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Biomedical subjects

R C Chiu

Publications and source records attributed to R C Chiu.

At least 127 records · Page 7Linked to original sources
PubMed1984

Clinical impact of intravenous hyperalimentation on esophageal carcinoma: is it worthwhile?

The coexistence of malignancy and dysphagia makes nutritional deprivation especially serious in patients with carcinoma of the esophagus. Intravenous hyperalimentation (IVH) is often given and should be of particular value in these patients. Sixty-four patients with carcinoma of the esophagus seen between January, 1975, and February, 1982, were studied retrospectively during their first hospitalization for the disease. Thirty-seven patients received IVH, and 27 did not. There were no significant differences at the time of admission to the hospital between the two groups with respect to age, sex, pathological status, and location of the carcinoma. Also, there was no difference in the incidence of hypoalbuminemia (less than 3 gm/dl) or lymphocytopenia (less than 1,500/mm3). More patients in the IVH group underwent surgical resection of the esophagus. Surgical intervention did not significantly influence hospital mortality. The IVH therapy reduced weight loss (p less than 0.05), but was associated with an increased incidence of pulmonary sepsis (p less than 0.05) and longer hospital stay. The incidence of hypoalbuminemia and lymphocytopenia increased between admission and the end of hospitalization, but it did not significantly differ between the groups. Thus, one cannot assume the effectiveness of IVH in this clinical setting, as its value was not demonstrated in this retrospective series. A prospective randomized study is warranted in view of the high cost and the doubtful clinical impact of an IVH regimen in patients with carcinoma of the esophagus.

Adenocarcinoma↗
PubMed1984

Pulmonary bacterial clearance and alveolar macrophage function in septic shock lung.

The association between the pulmonary bacterial clearance and the development of septic shock lung has been demonstrated in porcine and canine experimental models. In order to elucidate the role of the pulmonary reticuloendothelial system in bacterial clearance, the functions of alveolar macrophages (AM) obtained by bronchopulmonary lavage were studied. Five piglets were infused intravenously with Pseudomonas aeruginosa labeled with tritiated thymidine at 3 to 6 X 10(8) CFU/kg/min. Septic shock and manifestations like those of the adult respiratory distress syndrome developed within 1 h, and the pigs died within 2 to 3 h. Pulmonary bacterial clearance was 93% initially, and progressively decreased to 29%, as Pao2 decreased and lung water increased. The number of bacteria in the serial lung biopsy specimens increased steadily, although the distribution was not homogeneous. Differential centrifugations, repeated washings, and scintillation countings of the lavage fluid showed that in vivo AM phagocytosis was nil, despite the abundant bacteria found in the lavage fluid. However, when these AM were washed and tested in vitro in the presence of optimal concentrations of opsonin and oxygen, their phagocytic capability was well preserved, and was not significantly different from that of prebacterial infusion baseline values. It is concluded that in the septic shock lung, the lung clears bacteria not primarily by AM uptake but by other mechanisms, such as mechanical leakage into the pulmonary space, or by pulmonary intravascular leukocyte uptake. The apparent AM dysfunction in vivo is not intrinsic, and is likely to be caused by microenvironmental factors, such as lack of adequate opsonin and oxygen.

Animals↗
PubMed1984

Percutaneous transluminal angioplasty of iliac arteries: the importance of functional studies.

Results of percutaneous transluminal angioplasty of 60 iliac arteries are presented, with a follow-up of 3 to 12 months. The patency rate at 1 year was 95% using the thigh-brachial index as the criterion and 86% with the ankle-brachial index. Study of the patients with an exercise test component improved the sensitivity of the evaluation, demonstrating that both indices tend to underestimate the functional improvement. The authors propose a simple, cost-effective way for practitioners to follow-up their patients after percutaneous transluminal angioplasty.

Angioplasty, Balloon↗
PubMed1984

Operative myocardial protection: does an elevated level of creatine phosphokinase-MB isoenzyme always indicate myocardial necrosis?

Creatine phosphokinase-MB isoenzyme appears in the serum of virtually all patients who have undergone cardiac operations, but whether it represents myocardial cellular necrosis remains controversial. In 17 adult patients who underwent coronary artery bypass grafting or valve replacement, serial determinations of the serum levels of creatine phosphokinase-MB isoenzyme, ultrastructural studies of left ventricular myocardium before aortic cross-clamping and 10 minutes after reperfusion and postoperative electrocardiographic recordings were undertaken. The isoenzyme was detected in all patients; those having valve replacement had higher peak values than those who underwent coronary artery bypass grafting. No correlation was found between the duration of aortic cross-clamping and the peak level of isoenzyme after reperfusion. In spite of appreciable isoenzyme release from the myocardium, all the specimens obtained from this series of patients after reperfusion showed myocardial ultrastructural changes indicative of mild to moderate ischemic damage, considered to be reversible according to the criteria described by Jennings and Schaper. Except for one new Q wave, electrocardiographic changes in this series were nonspecific and transient. It is postulated that when sufficient myocardial mass is involved, such as in global ischemia during cardiac surgery, the MB isoenzyme of creatine phosphokinase leaked from reversibly damaged myocytes may become detectable and elevated in the serum. Thus, although the isoenzyme remains a sensitive indicator of myocardial protection, its presence does not necessarily indicate irreversible damage and myocardial necrosis.

Adult↗
PubMed1984

Depression and delayed recovery of alveolar macrophage function during starvation and refeeding.

Malnourished patients are particularly vulnerable to pulmonary infection. In this study using a rat model, starvation was found to depress significantly the phagocytic capability of pulmonary alveolar macrophages which play important roles in the local cellular defenses of the lung. Intracellular bactericidal function of the alveolar macrophages was not affected. On refeeding, in spite of the rats regaining their body weights and the recuperation of certain systemic immune indexes, there was a delay in the recovery of alveolar macrophage phagocytic function.

Animals↗
PubMed1984

Synchronously stimulated skeletal muscle graft for myocardial repair. An experimental study.

We studied the feasibility of augmentation of impaired myocardium with synchronously paced skeletal muscle grafts. The short contractile period of skeletal muscle required development of a new stimulator to ensure that the pedicle graft contraction would simulate that of the myocardium. In four dogs each, rectus and diaphragmatic muscles were wrapped around a balloon and electrically stimulated in synchrony with the electrocardiogram, varying stimulation currents and frequency of discharge during systole. For this purpose, a prototype hybrid stimulator was developed which senses the cardiac R wave and modulates the electrical output to the skeletal muscle by delivering a train of impulses of varying frequencies within the systolic intervals. The contraction characteristics in response to such stimulation were similar in rectus and diaphragmatic muscles, but the former developed higher maximum tensions because of the greater muscle bulk. Square-wave output was found to be more effective than sine-wave stimulation, and a single stimulating electrical pulse of 40 msec duration produced a maximum tension of 60 mm Hg lasting for 120 msec, whereas a train of 4 pulses within a 320 msec period was able to achieve a maximum tension of 100 mm Hg lasting nearly 400 msec, the latter approximating that of the myocardium. In six other dogs, the rectus muscle pedicle graft was used to replace a segment of the left ventricle (25.5% +/- 2.1% of left ventricular mass) excised under cardiopulmonary bypass. Left ventricular isometric contraction was studied using a left ventricular balloon with stimulators turned on and off. Significant augmentations of left ventricular maximum tension (+19.3% +/- 2.5%, p less than 0.001, paired t test) and left ventricular contractility (+38.3% +/- 9.4%, p less than 0.001) were achieved when the skeletal muscle grafts were stimulated. Thus, in this preliminary study, skeletal muscle graft properly oriented and stimulated is able to augment the left ventricular isometric contractile function after significant loss of left ventricular myocardial mass.

Abdomen↗
PubMed1983

Artificial cardiac stimulation: a current view of physiologic pacemakers.

Artificial pacing of the heart has evolved rapidly over the last 20 years; the physician can now implant "physiologic" pacemakers that preserve the natural order of atrial and ventricular systole. The commonly used pacemakers that pace only the ventricle can induce dizziness, fatigue and syncope and increase congestive heart failure. Physiologic pacemakers can eliminate many of these side effects, but they are more expensive, can be less durable and may induce arrhythmias. Physiologic pacing can provide the greatest benefit and cost-effectiveness when the particular functions of the device are matched to the specific needs of the patient.

Atrial Fibrillation↗
PubMed1983

The effects of splenectomy and splenic implantation on alveolar macrophage function.

The effect of splenectomy on the ability of alveolar macrophages of young and adult rats to phagocytize Pneumococci, Types 3 and 14, and Pseudomonas aeruginosa was studied. Young animals showed a significant (15%) decrease in the phagocytosis of pneumococci type 14, 4 weeks after splenectomy. This depression increased to 30% in 6 weeks' time. Such depression was also noted when young splenectomized rat alveolar macrophages were challenged with Pseudomonas aeruginosa but not with type 3 pneumococci 6 weeks postsplenectomy. Three months following splenectomy in young animals, the rats were grown and they seemed to regain their normal phagocytic activity against pneumococci type 14. Adult rats also showed no alteration in their phagocytic activity against type 3 pneumococci. Autoimplantation of the spleen had a protective effect on the phagocytosis of type 14 pneumococci, and a nonsignificant effect on that of type 3. The present study postulates a modulatory role of the spleen on alveolar macrophage function. Splenectomy may cause the impairment of local lower respiratory immune function, making lungs vulnerable to specific bacterial invasion. Such splenic modulatory effect on alveolar macrophage phagocytic function seems to be age and antigen specific.

Aging↗
PubMed1983

Selective right ventricular dysfunction after coronary artery bypass grafting.

Preoperative and postoperative right (RVEF) and left ventricular ejection fractions (LVEF) were studied by means of radionuclide techniques in 15 patients undergoing coronary bypass operations. Three of them, all with right coronary artery lesions, had postoperative depression of RVEF without concomitant decrease in LVEF. In contrast to those with left ventricular dysfunction, the patients with selective RVEF depression did not have significant elevation of myocardial injury index calculated from creatine kinase isoenzyme (CK-MB) curves.

Cardiac Output↗
PubMed1982

Endorphins in septic shock: hemodynamic and endocrine effects of an opiate receptor antagonist and agonist.

The pathophysiological role of endorphins in septic shock was studied in a porcine model. Septic shock was induced by the intravenous infusion of live Escherichia coli. Naloxone hydrochloride, an opiate receptor blocker, given during profound septic shock, increased blood concentrations of glucagon and cyclic adenosine monophosphate (cAMP), while BP and cardiac output increased transiently. Heart rate and hepatic glycogen value decreased, but insulin and cortisol levels remained unchanged. In contrast, exogenous morphine injection produced further reduction of BP, increased pulmonary wedge pressure, and increased substance P, while growth hormone level and cardiac output remained unchanged. Neither hormonal nor hemodynamic changes were noted in saline controls. Thus, the endogenous opiates appear partly responsible for the hemodynamic derangements during septic shock, and naloxone is able to reverse such depression, even though the effects are transient and relatively minor when naloxone is given late in the course of septic shock. Endogenous opiates also affect the hormonal homeostasis in shock, and there are indications that this may be mediated by the adenylate cyclase-cAMP system.

Animals↗
PubMed1982

Protection of ischemic myocardium: the roles of nutrition and myocardial glycogen.

The ischemic myocardium utilizes glycogen as metabolic substrate. The effects of oral nutrition on the levels of glycogen in the myocardium and of myocardial glycogen content on myocardial tolerance to ischemia were studied. Rats were divided into groups and fed (a) rat chow, (b) rat chow plus 5% dextrose, and elemental diets (c) Flexical (Mead Johnson) or (d) Vital (Ross Laboratories). Another group was starved. All fed groups gained weight normally while the starved rats lost 23% of their body weight. Compared with the effect on rat chow, myocardial glycogen levels were elevated in the Flexical and starvation groups, while Vital depressed the level (P less than 0.01). Thus, both caloric intake and diet affected myocardial glycogen content. Elevation of myocardial glycogen content after starvation contrasted with glycogen disappearance from the liver. The level of myocardial glycogen and left ventricular function after global ischemia were correlated in dogs under cardiopulmonary bypass conditions. During 30 minutes of normothermic aortic cross-clamping, hearts with a preischemic myocardial glycogen content greater than 0.4 g% had less asystole or ventricular fibrillation. Their left ventricular function (stroke work index, myocardial contractility) upon reperfusion was substantially better than those with a myocardial glycogen level of less than 0.4 g%. Dietary manipulation and the nutritional status can thus affect the myocardial glycogen content and may be useful in protecting the myocardium from ischemia.

Animals↗
PubMed1981

Mechanical and cellular bacterial clearance in lung atelectasis.

A pig model with aerosolized pneumococcal bacteria was used to establish that bacterial clearance in a collapsed lung in the perioperative period was decreased compared with the opposite, aerated lung. Cannulation of the right lymphatic duct revealed a significant increase in both lymph flow and ratio of lymph to plasma protein, indicating the development of a high-permeability edema in the collapsed, infected lung. Only 22% of the efferent lymph and blood was positive for the infecting organism. Examination of the T cells obtained by bronchopulmonary lavage showed an initial fall in the numbers of alveolar macrophages at 6 hours after collapse and infection, relative to the opposite, control lung. However, at 24 hours, the collapsed lung had replenished its alveolar macrophage population to such a degree that it was greater than the control. Electron microscopy revealed that the macrophages in the collapsed lung were more activated with increased lysosomal and pseudopodial activity. The in vitro chemotactic function of the macrophages appeared depressed, but phagocytosis and intracellular bactericidal activity were increased in the atelectatic lung. We conclude that there is a decreased bacterial clearance capacity in atelectasis. This finding indicates that impaired mucociliary clearance plays the dominant role in susceptibility to infection.

Animals↗
PubMed1981

Iatrogenic false aneurysms.

Of 270 patients operated upon for aneurysm, 25 patients underwent repair for 28 iatrogenic false aneurysms. Of these, 67.9% were complications of vascular reconstructive surgery and 64.3% occurred at the groin. Iatrogenic false aneurysm was associated with various prosthetic and suture materials and in many the attenuation of host arterial wall appeared to play an important role. Newer invasive procedures, such as arterial infusion of chemotherapeutic agents, also lead to formation of iatrogenic false aneurysm. Infections, present in 50% of the author's series, and intra-abdominal iatrogenic false aneurysm, with abdominal viscera forming part of the aneurysmal wall, posed a technical challenge. Iatrogenic false aneurysm is a potentially grave complication since the mortality and limb loss were each 8% in this series.

Aneurysm↗