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Biomedical subjects

J McIntyre

Publications and source records attributed to J McIntyre.

At least 19 recordsLinked to original sources
PubMed1992

Maternal fever at parturition and its effects on the newborn rabbit.

The febrile response to administration of endotoxin has been reported to be suppressed in both pregnant animals at term and in their newborn. In a previous study we found that newborn rabbits under appropriate conditions to develop a febrile reaction to injected endotoxin. In this investigation we sought to discover whether pregnant rabbits at term had a febrile response to endotoxin, and if so, its effect on thermoregulation in their newborn. Endotoxin (E. Coli LPS) was injected into 19 pregnant rabbits at term. Six delivered spontaneously within an hour. At one hour, 13 were given oxytocin, and a further 8 delivered within five minutes. The colonic temperature (Tc) of the mothers before endotoxin administration and at delivery, and of their young, was measured. The results were compared with those of 10 pregnant rabbits not given endotoxin, and their young. Within 15 min of delivery newborn rabbits from each litter were placed on a thermal gradient to assess their thermoregulatory responses. Pregnant rabbits at term developed an impressive febrile response to injected endotoxin and their young were born with high colonic temperatures. Newborn rabbits from febrile mothers selected higher thermal environments and maintained a higher colonic temperature than the newborn of non-febrile mothers. We conclude that fever is sustained in the first hours of life in the newborn of mothers injected with endotoxin. The possible mechanisms are of considerable interest. None of the pregnant rabbits died after endotoxin administration, but the stillbirth rate was 50% compared with 10% in non-febrile does.

Animals↗
PubMed1991

'Birth to Ten'--pilot studies to test the feasibility of a birth cohort study investigating the effects of urbanisation in South Africa.

'Birth to Ten' is a birth cohort study currently being conducted in the Johannesburg-Soweto area. This paper describes the various pilot studies that were undertaken to investigate the feasibility of a cohort study in an urban area. These studies were designed to determine the monthly birth rate, the timing, frequency and duration of maternal antenatal visits, the timing and frequency of visits to well-baby clinics and the accuracy and reliability of routinely collected growth data. In addition, a birth data collection form was tested to ascertain the appropriateness of its use in clinics within the study area.

Birth Rate↗
PubMed1989

Maternal and fetal sequelae of anticoagulation during pregnancy in patients with mechanical heart valve prostheses.

Previous reports indicate an increased risk of thrombotic and embolic events in patients with mechanical heart valve prostheses during pregnancy. We prospectively followed 50 pregnancies in 49 patients with 62 cardiac prostheses from presentation at the antenatal clinic through the remainder of the pregnancy. Of the 60 mechanical prostheses, 39 were Medtronic-Hall, 7 St. Jude Medical, 7 Starr-Edwards and 7 Björk-Shiley. Forty-three patients were in New York Heart Association functional class I or II and 6 were in functional class III or IV. Forty-five patients were in sinus rhythm and 4 had chronic atrial fibrillation. All patients received warfarin during the first and second trimesters. Forty-one pregnancies proceeded beyond 28 weeks. In 23 of these (group I) warfarin was replaced with heparin at 36 weeks gestation. In the remaining 18 (group II) warfarin was not substituted owing to premature onset of labor. The target prothrombin ratio (international normalized ratio) in patients receiving warfarin was 2.0 to 2.5. The partial thromboplastin time was maintained at 1.5 to 2.5 times the control value in patients receiving heparin. Eleven patients received dipyridamole plus warfarin for the duration of pregnancy. There were no maternal thromboembolic complications or deaths associated with pregnancy. Antepartum hemorrhage occurred in 1 patient at 35 weeks gestation. One patient (group I) experienced peripartum hemorrhage. All patients were hemodynamically stable before delivery, but 2 developed pulmonary edema during labor. The mean fetal birth weight was low (2.54 +/- 0.98 kg). There were 9 abortions (18%), 7 stillbirths (14%), 2 neonatal deaths (4%) and 2 instances of warfarin embryopathy (4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Kinematic strategies and sensorimotor transformations in the wiping movements of frogs.

1. Spinal frogs are known to make coordinated and successful wiping movements to almost all places on the body and legs. Such wiping movements involve a sensorimotor transformation. Information from both the spatial locations of stimuli on the skin and the body configuration of the frog is transformed into a set of motor commands that generate body movements adequate to successfully remove the irritant. The spinal cord itself therefore has a limited capacity for sensorimotor transformations. 2. We examined the kinematics of wiping motions in both spinal and intact leopard frogs and bullfrogs. This data was used to assess the flexibility, precision, and strategy of the kinematic sensorimotor transformations used during wiping. The movements involved the use of redundant degrees of freedom in the limbs. Thus many possible movements or solutions could generate successful wiping. This redundancy allows motor-equivalent movements to be used by the frog. 3. Movements were examined in two dimensions by the use of VHS shuttered-video recording and in three dimensions with the use of a WATSMART system of infrared diodes and cameras. The kinematic analysis was applied to those motions in which the limbs did not interact with kinematic constraints, such as the surface of the substrate or body. These unconstrained motions are directly related to motor commands and thus more easily interpreted. 4. Wiping movements to the back were retained in essentially the same form in both spinal and intact frogs. In both cases wiping had four phases with a fifth occasionally present. The phases included flexion, placing, aiming, and whisking, with occasional extension and multiply repeated wipes. However, the aiming phase was often very brief or absent in this data, and flexion was sometimes omitted in multiple wipes. We found that the placing posture was adjusted in a simple way in response to variations in the location of the target stimulus. The rostrocaudal position of the foot tip was strongly and linearly related to the rostrocaudal stimulus location. 5. During the placing posture, joint angles as well as the limb tip in back wipes had linear relationships to the stimulus' rostrocaudal coordinate. The limb configuration used by the frog allowed a strategy of linear (and potentially independent) postural adjustment of joint angle to stimulus position to generate almost linear endpoint adjustments in the placing phase of wiping. This solution to the ill-posed problem of choosing a joint angle for the placing posture in back-wiping may be computationally simple.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Relationship between plasma atriopeptin concentration and function in the conscious primate.

The renal actions of atriopeptins (APs) 24, 21 and 28 were examined in the conscious primate, macaca fascicularis. AP-24 increased urine flow rate and sodium excretion 20- and 100-fold, respectively. The circulating form of the atriopeptins, AP-28, had similar, even slightly greater (25%) effects when compared to AP-24. AP-21 on the other hand had dramatically reduced effects, less than 20%, when compared to either AP-24 or AP-28. Infusion of AP-24 resulted in marked increases in plasma immunoreactive AP and in renal function. There were direct, significant linear relations between plasma levels and arterial pressure, heart rate, glomerular flow rate, urine flow rate, sodium and potassium excretion. However, the threshold for these effects was generally higher than expected, i.e., greater than 100 pg/ml. Interestingly, there was a 4-fold greater slope for sodium excretion when compared to other renal functions implying a distinctly different mechanism of action. Whereas, the plasma half-life of the peptide was 2 to 3 min, the biological half-life varied from 6 min for sodium excretion to 10 min for urine flow and potassium excretion. The increased slope for the relationship between sodium excretion and plasma AP concentration and the short half-life for sodium excretion indicate that the change in renal sodium handling is independent of urine flow rate and glomerular filtration rate. There is a direct and linear relationship between plasma peptides and renal function which may imply a cause and effect relationship. This extrapolation may, however, be valid only when plasma peptide levels are elevated markedly.

Animals↗
PubMed1987

Enzymology of the pre-priming steps in lambda dv DNA replication in vitro.

We have examined some of the early pre-priming steps of bacteriophage lambda dv DNA replication in vitro. Previous experiments have shown that bacteriophage lambda replication requires host RNA polymerase-dependent RNA synthesis near or at the origin of replication (ori lambda) to initiate DNA synthesis. Using a crude Fraction II enzymatic system we have shown that during RNA polymerase action, at least the bacteriophage lambda O and lambda P replication proteins as well as the host dnaB protein must be present to initiate ori lambda-specific DNA replication. The presence of three other host initiation proteins, dnaG primase, dnaJ, and dnaK, is not required during RNA polymerase action. Because of the apparent absence of a requirement for the dnaJ and dnaK pre-priming proteins during the transcriptional activation step, we propose that the early events of lambda dv DNA replication, prior to action by the dnaG primase, can be divided into two recognizable steps: an early step which requires at least RNA polymerase, lambda O, lambda P, and dnaB, and a subsequent step which requires the action of at least the dnaJ and dnaK proteins.

Bacterial Proteins↗
PubMed1987

Engraftment following T-cell-depleted bone marrow transplantation. II. Stability of mixed chimerism in semiallogeneic recipients after total-body irradiation.

Chronic, stable mixed chimerism of both lymphocytes and erythrocytes was observed in semiallogeneic murine recipients of T-cell-depleted bone marrow transplants that had been conditioned with supralethal total-body irradiation (1100 cGy). Mixed chimerism was extensive, with a wide range of donor engraftment persisting for at least one year after transplant. In both erythrocyte and lymphocyte lineages, decreasing donor engraftment correlated with decreasing marrow dose; however, complete red cell engraftment was more easily achieved than complete lymphocyte engraftment. There were no late graft failures, even among animals exhibiting a substantial host component of hematopoiesis. The extent of mixed hematopoietic chimerism therefore appears to be much greater than had been expected in recipients of T-cell-depleted bone marrow transplants.

Animals↗
PubMed1985

Postconception menses induction using prostaglandin vaginal suppositories.

Vaginal suppositories containing 15 methyl prostaglandin F2 alpha methyl ester in a high-melt base were administered to 60 women desiring early pregnancy interruption who were no more than 56 days' (eight weeks) pregnant as calculated from the first day of the last regular menstrual period (LMP). The purpose of this study was to evaluate the safety, efficacy, and patient acceptability of this mode of noninvasive early abortion. Some factors evaluated during the study included the time interval from insertion of the suppository to the onset of cramping and bleeding. Also measured were immediate and delayed blood loss, nausea, vomiting, and diarrhea. Of the 60 patients entered into the study, 55 procedures have been judged as successful by the prospective criteria set forth in the protocol. There were no deaths or serious complications. Four patients required hospitalization and follow-up dilatation and curettage (D&C). One patient withdrew from the study after receiving a suppository and subsequently delivered a preterm infant.

Abortion, Induced↗
PubMed1979

The Bain circuit.

Explore the source record for details and available documents.

Anesthesiology↗
PubMedDate not supplied

Dynamic internal compliance of a vascular prosthesis.

A new technique was used to measure dynamic internal compliance of a blood vessel or vascular graft subjected to dynamic internal pressure. The internal compliance can be broken into three categories: the volumetric compliance (CV), defined as (dV/V)/dP; the longitudinal compliance (CL), defined as (dL/L)/dP; and radial compliance (CR), defined as (dR/R)/dP. It can be shown mathematically that CV = 2 CR + CL. Thus, measuring any two of the three entities will also give the value for the third. A Dynatek DCT1 dynamic compliance tester was used for measuring the compliance of DenaflexTM biologic grafts and fresh bovine internal thoracic arteries, from which the Denaflex grafts were obtained by fixation. Volumetric compliance was obtained with the test sample mounted in a loose loop that allowed the sample to move both radially and longitudinally. By mounting the sample in a straight fashion that limited longitudinal movement, the radial compliance was determined. The longitudinal compliance was then calculated from the above relationship. Test results show that the fresh bovine artery had an average volumetric compliance of 26.1%/100 mmHg, radial compliance of 9.5%/100 mmHg, and longitudinal compliance of 7.2%/100 mmHg. The Denaflex vascular graft showed a reduction in longitudinal and radial compliance, compared to the fresh raw artery, as a result of extensive fixation.

Animals↗