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Biomedical subjects

R Gibbons

Publications and source records attributed to R Gibbons.

At least 37 records · Page 2Linked to original sources
PubMed1994

Time to reperfusion with direct coronary angioplasty and thrombolytic therapy in acute myocardial infarction.

An analysis was performed of the Mayo Clinic randomized trial of direct percutaneous transluminal coronary angioplasty and tissue-type plasminogen activator (t-PA) to determine the time required to achieve reperfusion with direct coronary angioplasty. Because patients in the Mayo trial assigned to t-PA did not undergo protocol coronary angiography, reperfusion rates from the Thrombolysis in Myocardial Infarction (TIMI) I trial in which patients underwent coronary angiography 30, 60 and 90 minutes after thrombolytic therapy were used for comparison. TIMI perfusion grade 2 or 3 flow in the infarct artery was considered to represent reperfusion after thrombolysis. In the 56 patients assigned to t-PA, the mean time from randomization to initiation of the t-PA infusion was 20 minutes. Twenty minutes were therefore added to the previously reported 30-, 60- and 90-minute reperfusion rates to express these in terms of time from randomization (50, 80 and 110 minutes). In the 48 patients who had direct angioplasty, the mean time from randomization to arrival in the cardiac catheterization laboratory was 45 minutes; it took a mean of 6 additional minutes for patients to be prepared and draped and arterial access obtained, and a mean of 27 additional minutes to complete angiography and achieve reperfusion. At 50, 80 and 110 minutes after randomization, the reperfusion rates for direct coronary angioplasty were 12, 54 and 83%, similar to previously reported TIMI reperfusion rates with t-PA (24, 57 and 71%, respectively, p = NS) but significantly greater at 80 and 110 minutes than was reported for streptokinase (8, 23 and 31%, respectively, p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1994

Interleukin-4 enhances murine bone marrow macrophage M-CSF receptor expression by a posttranscriptional mechanism.

Activated T-lymphocytes secrete interleukin-4 (IL-4), which has been shown to modulate a variety of monocyte activities requiring monocyte/macrophage colony-stimulating factor (M-CSF). To account for this interaction, we postulated that IL-4 acts on target cells by altering the expression of the M-CSF receptor (M-CSFr). To test this hypothesis, murine bone marrow macrophages were cultured under conditions that down-regulate M-CSFr and the effect of IL-4 on the reexpression of the receptor measured by binding of 125I-labeled M-CSF to the cells. The data show that incubation with IL-4 results in a dose-dependent, 2-3 x increase in M-CSFr with no change in binding affinity and a maximal effect on binding at about 12 h. This increase in M-CSFr is dependent upon new, specific protein synthesis as shown by the inhibitory action of cycloheximide, and gel analysis of radiolabeled, specific protein, immunoprecipitated with anti-M-CSFr antibody. Treatment with IL-4 does not stimulate M-CSFr mRNA expression but, consistent with enhanced receptor levels, does result in a heightened proliferative response to M-CSF. Thus, IL-4 affects M-CSF treated monocytic cells, at least in part, by altering the expression of M-CSFr.

Animals↗
PubMed1990

Serial measurement of integrated ultrasonic backscatter in human cardiac allografts for the recognition of acute rejection.

Cyclic variation of integrated ultrasonic backscatter (IB) was noninvasively measured in the septum and left ventricular posterior wall using a quantitative IB imaging system to assess the alterations in the acoustic properties of myocardium associated with acute cardiac allograft rejection. The study population consisted of 23 cardiac allograft recipients and 18 normal subjects. In each cardiac allograft recipient, one to eight (mean, four) IB studies were performed, each within 24 hours of right ventricular endomyocardial biopsy performed for rejection surveillance. The magnitude of the cyclic variation of IB in the posterior wall was 5.9 +/- 0.9 dB in normal subjects and 6.2 +/- 1.3 dB in the cardiac allograft recipients without previous or current histological evidence of acute rejection (n = 17, p = NS vs. normal subjects). The magnitude of cyclic variation of IB in the septum was 4.8 +/- 1.1 dB in normal subjects and 3.8 +/- 2.0 dB in the cardiac allograft recipients (n = 15, p = NS vs. normal subjects). A significant decrease in the septal IB measure was observed in cardiac allograft recipients with left ventricular hypertrophy (wall thickness of at least 13 mm) (2.6 +/- 1.7 dB, n = 8, p less than 0.05 vs. normal subjects). IB studies were done before and during moderate acute rejection in 11 recipients (14 episodes). During moderate acute cardiac rejection, the magnitude of the cyclic variation in IB decreased from 6.7 +/- 1.3 to 5.1 +/- 1.4 dB in the posterior wall (n = 14, p less than 0.05) and from 4.2 +/- 2.1 dB to 2.9 +/- 1.8 dB in the septum (n = 12, p less than 0.05). These data suggest 1) the magnitude of the cyclic variation in IB of the septum is different in cardiac allografts with cardiac hypertrophy and normal subjects, possibly reflecting regionally depressed myocardial contractile performance and 2) acute cardiac rejection in humans is accompanied by an alteration in the acoustic properties of the myocardium. This change is detectable by serial measurement of the magnitude of the cyclic variation in IB, both in the septum and in the posterior wall.

Echocardiography↗
PubMed1990

Left ventricular diastolic function. Doppler echocardiographic changes soon after cardiac transplantation.

In acute cardiac rejection, left ventricular diastolic function is altered, and a restrictive ventricular filling pattern occurs. Doppler echocardiographic indexes of mitral inflow have been proposed as sensitive markers of the rejection process. As rejection progresses, the restrictive ventricular filling pattern is reflected by a shortening of isovolumic relaxation time and mitral valve pressure half-time and by an increase in early transmitral filling velocity. Diastolic function is also compromised in the nonrejecting cardiac transplant recipient during the early postoperative period. This study examined the progression in Doppler-derived mitral filling indexes in 25 recent cardiac transplant recipients who demonstrated no histological evidence of transplant rejection. Isovolumic relaxation time, mitral valve pressure half-time, and early transmitral filling velocity were measured at postoperative weeks 1, 2, 4, and 6 on the day that surveillance right ventricular endomyocardial biopsies were performed. The initial indexes were comparable to previously described restrictive parameters and over the 6-week study period evolved into a nonrestrictive filling pattern. This evolution reflects a progressive improvement in postoperative diastolic function and a decrease in left heart filling pressures. None of the evaluated clinical characteristics, including preoperative pulmonary pressures, total ischemic time of the transplanted heart, cardiopulmonary bypass time, and age of the donor heart, correlated with this process. Given the increasing use of Doppler echocardiography as a means of screening for transplant rejection, it is important to have a thorough understanding of normal postoperative changes in left ventricular diastolic function.

Adult↗
PubMed1990

Time-related predictors of suicide in major affective disorder.

The authors studied 954 psychiatric patients with major affective disorders and found that nine clinical features were associated with suicide. Six of these--panic attacks, severe psychic anxiety, diminished concentration, global insomnia, moderate alcohol abuse, and severe loss of interest or pleasure (anhedonia)--were associated with suicide within 1 year, and three others--severe hopelessness, suicidal ideation, and history of previous suicide attempts--were associated with suicide occurring after 1 year. These findings draw attention to the importance of 1) standardized prospective data for studies of suicide, 2) assessment of short-term suicide risk factors, and 3) anxiety symptoms as modifiable suicide risk factors within a clinically relevant period.

Adolescent↗
PubMed1990

Recombinant IL-4 inhibits IL-6 synthesis by adherent peripheral blood cells in vitro.

IL-4 has been shown to participate in interregulatory networks with other cytokines including IL-2, IFN-gamma, IL-1 beta, and TNF-alpha. The ability of recombinant IL-4 (rIL-4) to modulate the synthesis and release of IL-6 was investigated in vitro. LPS-stimulated adherent cells (AC) from human peripheral blood secreted IL-6 as determined by ELISA and bioassay with the B9 hybridoma cell line. The secretion of IL-6 peaked between 12-16 h after LPS stimulation. The addition of rIL-4 inhibited LPS-induced IL-6 production measured at 8 h. The inhibitory effect of rIL-4 on IL-6 secretion was dose-dependent and occurred at doses as low as 0.001 U/ml (0.01 pg/ml). Recombinant IL-4 was added to the cultures for various periods and removed by aspiration of the medium and washing the cells. The subsequent LPS-induction of IL-6 secretion was reduced in cultures exposed to rIL-4 for as little as 5 minutes indicating that the effect of rIL-4 on the monocytes was rapid and irreversible. Northern blot analysis revealed that the effect of rIL4 on LPS-induced production of IL-6 by AC occurred at least in part at the level of transcription. In contrast, PMA-induced IL-6 gene transcription was not affected by rIL-4. These findings indicate that rIL-4 can regulate the synthesis of IL-6 by adherent peripheral blood mononuclear cells.

Acute-Phase Reaction↗
PubMed1989

Increasing pericardial effusion in cardiac transplant recipients.

Although pericardial effusion after cardiac surgery is frequent and usually benign, its etiology and prognosis after cardiac transplantation are unknown. During 1 year (1985-1986), 12 of our current transplant population (total, 189) developed moderate or large pericardial effusions confirmed by two-dimensional echocardiography. These effusions occurred within 1 month of transplantation in 10 patients and at 3 months and 4.5 years in the other two. Pericardiocentesis was performed because of clinical evidence of increasing effusions in eight patients, with demonstrable hemodynamic compromise secondary to tamponade in five. Pericardial fluid was sterile in all but one. Endomyocardial biopsy at the time of increasing effusion revealed moderate acute rejection in five patients, mild rejection in three, and no rejection in four. All three patients with mild rejection had moderate acute rejection on subsequent biopsy performed within 7 days. In two of the four with no rejection, repeat biopsy within 5 days showed moderate acute rejection; in a third, moderate rejection was present on biopsy performed 14 days later. Legionella dumoffii was isolated from the pericardial fluid of the fourth patient, whose subsequent biopsies never showed rejection. Three of the 12 patients developed progressive ventricular dysfunction sufficiently severe to require retransplantation. One patient died suddenly 12 months after transplantation, and autopsy examination revealed severe coronary artery disease. Two died of sepsis within 3 months of transplantation. Intense inflammatory infiltrates and thickening of the pericardium and epicardium were characteristically present in explanted and autopsy hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Platelet monoamine oxidase in alcoholism.

We studied platelet monamine oxidase (MAO) activity using 14C-tyramine as substrate in hospitalized alcoholic patients in the early phases of abstinence and in nonhospitalized normal control volunteers. Platelet MAO was determined in 75 patients (67 men, 8 women) with alcoholism and 123 normal control volunteers (52 men, 71 women). The platelet MAO activity in alcoholic patients was significantly lower than in normal control volunteers. We also observed that the mean platelet MAO activity in male alcoholics was significantly lower than in normal males. The analysis of platelet MAO in alcoholics revealed a mixture of two normal distributions. Alcoholic patients falling into the low MAO component were younger in age, with a lower age of onset of alcoholism, and had higher frequencies of family history of alcoholism. They thus resembled type II alcoholics described by other investigators. Platelet MAO may thus serve as a useful biological marker for subtyping alcoholism and identifying high-risk groups at an early stage. The findings of this study are consistent with previous reports of low platelet MAO activity in alcoholic patients.

Adult↗
PubMed1987

Catecholamine metabolism and disposition in healthy and depressed subjects.

Depressed patients as a group have been found to excrete greater amounts of catecholamines (CAs) and metabolites than healthy control subjects, but these differences were not uniform for all metabolites. Patients may differ from controls in the metabolism and/or disposition of CAs. We analyzed the suggested metabolic-dispositional differences by determining 24-hour urine values for norepinephrine (NE), epinephrine (E), normetanephrine (NM), metanephrine (M), vanillylmandelic acid (VMA), and 3-methoxy-4-hydroxyphenylglycol (MHPG). For each subject, we calculated ratios of CAs or metabolites to an estimate of CA synthesis and determined ratios of CAs and metabolites to each other based on a precursor-product paradigm. The results indicate that as a group, patients have modestly but significantly greater CA synthesis rates than controls; patients excrete disproportionately more NE and E and disproportionately less MHPG relative to estimated CA synthesis, as well as other metabolites, than do controls; in contrast to NE, E, and MHPG, the increased NM, M, and VMA excretion rates by patients are proportional to each other as well as to the increase in CA synthesis; and the differences in NE, E, and metabolite excretion in the patients as a group are due principally to unipolar rather than bipolar depressives. The differences would be expected if patients, relative to controls, released more NE and E into the circulation. These data indicate the need to measure several CAs and metabolites when evaluating differences between groups since the significance of any given metabolite value needs to be examined in the context of total CA and metabolite production and excretion.

Adult↗
PubMed1987

Self-efficacy and the control of anxious cognitions.

This study was designed to explore the possibility that Bandura's notion of self-efficacy can be applied to control over cognitions as well as behavior. Subjects were asked to complete questionnaires designed to measure their dental anxiety, the number of their negative self-statements about a dental appointment and their perceived ability to control these thoughts. Subjects with low anxiety claimed to experience fewer negative thoughts than those with moderate or high anxiety, and also to have more control over these thoughts. Subjects believed that the extent of their control would decline as the appointment approached in time, but least for the low anxiety group and most for the high anxiety group. Finally, differences in self-efficacy scores between anxiety groups were maintained when the number of negative thoughts was controlled for, but differences in negative thinking between anxiety levels were not maintained when self-efficacy was controlled for. These results suggest that anxiety is more closely related to thinking processes than content.

Adult↗
PubMed1987

Increased collagen synthesis and cross-link formation in the skin of rats exposed to vinyl chloride monomer.

Rats treated orally with vinyl chloride (30 mg/kg) daily for 2 years developed a syndrome which included thickening of the skin. Analysis of the skin showed a 26% increase in collagen deposition per unit weight, and a corresponding 30% increase in the levels of glycosylated lysine and hydroxylysine. There was a significant increase in the amounts of the labile borohydride reducible cross-links, such as the intermolecular hydroxylysinonorleucine (+31%) and histidinomerodesmosine (+42%) as well as the intramolecular allysine aldol cross-links (+17%). These results provide evidence that fibrosis of the skin is one of the pathological consequences of exposure to vinyl chloride.

Animals↗
PubMed1987

Adult esophageal candidiasis: a radiographic spectrum.

With the increasing use of cancer chemotherapy and organ transplantation requiring immunosuppressive therapy, and with the incidence of immunodeficiency states such as AIDS increasing, it is to be expected that candida esophagitis will occur with increasing frequency. Though fiberoptic endoscopy is a more specific and more sensitive approach to the diagnosis of candida esophagitis than barium esophagography, it is also more invasive, and many patients will continue to be examined radiologically, at least initially. The radiologist continues, therefore, to play a significant role in suggesting the diagnosis and it is incumbent on him to familiarize himself with the spectrum of common and unusual radiographic manifestations of this disease.

Adult↗
PubMed1987

Computed tomography of the rectum.

CT is an important diagnostic procedure in patients with suspected or known disease of the rectum. Knowledge of proper technique for CT of the rectum, as well as an understanding of normal pelvic anatomy, is essential to its effective use. CT can demonstrate the extent of perirectal and pararectal abnormalities detected on barium enema. While routine preoperative staging of rectal cancer is not justified, CT can be used to solve specific problems. Perhaps the most important role of rectal CT is in evaluating postoperative rectosigmoid cancer patients in an attempt to detect early asymptomatic recurrences and, thereby, prolong patient survival.

Abscess↗
PubMed1987

Clinical predictors of suicide in patients with major affective disorders: a controlled prospective study.

The authors report prospective uniform clinical data differentiating 25 patients who committed suicide from 929 patients who did not in a group of 954 patients with major affective disorder followed for an average of 4 years in the Collaborative Program on the Psychobiology of Depression. Eight (32%) of the suicides occurred within 6 months and 13 (52%) within 1 year of entry into the study. Hopelessness, loss of pleasure or interest, and mood cycling during the index episode differentiated the suicide group. Diagnostic subcategories, suicidal ideation at entry to the study, suicide attempts during current or past episodes, and medical severity of prior attempts did not differentiate the suicide group.

Adult↗
PubMed1986

Optimal cholangiographic technique for detecting bile duct stones.

Twenty-eight patients with proven bile duct stones were evaluated during either operative or T-tube cholangiography. Two radiographs were obtained for each patient without changing patient position between films. The first was performed with low peak kilovoltage (75-80 kVp) and 15% iodinated contrast medium and the second with high kVp (110) and 38% iodinated contrast. Seven radiologists evaluated the radiographs individually and in matched pairs for ductal filling, ductal penetration, motion unsharpness, overall quality, and stone detectability. The high-kVp radiographs were rated significantly better overall than the low-kVp studies (p less than 0.001) for all five criteria. In the second evaluation, which compared the pairs from the same patients, the 28 high-kVp radiographs were considered superior to the 28 low-kVp studies by the radiologists in almost two-thirds of the comparisons (ductal filling, 68%; penetration, 59%; less motion unsharpness, 65%; overall quality, 77%; stone detection, 62%). On the basis of the results of this study, high-kVp technique with full-strength contrast medium for operative and T-tube cholangiography is recommended.

Cholangiography↗