjects

J Ricci

Publications and source records attributed to J Ricci.

At least 19 recordsLinked to original sources
PubMed2002

Interactions between MC3T3-E1 cells and textured Ti6Al4V surfaces.

This paper presents the results of an experimental study of the interactions between MC3T3-E1 (mouse calvarian) cells and textured Ti6Al4V surfaces, including surfaces produced by laser microgrooving; blasting with alumina particles; and polishing. The multiscale interactions between MC3T3-E1 cells and these textured surfaces are studied using a combination of optical scanning transmission electron microscopy and atomic force microscopy. The potential cytotoxic effects of microchemistry on cell-surface interactions also are considered in studies of cell spreading and orientation over 9-day periods. These studies show that cells on microgrooved Ti6Al4V geometries that are 8 or 12 microm deep undergo contact guidance and limited cell spreading. Similar contact guidance is observed on the surfaces of diamond-polished surfaces on which nanoscale grooves are formed due to the scratching that occurs during polishing. In contrast, random cell orientations are observed on alumina-blasted Ti6Al4V surfaces. The possible effects of surface topography are discussed for scar-tissue formation and improved cell-surface integration.

Alloys↗
PubMed2001

A new ultrasensitive assay for quantitation of HIV-1 RNA in plasma.

Nucleic acid-based diagnostic assays for the quantitation of plasma HIV-1 RNA levels are used to monitor disease progression and the response of patients to antiretroviral drug therapy. The LCx HIV RNA Quantitative Assay (Abbott Laboratories, North Chicago, IL) is an assay for the quantitation of HIV type 1 RNA in plasma that uses competitive reverse transcription PCR (RT-PCR) followed by Microparticle Enzyme Immunoassay, and includes an internal control for inhibition and RNA recovery, that is taken through the entire sample preparation procedure. The performance of the assay was assessed for 1 and 0.2 ml sample volumes. For a 1 ml sample volume, the lower limit of detection was found to be 50 copies/ml with a linear range from 50 to 1 million copies/ml. For a 0.2 ml sample volume, the lower limit of detection was found to be 178 copies/ml with a linear range from 178 to 5 million copies/ml. The assay is able to detect and quantitate HIV subtypes A-G and group O. LCx HIV RNA assay quantitation results are highly correlated to the standard and ultrasensitive Amplicor HIV-1 Monitor assay (Roche Molecular Systems) quantitation results. Assay performance is consistent with the use of this test for routine quantitation of HIV-1 RNA in plasma.

Cross Reactions↗
PubMed1997

Effects of low-intensity AC and/or DC electromagnetic fields on cell attachment and induction of apoptosis.

Rat tendon fibroblast (RTF) and rat bone marrow (RBM) osteoprogenitor cells were cultured and exposed to AC and/or DC magnetic fields in a triaxial Helmholtz coil in an incubator for up to 13 days. The AC fields were at 60 and 1000 Hz and up to 0.25 mT peak to peak, and the DC fields were up to 0.25 mT. At various combinations of field strengths and frequencies, AC and/or DC fields resulted in extensive detachment of preattached cells and prevented the normal attachment of cells not previously attached to substrates. In addition, the fields resulted in altered cell morphologies. When RTF and RBM cells were removed from the fields after several days of exposure, they partially reattached and assumed more normal morphologies. An additional set of experiments described in the Appendix corroborates these findings and also shows that low-frequency EMF also initiates apoptosis, i.e., programmed cell death, at the onset of cell detachment. Taken together, these results suggest that the electromagnetic fields result in significant alterations in cell metabolism and cytoskeleton structure. Further work is required to determine the relative effect of the electric and magnetic fields on these phenomena. The research has implications for understanding the role of fields in affecting bone healing in fracture nonunions, in cell detachment in cancer metastasis, and in the effect of EMF on organisms generally.

Animals↗
PubMed1996

Lack of neurotoxic effect of diethylpropion in crack-cocaine abusers.

Dopamine agonists have been used with some success in treating cocaine addiction. However, both cocaine and psychostimulants have been reported to produce neurotoxic effects. We evaluated the effect of the stimulant diethylpropion on cognitive performance in a double-blind, placebo-controlled trial. Forty-six abstinent crack-cocaine users received either placebo, 25-mg, 50-mg, or 75-mg doses of diethylpropion. Patients were tested at baseline and again after 9-14 days of medication. There were no differences between placebo and medication groups on any test, indicating that, within the time frame studied, diethylpropion does not produce neurotoxic effects that can be detected with standardized neuropsychological tests.

Adult↗
PubMed1995

Tricalcium phosphate and osteogenin: a bioactive onlay bone graft substitute.

The disadvantages of autogenous bone grafts has prompted a search for a dependable onlay bone graft substitute. A combination of tricalcium phosphate, a resorbable ceramic, and osteogenin, an osteoinductive protein, was evaluated as an onlay bone graft substitute in a rabbit calvarial model. Twenty-eight tricalcium phosphate implants (15 mm diameter x 5 mm; pore size, 100-200 microns) were divided into experimental and control groups and placed on the frontal bone of 14 adult New Zealand White rabbits. In the experimental animals, 185 micrograms of osteogenin was added to each implant. In the control animals, the implants were placed untreated. Implants were harvested at intervals of 1, 3, and 6 months, and evaluated using hematoxylin and eosin histology, microradiography, and histomorphometric scanning electron microscope backscatter image analysis. At 1 month there was minimal bone ingrowth and little tricalcium phosphate resorption in both the osteogenin-treated and control implants. At 3 months, both the osteogenin-treated and control implants showed a modest increase in bone ingrowth (8.85 percent versus 5.87 percent) and decrease in tricalcium phosphate (32.86 percent versus 37.08 percent). At 6 months, however, the osteogenin-treated implants showed a statistically significant increase in bone ingrowth (22.33 percent versus 6.96 percent; p = 0.000) and decrease in tricalcium phosphate (27.25 percent versus 37.80 percent; p = 0.004) compared with the control implants. The bone within the control implants was mostly woven at 6 months, whereas the osteogenin-treated implants contained predominantly mature lamellar bone with well-differentiated marrow. All implants maintained their original volume at each time interval studied. The tricalcium phosphate/osteogenin composite, having the advantage of maintaining its volume and being replaced by new bone as the tricalcium phosphate resorbs, may be applicable clinically as an onlay bone graft substitute.

Animals↗
PubMed1994

Phosphatidylazidothymidine and phosphatidyl-ddC: assessment of uptake in mouse lymphoid tissues and antiviral activities in human immunodeficiency virus-infected cells and in Rauscher leukemia virus-infected mice.

During the early stages of human immunodeficiency virus (HIV) infection, although symptoms are absent and viral replication in peripheral blood mononuclear cells is low, substantial levels of HIV replication can be documented in lymphoid tissue [G. Pantaleo, C. Graziosi, J.F. Demarest, L. Butini, M. Montroni, C.H. Fox, J.M. Orenstein, D.P. Kotler, and A.S. Fauci, Nature (London) 362:355-358, 1993, and J. Embretsen, M. Zupancic, J.L. Ribas, A. Burke, P. Racz, K. Tenner-Tacz, and A.T. Haase, Nature (London) 362:359-362, 1993]. This observation suggests that earlier treatment of HIV infection may be indicated and that strategies for enhancing drug targeting to the lymphoid tissue reservoris of HIV infection may be beneficial. To address this issue, we synthesized dioleoylphosphatidyl-ddC (DOP-ddC) and dipalmitoylphosphatidyl-3'-azido-3'-deoxythymidine (DPP-AZT), phospholipid prodrugs which form lipid bilayers and which are readily incorporated into liposomes. The anti-HIV activity of DOP-ddC was similar to that of ddC in HIV type 1-infected HT4-6C cells, but DPP-AZT was considerably less active than AZT in HT4-6C cells. Liposomes containing DOP-[3H]ddC or DPP-[3H]AZT administered intraperitoneally to mice produced greater levels of total radioactivity over time in plasma, spleen, and lymphoid tissue relative to the results with [3H]ddC and [3H]AZT, respectively. DPP-AZT administered intraperitoneally in liposomes as a single daily dose to mice infected with Rauscher leukemia virus prevented increased spleen weight and reverse transcriptase levels in serum with a dose-response roughly comparable to that of AZT given continuously in the drinking water. DOP-ddC, DPP-AZT, and lipid conjugates of other antiretroviral nucleosides may provide higher levels of drug over time in plasma and in lymph nodes and spleen, important reservoirs of HIV infection, and may represent an interesting alternative approach to antiviral nucleoside treatment of AIDS.

Animals↗
PubMed1991

Comparison of bovine collagen xenografts to autografts in the rabbit.

The use of bovine tendon as a xenograft material in humans is attractive because of its ready availability and favorable mechanical characteristics. Previous research has shown that the fibroblasts and some extracellular proteoglycans and glycoproteins, not the collagen matrix itself, in bovine tendon are primarily responsible for its antigenicity. Various attempts have been made to decrease the antigenicity of these grafts. A chloroform/methanol (CM) extraction procedure has been developed that selectively removes the fibroblasts from bovine tendon without destroying the collagen matrix. The mechanical, immunologic, and local host tissue responses to these grafts were compared to autografts and to untreated and glutaraldehyde-treated bovine tendon xenografts. The humoral immune response to a purified bovine Type I collagen product was also studied. The central two-thirds of a rabbit Achilles tendon were replaced with a reversed autograft or an experimental graft. Histologic examination of one- and two- week specimens showed an acute inflammatory response to all grafts. Untreated grafts stimulated a severe inflammatory response and were almost completely resorbed by two weeks. Glutaraldehyde-treated grafts were encapsulated. Cellular repopulation was minimal and inflammatory response was more persistent than in the autograft and CM groups. Inflammatory response to CM-treated grafts was similar to that of autografts. The CM grafts repopulated rapidly with host cells. The mechanical strength of CM grafts was equal to autograft controls at 12 weeks. The mechanical strength of untreated and glutaraldehyde-treated grafts was significantly lower. Measurement of the humoral immune response to these grafts was conducted in an independent group of animals using an enzyme-linked immunosorbent assay. A significant antibody response to untreated, glutaraldehyde-fixed, and CM-treated grafts was detected at 30 days. Antibody titers to glutaraldehyde-fixed and untreated grafts remained elevated at 60 and 90 days. In the CM group, antibody titers decreased to the level of autograft controls by 90 days. No significant antibody response was detected toward purified bovine Type I collagen.

Achilles Tendon↗
PubMed1990

Influence of magnesium sulfate-induced hypermagnesemia on the anion gap: role of hypersulfatemia.

Although hypermagnesemia purportedly lowers the anion gap (AG), we have shown previously that increases in the serum concentration of the unmeasured cation (UC) Mg due to therapeutic infusion of MgSO4 are not associated with AG reduction. To assess our hypothesis that increases in serum SO4 (unmeasured anion, UA) offset the effect of elevated serum Mg on the AG, we prospectively studied 11 patients receiving MgSO4 intravenously for toxemia of pregnancy. After 6 h of MgSO4 infusion, serum Mg increased by 2.1 +/- 0.2 (SE) mEq/l (p less than 0.001) without a significant decrease in the AG. Concomitantly, serum SO4 increased by 1.4 +/- 0.2 mEq/l. Comparison of the renal handling of SO4 versus Mg showed a higher fractional excretion of the former, probably accounting in part for the smaller increment of serum SO4 than of Mg. Comparison of the change in serum SO4 minus that of Mg indicated that, on the average, 70% of the observed 1.0 +/- 0.7 mEq/l reduction in AG was accounted for by the observed changes in the two pertinent unmeasured ions. A small decrement in serum Ca probably was a quantitatively minor factor tending to obviate a greater decrease in AG. We conclude that hypersulfatemia attenuates the reduction in AG that would otherwise accompany MgSO4-induced hypermagnesemia.

Acid-Base Equilibrium↗
PubMed1990

Psychosocial aspects of disability in children.

General psychosocial issues must be considered in facilitating the development of children with chronic illnesses and disabilities. A coping model and the developmental stages can be used as a framework to regard the impact of disabling conditions on children and the interventions that encourage psychosocial growth. Health professionals are encouraged to recognize the key role that they can play in promoting effective coping and growth for disabled children and members of their families and to incorporate psychosocial interventions into their practice.

Adaptation, Psychological↗
PubMed1989

[A comparison of cyclists' time records according to altitude and materials used].

The purpose of this study was to re-assess the energy cost of track cycling in order (a) to compare the one-hour world records at sea-level and altitude with classical bicycles or with modern bicycles including aerodynamic components, and (b) to estimate the optimal altitude to set a new one-hour world record. Energy cost of track cycling with a classical or aerodynamic bicycle was estimated according to the equation developed by di Prampero et al. (1979) using data from Davies (1980) for the rolling resistance coefficient and from Gross et al. (1983) for the aerodynamic resistance coefficient for each type of bicycle. When compared to the classical track-bicycle, and to the bicycle studied by di Prampero et al. (1979), the aerodynamic track-bicycle reduces the resistance coefficient by 11.7 and 16.9% respectively. According to these estimations the cyclists sustain 87-95% of maximal aerobic power over one hour, which is a likely value for a 60 min exercise period for top-level athletes. When the reduction of air density and of maximal aerobic power with altitude are taken into account, equivalences between performances achieved at different altitudes and with the two types of track-bicycles, can be computed. The best overall performance appears to be the current one-hour record at sea-level using an aerodynamic bicycle (Moser: 50.644 km.h-1). This performance is equivalent to 53.5 km.h-1 in Mexico City (2230 m), 54.4 km.h-1 in La Paz (3417 m) and 54.5 km.h-1 at 3843 m (472 mmHg), which would be the optimal altitude to set the record.

Air Pressure↗
PubMed1984

Prolonged fever associated with primary hyperparathyroidism.

A 36-year-old woman presented with hypercalcemia, hypercalciuria, elevated serum parathyroid hormone levels and prolonged fever. Surgical removal of the hyperplastic and adenomatous parathyroid glands led to reversal of the biochemical abnormalities as well as return of her temperature to normal.

Adenoma↗
PubMed1983

VO2max of cyclists from treadmill, bicycle ergometer and velodrome tests.

The purpose of this study was to measure the VO2max of trained cyclists on the treadmill (means +/- SD = 54.7 +/- 6.3 ml kg-1 min-1), while riding a bicycle on a velodrome track at 100 rpm (53.7 +/- 7.8) and on the bicycle ergometer at 60 rpm (62.4 +/- 8.1): VO2max beeing the highest in the latter case (p less than 0.05). The highest maximal HR, 188 +/- 6 beats min-1, was observed during the treadmill test, while estimates of 184 +/- 6 and 179 +/- 7 were obtained for the velodrome and the bicycle ergometer tests, respectively. No significant differences were observed in the blood lactate concentrations (treadmill: 10.35 +/- 4.01 bicycle ergometer: 10.25 +/- 2.29 velodrome: 10.95 +/- 1.51 mmol L-1. In conclusion, bicycle ergometer tests might not be specific enough to evaluate the ability of trained cyclists to perform an endurance or aerobic task on the track. Trained cyclists, as opposed to untrained ones, appear to achieve higher VO2max on the bicycle ergometer as compared to the treadmill.

Adolescent↗
PubMed1983

Effect of mechanical load in wound healing.

This study was designed to investigate the effect of sequentially increasing mechanical load on healing incisions. Full-thickness incisions were made on the back of a young domestic pig. During the period of fibroplasia, one of the incisions was mechanically loaded with a subcutaneous tissue expander. Mechanical and histological evaluations of mechanically loaded and control incision areas indicated that the mechanical stress encouraged healing and remodeling of dermal tissue.

Animals↗
PubMed1982

Skeletal muscle adaptation in adolescent boys: sprint and endurance training and detraining.

The purpose of the present study was to investigate the effects of 3-month sprint and endurance training programs on the vastus lateralis muscle fiber area and the activities of glycolytic (phosphofructokinase; PFK) and oxidative (succinate dehydrogenase; SDH) enzymes of adolescent boys. Enzyme activities were also determined after a subsequent 6-month detraining period. Endurance training resulted in significant increases in VO2max (58.4 to 64.3 ml . min-1 . kg-1), in ST and FTa fiber area (6.0 to 7.3 and 8.0 to 10.4 microns 2 x 10(3), respectively), and in SDH activity (6.4 to 9.1 IU). After detraining VO2max and SDH activity returned to pretraining levels. Sprint training resulted in a significant increase only in PFK activity (28.1 to 33.9 IU), which was also abolished in the detraining period. These data demonstrate that in adolescent boys skeletal muscle enzyme changes are specific to the mode of training and that they are similar in direction but different in magnitude to those found in adults.

Adolescent↗
PubMed1979

Phase II trial of cyclophosphamide, hexamethylmelamine, adriamycin, and cis-dichlorodiammineplatinum(II) combination chemotherapy in advanced ovarian carcinoma.

A monthly four-drug regimen of cyclophosphamide, adriamycin, and cis-dichlorodiammineplatinum(II), each given iv of Day 1, and hexamethylmelamine, given orally on Days 1--14 (CHAP), was administered to 39 women with advanced epithelial ovarian carcinoma who had previously failed alkylating agent therapy. Of 35 evaluable patients with a measurable disease parameter, seven (20%) achieved a clinical complete response and ten (29%) achieved a clinical partial response. The median duration of complete response is greater than 9 months and the median duration of partial response is 4 months. Ninety percent of the patients required dose adjustments because of profound leukopenia, thrombocytopenia, or gastrointestinal intolerance. CHAP is an active but toxic regimen in the management of advanced ovarian cancer. The toxicity encountered reflected the intensity of the drug schedule as well as the combined influences of advanced stage of disease, poor nutritional and performance status, and prior therapy. The efficacy of this CHAP regimen warrants a controlled trial compared to other active drug programs.

Alkylating Agents↗