Search PubMed⌕ Search

Biomedical subjects

R C Robbins

Publications and source records attributed to R C Robbins.

At least 109 records · Page 6Linked to original sources
PubMed1988

Cardiac valve replacement in children: a twenty-year series.

Ninety-four children ranging from 3 months to 19 years of age underwent cardiac valve replacement at Columbia Presbyterian Medical Center from 1965 to 1985. The overall operative mortality was 12%, but mortality was higher among patients less than 2 years of age, patients who had had previous cardiac operations, and patients requiring double-valve replacement. Seven of 11 patients who received mechanical valves and no anticoagulation experienced major thromboembolic events. An episode of gastrointestinal hemorrhage that was easily controlled represents the only bleeding complication in the entire series. Valve replacement in children continues to be a high-risk procedure, and efforts to preserve native valve function should be attempted when technically feasible. Our data also suggest that anticoagulation can be safely accomplished in the pediatric age group and should be employed in patients requiring placement of a mechanical prosthesis, especially in the mitral position.

Adolescent↗
PubMed1988

Ingestion of grapefruit lowers elevated hematocrits in human subjects.

This study was based on in vitro observations that naringin isolated from grapefruit induced red cell aggregation and evidence that clumped red cells are removed from the circulation by phagocytosis. The effect on hematocrits of adding grapefruit to the daily diet was determined using 36 human subjects (12 F, 24 M) over a 42-day study. The hematocrits ranged from 36.5 to 55.8% at the start and 38.8% to 49.2% at the end of the study. There was a differential effect on the hematocrit. The largest decreases occurred at the highest hematocrits and the effect decreased on the intermediate hematocrits; however, the low hematocrits increased. There was no significant difference between ingesting 1/2 or 1 grapefruit per day but a decrease in hematocrit due to ingestion of grapefruit was statistically significant at the p less than 0.01 level.

Adult↗
PubMed1988

Flavones in citrus exhibit antiadhesive action on platelets.

Two methoxylated flavones isolated from citrus, sinensetin (5 methoxyls) and heptamethoxy flavone (7 methoxyls), were compared in vitro with nobiletin for antiadhesive activity on rat platelets. Nobiletin (a hexamethoxyflavone also isolated from citrus) has been previously shown by several workers to have antiadhesive and antithrombogenic activity. The penta- and heptamethoxylated flavones exhibited anti-adhesive activity similar to that of nobiletin. However, activity did not parallel number of methoxyl groups which appear to indicate some degree of specificity between flavone structure and antiadhesive activity on platelets.

Animals↗
PubMed1987

Elevated pulmonary vascular resistance and cardiac transplantation.

Severe elevation of pulmonary vascular resistance has been considered a contraindication to cardiac transplantation. Most centers exclude patients with pulmonary vascular resistance greater than 6 Wood units. Wood units, however, do not correct for variations in body size and therefore may not be the best measure for use in comparison of patients. We performed a retrospective analysis of 82 cardiac transplant recipients and compared preoperative pulmonary vascular resistance (PVR) calculated in two ways to the incidence of right ventricular failure and death. Our data show that the PVR index unit (PVRI) identifies those patients that are at risk for right heart failure better than the Wood unit, which does not correct for body size. Four patients died of right heart failure with resistance less than 6 Wood units, but had PVRI greater than 6 units. High resistance is not an absolute contraindication to cardiac transplantation; 28 of 33 patients operated on with a PVRI greater than 6 survived. The degree of elevation of PVR did not correlate with survival. Ten of 12 patients with a PVRI greater than 9 survived. Testing with nitroprusside at cardiac catheterization was helpful in determining reversibility of pulmonary vascular obstruction. No patients with a PVRI less than 6 developed right heart failure.

Adolescent↗
PubMed1987

Cardiac xenotransplantation in primates.

Successful cardiac xenotransplantation would alleviate the severe shortage of donor organs that presently limits the availability of cardiac transplantation. Early attempts at human xenotransplantation achieved minimal success. However, the effectiveness of cyclosporine in nonhuman xenotransplant models has received little experimental investigation. We have therefore studied the effect of cyclosporine-based immunosuppression in primate cardiac xenograft models using cynomolgus monkey donors and baboon recipients. Donor hearts were transplanted heterotopically into the necks of recipients or in the orthotopic position. Recipients were treated with no immunosuppression (controls), cyclosporine and steroids, or cyclosporine, steroids, azathioprine, and antithymocyte globulin. Statistically significant prolongation of graft survival compared to the control group was observed in the heterotopic groups. Mean survival time of the cyclosporine-treated and steroid-treated heterotopic grafts was 61 days compared to 6 days for grafts in the control group (p = 0.01); the addition of azathioprine and antithymocyte globulin yielded a mean survival of 84 days (p less than 0.01). No significant increase in graft survival was noted in the orthotopic groups treated with either immunosuppressive regimen. Although long-term use of human xenografts as an alternative for heart replacement is not supported by these data, further investigation of the orthotopic model is clearly justified.

Animals↗
PubMed1978

Effect of ratio of enzymes to substrate on amino acid patterns released from proteins in vitro.

Using an in vitro procedure, with both plant (gluten and edestin) and animal proteins (egg white and casein) as ratio of protein substrate to enzymes (pepsin, trypsin, erepsin) was increased in progressive stages, there was a change in the amino acids released; the proportions of some amino acids progressively increased, others progressively decreased while still others remained constant. The pattern of amino acids released was distinct for each protein and as substrate increased relative to enzymes, certain amino acids essential for the human increased with some proteins and decreased with others which suggests nutritional implications. The variations in amino acids released with changes in ratio of substrate to enzymes was not a random effect but an apparent orderly process. The phenomenon is termed "variable ratio effect".

Amino Acids↗
PubMed1978

Effect of enzyme combination and dialysis on amino acid patterns released from proteins.

Different combinations of gastrointestinal enzymes and dialysis altered amino acid yield and patterns released from proteins but did not negate the "variable ratio effect". That is, as substrate was increased relative to enzymes some amino acids increased, others decreased while still others were unchanged as a function of total quantity released. None of the enzymatic treatments degraded proteins proportional to amino acid composition.

Amino Acids↗
PubMed1977

Stabilization of flow properties of blood with phenylbenzo-gama-pyrone derivatives (flavonoids).

An investigation conducted on erythrocytes suspension in plasma revealed an instability caused by apparent sensitivity of erythrocytes to aggregation due to slight changes in normal plasma constituents. There is evidence that low level intravascular aggregation and so-called normal erythrocyte sedimentation rate (ESR) of apparently healthy people may be caused by undue sensitivity of erythrocytes to aggregation by plasma constituents as they vary within accepted normal ranges. Certain flavones, particularly methoxylated compounds, which may occur in the diet, increase resistance of erythrocytes to aggregation by shifts in plasma constituents. The stabilizing and apparent regulatory action of flavonoids on parameters important in the rheology of blood supports the concept that these compounds are necessary in the diet.

ABO Blood-Group System↗
PubMed1976

Regulatory action of phenylbenzo-gamma-pyrone (PBP) derivatives on blood constituents affecting rheology in patients with coronary heart disease (CHD).

In patients with CHD the hematological and serum chemical profiles showed significantly elevated (P less than 0.05) serum cholesterols, highly significantly increased hematocrits (P less than 0.025 to P less than 0.001) and the erythrocyte sedimentation rates (ESR) (red cell aggregation) along with several blood constituents causal of erythrocyte aggregation were significantly elevated (P less than 0.05 to P less than 0.025). Thus, major defects were elevated serum cholesterol, increased blood viscosity and reduced tissue perfusion which present evidence implicates as interactive factors in the pathogenesis of CHD. Methoxylated PBP derivatives exhibited a highly significant antiadhesive action (P less than 0.001) on erythrocytes and certain PBP hydroxylated glycosides showed a significant accelerating (P less than 0.05) action on erythrocyte aggregation which causes sequestration and reduced erythrocyte concentration. Thus, the PBP derivatives exert an apparent regulatory action on erythrocyte aggregation and concentration, two major factors affecting blood viscosity and flow. The PBP compounds occur in plants and are found in certain foods which suggests dietary control of the blood high viscosity syndrome.

Aged↗
PubMed1975

Action in human blood of methoxylated flavones which confer disease resistance on both plants and animals: concept of a dietary conditioned mechanism of defense against disease-1,2.

The antiadhesive action of methoxylated flavones on cells in blood of hospitalized patients was significantly associated with calcium, probably at membrane interfaces. This action is consistent with the role of calcium in cell aggregation and disaggregation. These and other recent findings suggest the body has a capacity for an environmentally related dietary conditioned, resistance to disease. The concept is based on evidence that phenylbenzo-gamma-pyrone derivatives, methyoxylated flavonoids and related compounds, synthesized in plants with antiviral, antifungal and bacteriostatic action may be absorbed into the body and attach reversibly to blood cells. In the body, in addition to any potential action against pathogens, certain of these compounds potentiate enzymes which detoxify carcinogenic hydrocarbons, exhibit antiinflammatory activity, exert antiadhesive action on blood cells and show antithrombogenic activity. The evidence indicates that of this class of compounds, a few are broad spectrum in their action, while several others possess one or another of the above functions. Also, some compounds are active in practically all subjects while others are active only in some patients. Specificities appear to be involved in action of the compounds on both pathogens and body processes.

Alkaline Phosphatase↗
PubMed1975

Mechanisms of reversed flavonoid action on blood cells: significance in thromboembolism.

An investigation was conducted on reversal of flavonoid action on erythrocyte aggregation and sedimentation (ESR) in blood from hospitalized patients. Nine compounds were tested. The flavonoids inhibited the ESR in some patients, showed no effect in others and accelerated the ESR in still other patients. With normal ratios of plasma proteins and packed cell volumes (PCV) of 40 vol % or lower the flavonoids inhibited the ESR, but they reversed their action and accelerated the ESR with increased PCV, alteration of plasma proteins, increased calcium and decreased phosphorus; conditions which apparently decreased intercellular distance enabling flavonoids to bridge between erythrocytes similar to antibodies and increase aggregation and sedimentation. The PCV of 156 patients, 60 males and 96 females, average 42 vol % for males and 39 vol % for females. Among these patients 27 had PCV's above 45 vol % and 63.9% of this group (ac PCV 49.5) had experiencedrecent thrombotic episodes compared to only 3.4% for patients with PCV's below 45 vol % (av PCV 41.0). These data point to hazards of PCV's that are considerably above the range of maximum oxygen transport of 40 to 42 vol %. Since the liver and spleen remove clumped cells from the circulation, present evidence indicates flavonoids via their aggregating action at high PCV's may function as regulators acting to maintain tissue perfusion via their antiadhesive action on blood cells and adjustment of ratio of cells to fluid volume of the blood.

Blood Proteins↗