The Wentworth Center for Clinical Engineering: a collaborative and interactive venture.

A program has been developed in Boston to bring together hospital and industrial biomedical engineers, BMETs, CEs, nurses, physicians, the Massachusetts Medical Devices Society, academic engineering technologists, and students. This program is headquartered at the Center for Clinical Engineering at the Wentworth Institute of Technology, and is designed to serve and support the interests of the participants for educational, professional, networking and interdisciplinary activities. Because of the availability of engineering technology programs at Wentworth, and the willingness of local professionals to participate, a comprehensive and unique program has been developed to train BMETs and CEs. This program emphasizes hands-on electronic technology, biomedical lectures and laboratories, management lectures and in-hospital preceptorships under the supervision of BMETs, CEs, biomedical directors and nurses.

Modification of luminol-dependent chemiluminescence reactivity of peripheral blood leukocytes from patients with lymphoreticular tumor, solid cancer, or healthy blood donors by interferon-alpha.

The effect of interferon-alpha (rIFN-alpha 2) on modulating the luminol-dependent chemiluminescence (CL) response evoked by Zymosan or phorbol myristate acetate (PMA) has been studied in heparinized whole blood as well as isolated peripheral blood leukocytes derived from cancer patients and healthy blood donors. The cancer patients, diagnosed with chronic leukemia or lymphoma or solid cancer, were under rIFN-alpha 2 therapy. The CL emission to both Zymosan or PMA was enhanced in the whole blood of the patient's group in comparison to whole blood of healthy blood donors. CL reactivity induced in Dextran-sedimented leukocytes derived from neoplasia patients and healthy blood donors did not differ in the two groups. CL reactivity to Zymosan or PMA could be potentiated when whole blood samples or isolated leukocytes of patients or healthy blood donors were incubated in vitro with rIFN-alpha 2 in the range of 0.001-1000 U/ml prior to addition of CL-stimulating agents. rIFN-alpha 2 itself without adding further agents did not stimulate CL reactivity. Therefore, enhanced CL reactivity to PMA or Zymosan observed in the whole blood of the patients' population appears to be due to the presence of interferon in serum blood components as a consequence of IFN-infusion rather than to other symptoms or treatments of the neoplastic diseases, since the relative CL enhancement in patients is abrogated when isolated blood leukocytes are used for CL assay.

A technique for optimization of enteral feeding regimens: implementation on a microcomputer.

Many clinical factors must be taken into account in choosing an appropriate enteral feeding regimen for a particular patient. In a patient with multiple medical problems, this decision process may become overwhelmingly complex. This paper discusses a mathematical adjunct to aid in this problem. Using patient-specific weights for various clinical factors, an algorithmic determination is made of the degree of correspondence between the characteristics of available preparations and those weights. A microcomputer implementation rendering this method usable to the medical health care professional has been created, and is described.

An analytical approach to creation of parenteral feeding solutions: implementation on a microcomputer.

The creation of a parenteral feeding regimen can be described in mathematical terms by a system of algebraic equations. An example of such a system having clinical applicability is discussed in detail. Since the system is too cumbersome for use by hand or calculator, a microcomputer program incorporating the system was developed, and is also discussed.

An interpretive computer program for analyzing hemodynamic problems in the ICU.

A computer program is described that can generate and interpret hemodynamic profiles, and suggest a therapeutic approach to the identified hemodynamic problem. This program represents the first attempt to develop interpretive software for hemodynamic problems encountered in the ICU.

The use of a pocket computer for hemodynamic profiles.

The pocket computer system for generating hemodynamic profiles is described. This system provides advantages over systems presently used to generate hemodynamic profiles because it is easy to program, simple to use, and is relatively inexpensive.

Apnea monitoring by acoustic detection of airflow.

An acoustic monitor to detect apnea in infants has been developed. Recordings of a signal derived from breath sounds at the nose were made in eight premature infants and compared with observation of the infant and with transthoracic impedance and ECG monitoring. The acoustic monitor detected 26 episodes of apnea lasting 15 seconds or longer which were confirmed by observation and by heart rate slowing of at least 20 beats per minute. Only seven of these episodes were detected by the impedance monitor. The ECG monitor alarmed during the nine spells in which heart rate dropped below 100 beats per minute, 27.5 +/- 9.7 seconds after breath sounds ceased. Inasmuch as the acoustic device detects absent airflow during central or obstructive apnea before bradycardia occurs and is insensitive to body movements, it represents an improved monitoring technique for infants with apnea.

Chemical nature of mouse antibodies homologous to the 3-pyridylazo group: the fine specificities of hybridoma and serum antibodies.

Rabbit antibodies which bind aromatic annular nitrogen-containing haptens exhibit a specificity wherein such nitrogens are distinguished from the closely related aromatic CH group. The mouse hybridoma system was used to extend this work producing hybridoma antibodies homologous to the 3-pyridylazo group. Fine specificity mapping by double antibody radioimmunoassay revealed differences among the individual hybridomas, as well as a greater resemblance of mouse serum antibodies to rabbit serum antibodies than to hybridoma antibodies. Quantitative structure-activity relationships applying the parameters of hapten molar refractivity had hydrophobicity were used to help elucidate the types of intermolecular forces involved in the interaction of pyridine derivatives with the antibodies. The results are consistent with the interpretation that pyridine binding to antibody does not involve desolvation.

Human oviductal fluid proteins.

The popularity of mini-laparotomy provided an opportunity to easily collect human oviductal fluid (HOF). Volumes of HOF produced by two oviducts per 24 hours correlated positively with serum estradiol determinations, while protein concentration in HOF was inversely proportional to estrogen levels. Estrogen appeared to stimulate the production of oviductal fluid in women. The greatest volumes of HOF were observed at midcycle, coincident with the estrogen peak. Protein concentration was lowest at the time of ovulation and highest immediately before and after menstruation. In a large percentage of patients, certain proteins made their appearance at the time of ovulation and receded or disappeared within three to five days thereafter. By electrophoresis, these proteins were seen in the albumin region and in the beta globulin region.

Effect of intrauterine growth retardation on the activities of fetal intestinal enzymes in rats.

The activities of maltase, lactase, alkaline phosphatase and enterokinase were followed in the small intestine of rats during prenatal development. These enzymes were detectable only after the 17th day of gestation. Furthermore, each enzyme exhibited a different pattern of prenatal presence. Maltase activity appeared first (day 18), followed by lactase and alkaline phosphatase (day 19) and then enterokinase (day 20). Except for enterokinase, all of the enzymes attained a level of activity close to the newborn levels at the final day of gestation. Induced intrauterine growth retardation during the 3rd trimester led to a decrease in intestinal weight proportional to the reduction of body weight. These decrease in size of the small intestine was caused by a reduction in cell number rather than cell size. Induced intrauterine growth retardation also resulted in a selective reduction in the specific activities of lactase and alkaline phosphatase, but not of enterokinase and maltase. These results suggest that reduction in maternofetal blood flow in the 3rd trimester of gestation will cause a selective decrease in some brush border enzymes (lactase and alkaline phosphatase) but does not effect others (maltase and enterokinase).

Serum protein binding of salicylate during pregnancy and the puerperium.

A detailed study of salicylate binding to human serum albumin was undertaken because of the widespread use of the drug, its deleterious effect on fetal development (in the laboratory animal) and its well-documented adverse effects on neonatal well-being. Serum was obtained from 82 patients during each trimester of pregnancy, labor, 4 days and 6 weeks post partum. Equilibrium dialysis at 4 degrees C was carried out utilizing therapeutic levels of C-labeled sodium salicylate. Scatchard plots were employed to translate the data into association constants (k') which characterized the binding affinity between salicylate and albumin. At the primary binding site, the mean k' values were: controls (nonpregnant females) 40, first trimester 32, second trimester 28, third trimester 26, labor 15.5, 4 days post partum 18.4, and 6 weeks post partum 37.6 X 10 M. These results demonstrate a decrease in the binding affinity between salicylate and serum albumin as pregnancy proceeds to the puerperium, at which time the binding affinity increases to near control values at 6 weeks post partum. The transplacental concentration of free (unbound) salicylate would be readily available for transplacental transport to exert an effect upon fetal receptors. The changes found may be attributable to competitive or allosteric binding of endogenous compounds such as hormones, characteristic of the normal physiology of pregnancy.

Small intestinal epithelial brush border enzymatic changes in suckling mice infected with reovirus type 3.

Suckling mice infected with reovirus type 3 were examined for changes in the epithelial brush border of the small intestine. After 3 days of infection with reovirus type 3, no significant changes were found in intestinal morphology or activity of any enzymes tested. After 6 days, villi were shortened and blunted with lymphangiectatic lesions and mild mononuclear infiltration in the lamina propria. In addition, there was a significant decrease in lactase (P < 0.001) and enterokinase activity (P < 0.05). However, there were no significant changes in the activities of alkaline phosphatase. In contrast, maltase (P < 0.001) and leucine aminopeptidase (P < 0.05) activities in the infected mice were significantly increased. These data suggest that brush border enzymes are affected differently by reovirus infection.

Reovirus type 3 infection in a suckling mouse: the effects on pancreatic structure and enzyme content.

Alterations in pancreatic function and structure were examined in suckling mice infected intraperitoneally with reovirus type 3. The results were compared to pancreatic zymogen enzyme activities and histology in adult mice infected with the same virus. No effect of the rovirus type 3 on the adult mice could be elicited. In contrast, the suckling mice infected by the reovirus type 3 revealed a definite change in pancreatic zymogen enzymes. However, the zymogen enzymes were affected in a nonparallel fashion and three groups of enzymes with different responses were noted. Amylase and lipase activities were significantly diminished (P less than 0.001) at 6 days of viral infection. The endopeptidases, trypsin (P less than 0.025) and cymotrypsin (P less than 0.001) activities were increased significantly in the infected group. The exopeptidases, carboxypeptidase A and B in the infected animals were not changed significantly compared to the control. It seems reasonable that the reovirus type 3 infection in the suckling mouse causes diminished lipase and amylase activities that might contribute to the pathogenesis of viral enteritis.

The effect of early postnatal acquired malnutrition on intestinal growth, disaccharidases and enterokinase.

The effect of undernutrition on rat small intestine during the critical newborn period was studied. A severe state of protein-energy malnutrition was induced by litter expansion which caused the mean total body weight of experimentally malnourished rats to diminish significantly as compared to control animals. Intestinal weight and total DNA were similarly diminished in the malnourished rats. DNA and protein expressed per gram wet tissue showed no significant differences between groups. Retarded intestinal growth in the malnourished animals was the result of reduced cell number. The mean specific activities of sucrase and maltase were diminished in the experimental group, with mean activities being 20 to 50% of controls, respectively. These differences were larger when expressed as total organ activities. On the other hand, specific lactase activity was significantly higher in undernourished rats but total lactase activity per organ was similar in both groups. Enterokinase specific activity or total organ activity was significantly higher in the undernourished rats.

Interference of intravenous lipid emulsion with the determination of calcium in serum.

A lipid emulsion in concentrations similar to those attained after therapeutic dosages were found to interfere with the determination of total serum calcium measured by a fluorometric method. Calcium results determined by atomic absorption and by fluorometry at different concentrations of lipid emulsion were compared. When lipid concentrations were less than 100 mg/dl, centrifugation was effective in eliminating the artifactural elevation in total serum calcium. Possible reasons for the observed differences are discussed.

Effect of postnatal malnutrition on pancreatic zymogen enzymes in the rat.

In order to characterize the response of the pancreas to undernutrition during the critical neonatal growth phase, acquired postnatal malnutrition was induced in the rat, using the expanded litter. An experimental nursing litter of 16 rats and control litters of 7 to 8 rats were formed. At 19 days of age, the pups were killed. Mean pancreatic wet weight was decreased in the malnourished rat to a greater extent than the decrease in total body weight (49 versus 60%). Decreased organ weight was predominantly the result of a decrease in DNA content and cell number. Enzyme activities expressed per total organ were all diminished; lipase to the greatest extent; trypsin and amylase to an intermediate extent; followed by chymotrypsin and the carboxypeptidases. The specific activities of lipase and trypsin were decreased with lipase, the most severely effected. The low trypsin levels can be attributed to trypsin inhibitor. It is possible therefore, that only the specific activity of lipase is significantly decreased. The decrease in enzyme activities, expressed both as specific activities and as total organ activities were decreased in a nonparallel fashion.

Survival of transplanted normal hepatic cells in bilirubin UDP-glucuronyl transferase deficient Gunn rat liver.

The survival of H3 thymidine labelled normal rat hepatic cells after transplantation into the Gunn rat liver has been investigated. It was found that 0.9% of the cells survived at least 12 weeks after transplantation. This suggests that the observed uridine diphosphoglucuronyl transferase (UDPGT) activity in the genetically deficient Gunn rats after transplantation of normal liver may be partially due to these cells. Time required for the transplantation procedure has a profound effect on the survival of such cells in the recipient liver.