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Biomedical subjects

P S Freed

Publications and source records attributed to P S Freed.

At least 19 recordsLinked to original sources
PubMed1992

Testicular myxosporidiasis in the flat-backed toad, Bufo maculatus (Amphibia: Bufonidae), from Cameroon, Africa.

Macroscopic cysts measuring less than or equal to 860 x 500 microns were found in the testes of a flat-backed toad, Bufo maculatus, collected in Cameroon, West Africa. On histologic examination, the cysts contained numerous spores of a Myxobolus sp. (Myxozoa: Myxobolidae). Spores in fixed tissues measured 9.2 microns long, 8.9 microns wide, and 4.0 microns thick; the range of values for length, width, and thickness were 8.8 to 9.6 microns, 8.6 to 9.4 microns, 3.6 to 4.4 microns, respectively (n = 20). The shape index (length/width) was 1.03, and ranged from 1.00 to 1.09. Pathology was limited to a slight constriction of adjacent seminiferous tubules by the cysts. No host inflammatory response was noted. This myxozoan is distinct from all other members of the genus infecting anurans and is assigned the name Myxobolus bufonis sp. n.

Animals↗
PubMed1992

Percutaneous intra-aortic balloon counterpulsation.

Intra-aortic balloon pumping is the mainstay in the management of acute left ventricular dysfunction in the critical care setting. Percutaneous insertion affords rapid initiation of the procedure. Complications are in greatest part vascular and infectious. The advent of new-generation, totally automatic, closed-loop IABP systems offers the prospect of increasing the effectiveness of IABP support under most conditions, and especially during arrhythmias. This and other developments suggest that despite its standing as the most widely used temporary cardiac assist device, IABP has still to realize its full therapeutic potential.

Critical Care↗
PubMed1991

Identification of a 15-kilodalton surface glycoprotein on sporozoites of Cryptosporidium parvum.

An immunoglobulin A monoclonal antibody (MAb5C3) was developed against a 15-kDa surface glycoprotein (GP15) of Cryptosporidium parvum sporozoites. Indirect immunofluorescence and colloidal gold immunoelectron microscopy revealed that the antibody reacted with both the sporozoite and merozoite surface plasma membranes. On Western immunoblots, MAb5C3 binding was found to be strongly inhibited when 200 mM N-acetylglucosamine was used as a competing sugar. N-Acetylgalactosamine inhibited binding of the antibody only slightly, whereas glucose, mannose, and galactose failed to inhibit binding. MAb5C3 was found to recognize a similar 15-kDa epitope associated with a Cryptosporidium sp. isolated from guinea pigs. However, MAb5C3 failed to react with any proteins or glycoproteins associated with C. baileyi from chickens, Cryptosporidium sp. (= bovine C. muris) from cattle, C. serpentis from a rat snake, bradyzoites of Besnoitia darlingi from an opossum, sporozoite/oocyst extracts of Caryospora bigenetica from an eastern diamondback rattlesnake, sporozoites of Eimeria nieschulzi and E. papillata from rats and mice, or tachyzoites of Toxoplasma gondii (RH strain). When hybridoma supernatants containing MAb5C3 were administered orally to suckling mice experimentally infected with C. parvum, a 75% reduction in developmental stages was seen histologically at 72 h postinfection and a 67.5% reduction in mean oocyst output was found at 6 days postinfection.

Animals↗
PubMed1991

A new host and locality record for Mesocestoides sp. tetrathyridia (Cestoidea: Cyclophyllidea), with a summary of the genus from snakes of the world.

A new host and distribution record is reported for tetrathyridia of Mesocestoides sp. One of 5 (20%) Namib tiger snakes, Telescopus beetzi, from South Africa was infected. Numerous tetrathyridia were found encapsulated in mesentery attached to the small intestine. Morphological examination of tetrathyridia revealed absence of buds, multiple scoleces, or any other evidence of asexual proliferation. A summary of the snakes of the world reported as hosts of tetrathyridia of Mesocestoides sp. is presented.

Animals↗
PubMed1989

Cryptosporidium spp. in wild and captive reptiles.

Between 1986 and 1988, 528 reptiles originating from three continents were examined for Cryptosporidium spp. Fifteen specimens representing eight genera and 11 species were infected. Statistical evaluation of oocyst structure suggests that multiple species of Cryptosporidium may exist among the reptiles examined.

Animals↗
PubMed1988

Intraaortic balloon pumping for prolonged circulatory support.

Prolonged circulatory support with an intraaortic balloon pump (IABP) is controversial, in part because it has not been performed frequently enough to base treatment policy on adequate data. To help clarify this problem, 733 cases of consecutive patients who were supported by IABP between 1967 and 1982 were analyzed. Twenty-seven patients were supported for 20 days or more (range 20 to 71). Twelve (44%) had prior histories of chronic congestive heart failure. Complications were more frequent in prolonged-support patients than in those assisted for less than 20 days (vascular, 37% vs 15%, p = 0.001; infectious, 67% vs 25%, p = 0.0001; and bleeding, 26% vs 15%, p = 0.04, respectively). The survival rate of prolonged-support patients, however, was 63% (17 of 27), essentially the same as that of the controls (57%, p = 0.5). Of 17 prolonged-pumping patients discharged alive from the hospital, 9 died within 6 months but 8 survived greater than 2 years. Among congestive heart failure patients, none was a long-term survivor. Prolonged IABP support in congestive heart failure patients lacking surgically correctable lesions can extend life while arrangements for definitive therapy are made (transplant, permanent mechanical assistance). Where definitive therapy is unavailable, IABP may provide additional months of life.

Adult↗
PubMed1988

Risks associated with intraaortic balloon pumping in patients with and without diabetes mellitus.

Between 1967 and 1982, intraaortic balloon pumping (IABP) was attempted in 733 patients. Of these, 132 were diabetic: 51 patients were managed with diet alone, 46 patients took oral hypoglycemic agents and 35 patients required insulin. Vascular complications associated with IABP occurred in 34% of the insulin-dependent diabetics, in 18% of other diabetics and in 14% of nondiabetic patients. Infectious complications were 37, 22 and 25%, respectively. Seventy-five diabetic patients (57%) were discharged alive from the hospital after balloon pumping, essentially the same proportion as among nondiabetic patients (58%). It is concluded that although diabetics incur a higher complication rate, IABP is not contraindicated.

Adult↗
PubMed1987

Intraaortic balloon pump insertion: a randomized study comparing percutaneous and surgical techniques.

To compare the percutaneous and surgical techniques of intraaortic balloon pump insertion, 101 patients referred for this procedure were randomly assigned to either percutaneous or surgical insertion. Insertion using the designated technique was successful in 45 (88%) of 51 patients with percutaneous insertion and 48 (96%) of 50 patients with surgical insertion (difference not statistically significant). The time from the beginning of the insertion procedure to the initiation of counterpulsation was 13 +/- 8 minutes for the percutaneous technique versus 31 +/- 16 minutes for the surgical technique (p less than 0.001). In the percutaneous group, 10 patients required Fogarty thrombectomy after balloon pump removal, and 1 patient developed severe leg ischemia requiring immediate termination of balloon pump support. In the surgical group, one patient developed leg ischemia requiring surgical intervention, three patients developed sepsis with bacteremia (including one patient who required vein patch repair of the femoral artery), one patient developed a wound infection requiring debridement and one patient had a cerebral embolus. Aortic dissection, aortoiliac perforation or amputation did not occur in either group. Major vascular complications occurred in 11 patients (22%) with percutaneous insertion versus 2 patients (4%) with surgical insertion (p less than 0.05). It is concluded that although the percutaneous technique for intraaortic balloon pump insertion is faster than the surgical technique and is technically easy, it is associated with a higher incidence of vascular complications.

Blood Pressure↗
PubMed1986

Intraaortic balloon pumping 1967 through 1982: analysis of complications in 733 patients.

Between June 1967 and December 1982, 872 attempts at intraaortic balloon pumping (IABP) were made in 733 patients. Nearly 75% of the patients were men; the proportion of women has increased in recent years. The principal indication for IABP support initially was cardiogenic shock, but over the years, preoperative support, weaning from cardiopulmonary bypass and unstable angina have become the primary indications. Complications of IABP were classified and distributed by severity (minor: I [15%] and II [26%]; major: III [3%] and IV [1%]) and type ([vascular [22%], infectious [22%], and bleeding [7%]). Vascular complication rates were higher in women (32 vs 18%; p = 0.0001), in diabetic patients (32 vs 20%, p = 0.003), and in hypertensive patients (27 vs 20%, p = 0.02). These did not vary with the duration of IABP support (range of duration 0 to 76 days). The rate of infectious complications was related to location where IABP was performed (coronary care unit 26%, operating room 12%). The rate of fever and bacteremia increased significantly with duration of IABP support, but the rate of local wound infection did not. In conclusion, most IABP complications are minor, resolve after balloon removal, are related to vascular status of the patient and, with the exception of bacteremia, are independent of IABP duration.

Adolescent↗
PubMed1984

Prolonged left ventricular dysfunction induced by sequential multifocal ischemic infarcts in dogs.

A method of creating multifocal ischemia in animals leading to left ventricular (LV) functional impairment is described. In a series of 10 mongrel dogs, electrodes were implanted in multiple branches of the coronary arteries. Subsequently, in seven animals, an 800-microA anodal current was applied for 3 h repeatedly over a span of 4-9 weeks. After current application, serum creatine kinase cardiac isoenzyme increased by 12.2 +/- 4.6 U/L (p less than 0.01) and ischemic electrocardiographic changes were consistently present. After an average of 10.7 current applications, all animals were tachypneic on mild exertion. Repeated measurement of LV function demonstrated a substantial reduction in cardiac reserve. No significant changes in three control animals were observed. The animals were sacrificed 80 days (range 49-108 days) after the initial current application. Presacrifice cineangiography and postmortem examination disclosed coronary artery occlusions, stenoses, recanalizations, and collateralization in the distributions expected on the basis of the time elapsed since electrode activation. In all cases, the myocardium exhibited diffuse fibrosis. This method reliably brings about multifocal myocardial ischemic changes in dogs and may provide a chronic LV failure model particularly suitable for the evaluation of LV assist systems.

Animals↗
PubMed1978

Biocompatibility tests of components of an implantable cardiac assist device.

A permanently implantable in-series left ventricular assist device, the dynamic aortic patch (DAP), has been tested in chronic animal experiments. The DAP replaces a section of the intrathoracic aortic wall. Hemothorax and hematocele at the implantation site have been complications in recent experiments. Primary postoperative hemorrhage was ruled out, and the biocompatibility of all components was therefore examined. Dacron velour, Teflon felt, conductive polyurethane, segmented polyether polyurethane, and Teflon-coated polyester fiber sutures were implanted in the pleural cavities of dogs and tested in vitro by culturing canine saphenous vein explants on them. In vivo experiments demonstrated that all components elicited mild to moderate inflammatory reactions, but hematocele occurred only when the components were implanted in the aorta with direct blood contact and exposed to arterial blood pressures. In vitro, cells were cultured on all components with no signs of toxic reactions. These results indicated that the host tolerated all implant components without major inflammatory responses. However, histological data indicated that chronic slow bleeding into or through the Dacron velour in contact with the arterial blood serum could account for hemothorax or hematocele formation. Therefore, a configuration of the assist device using materials impermeable to blood may obviate these difficulties.

Animals↗
PubMed1976

A temporary catheter-tip aortic valve: hemodynamic effects on experimental acute aortic insufficiency.

A catheter-mounted polyurethane cusp was designed to act as a temporary prosthetic aortic valve in the ascending aorta. Acute aortic insufficiency was created in 15 dogs by transventricular tearing of the two aortic valve leaflets with a wire hook. Hemodynamic variables were measured during aortic insufficiency and with the prosthetic valve in place. Comparison of the values showed that the prosthesis functioned as a competent aortic valve. Aortic diastolic pressure increased by 62 +/- 42%, pulse pressure was lowered by 44 +/- 9%, and left ventricular end-diastolic pressure decreased by 45 +/- 18%. Neither cardiac output, coronary blood flow, nor peak systolic pressure was significantly altered. The observed hemodynamic improvement and the simplicity of the design and application suggest that the prosthetic aortic valve may be applicable in the temporary treatment of decompensated aortic insufficiency.

Acute Disease↗
PubMed1975

Demonstration of lack of persistence of effectiveness of intra-aortic balloon pumping of short duration in acute myocardial ischemia.

Experimental studies were carried out to quantitate the effectiveness of intra-aortic balloon pumping (ABP) in reducing severity and extent of myocardial ischemia and the persistence of induced changes after cessation of pumping. Ligation of the anterior descending coronary artery was followed by one hr of observation, IABP for one hr (12 dogs) or 3 hrs (12 dogs) and an additional one hr of observation. Epicardial mapping utilizing 20 electrodes was used to obtain the ST segment elevations (Sigma ST) and numbers of electrodes showing ischemic ST CHANGES (NST) in each group. Reductions of SigmaST of approximately 15% and 33% and reduction of NST of 15% and 20% was observed in the one and 3 hr groups respectively, and persisted throughout the period of pumping. Both parameters were noted to increase within 5 mins after cessation of IABP in both groups. SigmaST frequently rose to almost pre-IABP values in the group pumped for one hr. The group pumped for 3 hrs showed SigmaST increase of approximately 15% and NST increase of approximately 16%. Hemodynamic measurements showed in both groups a mean systolic unloading of approximately 10% and 10-20% mean diastolic augmentation. In conclusion, IABP of short duration (1-3 hrs) early after the onset of acute ischemis (one hr) induces a significant but transient decrease in SigmaST and NST, which reflects a reduction in myocardial ischemia. Further study is required to evaluate the effectiveness of intra-aortic balloon pumping, if intitated several hours after the onset of ischemia, to reproduce the clinical reality of a patient with an acute myocardial infarction.

Animals↗