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Biomedical subjects

M Andrew

Publications and source records attributed to M Andrew.

At least 235 records · Page 13Linked to original sources
PubMed1984

Hypoxia alters blood coagulation during acute decompression in humans.

Acute decompression is associated with a shortening of the activated partial thromboplastin time (aPTT). This study was performed to examine whether this change in aPTT results from hypoxia or hypobaria. We exposed healthy adults on three separate occasions to 2 h of 1) hypoxic hypobaria (410 Torr, n = 5), 2) hypoxic normobaria (fractional inspired O2 tension = 0.11, n = 4), or 3) normoxic hypobaria (410 Torr breathing supplemental O2, n = 5). The aPTT shortened during hypoxic hypobaria and hypoxic normobaria (P less than 0.05) but was unchanged during normoxic hypobaria. The prothrombin and thrombin times, hematocrit, and concentrations of fibrinogen, total plasma protein, and fibrinogen-fibrin fragment E were unchanged. During hypoxic hypobaria biologic levels of prekallikrein, high-molecular-weight kininogen, and factors XII, XI, X, VII, V, and II were unchanged, but procoagulant VIII (VIII:C) increased 50% without an increase in VIII-related antigen levels (VIIIR:Ag). Fibrin monomer was not detected in any group. In one subject who became ill after 1.5 h of hypoxic normobaria aPTT shortened by 10 s; the platelet count decreased by 93,000/mm3; VIII:C increased fivefold, but VIIIR:Ag only increased three-fold. We conclude that it is the hypoxia which shortens aPTT during acute decompression to 410 Torr and speculate that it results from an increase in plasma VIII:C-like activity.

Adult↗
PubMed1984

Neonatal thrombocytopenia.

In this well-detailed review, the authors review the contribution of platelets to hemostasis, diagnostic approaches to the thrombocytopenic infant, and the classification and treatment of neonatal thrombocytopenia.

Anemia, Aplastic↗
PubMed1984

Fetal blood and tissue PO2 during maternal oxygen breathing.

The effect of 100% oxygen breathing on fetal blood and tissue PO2 was examined in chronically catheterised fetal sheep of 12 pregnant ewes. Blood PO2 was monitored with intravascular polarographic electrodes and tissue PO2 with galvanic electrodes implanted in various tissues. In non-acidotic healthy fetuses, oxygen breathing increased fetal PO2 by 30% within 3 min in arterial blood and within 5 min in tissues. Thereafter blood PO2 increased by a maximum of 40% at 9 min and tissue PO2 rose by a maximum of 52% at 12 min. Blood PO2 returned promptly to control values after 15 min of oxygen breathing but washout of oxygen from tissues was slower and tissue PO2 remained significantly higher in the post-oxygen versus the pre-oxygen period. Continuation of oxygen breathing for 30 min did not lead to any further increase in tissue PO2. Oxygen breathing did not prevent a decrease in fetal PO2 associated with spontaneous myoelectrical activity of the uterus. It is concluded that maternal oxygen breathing leads to a significant increase in both blood and tissue PO2 in the healthy fetus. The majority of the increase occurs within the first 3-4 min and no further increase in either blood or tissue PO2 is observed after 12 min.

Animals↗
PubMed1983

Central venous catheters for out-patient management of malignant disorders.

The use of tunnelled central venous catheters in children with malignant disorders is an effective and safe way of giving out-patient chemotherapy and supportive care. The benefits include ready venous access, ease of administration of chemotherapy, decreased time spent in the out-patient clinic, and less anticipatory vomiting and emotional trauma for patients, parents, and staff.

Adolescent↗
PubMed1983

Assessment of coagulation cascade during air microembolization of the lung.

Experiments were performed to determine whether activation of the coagulation cascade was required for pulmonary vascular permeability to increase during microembolization of the lung. For 30-45 min air microemboli were intravenously infused (0.05-0.10 ml X kg-1 X min-1) into awake sheep with chronic lung-lymph fistulas and anesthetized mongrel dogs. During embolization the pulmonary arterial pressure increased, and O2 partial pressure (PaO2) fell by more than 20 Torr (P less than 0.01). Subsequently lymph flow nearly tripled without a change in the lymph-to-plasma protein concentration ratio. Partial thromboplastin and prothrombin times, biological activity of antithrombin III, and circulating concentration of 125I-labeled dog or sheep fibrinogen did not change during or following air infusion. In two additional sheep an intravenous infusion of thrombin at 0.6 U X kg-1 X min-1 for 15 min resulted in a 20% decrease in 125I-labeled sheep fibrinogen concentration without a change in pulmonary arterial pressure or PaO2. We conclude that air microembolization can increase permeability to water and protein without a detectable activation of the coagulation cascade in the sheep or dog.

Animals↗
PubMed1983

Plasma protease inhibitors in premature infants: influence of gestational age, postnatal age, and health status.

In newborn infants, the influence of gestational age (GA), postnatal age (PA), and health status on the plasma protease inhibitors alpha 2-macroglobulin (alpha 2-M), alpha 1-antitrypsin (alpha 1-AT), C1 esterase inhibitor (C1E-INH), alpha 2-antiplasmin (alpha 2-AP), and antithrombin III (AT-III) was investigated. Inhibitor levels were measured by radial-immunodiffusion and expressed as a percentage of pooled plasma from adults (mean +/- SEM). In total, 54 premature infants (28-36 weeks gestation) were classified at birth as healthy (N = 22) (IV fluids, antibiotics only) or sick (N = 32) (all other support, but excluding infants with disseminated intravascular coagulation (DIC] and studied on Days 1 and/or 7 of life. Healthy term infants (N = 18) and infants with DIC (N = 10) were studied on Day 1 only. All inhibitors except C1E-INH increased with increasing gestational age (P less than 0.01). In healthy premature infants all inhibitor levels reached the normal adult range by 1 week of age. In contrast, at 1 week of age, sick infants had lower levels of alpha 2-M and alpha 2-AP, and higher levels of alpha 1-AT compared to healthy infants (P less than 0.01). The presence of DIC depressed all of the inhibitors on Day 1 except alpha 1-AT when compared to healthy controls (P less than 0.01). Thus, gestational age, postnatal age, and health status all significantly influenced the levels of these plasma protease inhibitors.

Antithrombin III↗
PubMed1983

Demonstration of kallikrein-like protease activity in nonactivated plasma of patients with Cooley's anemia.

Routine evaluation of 12 children with Cooley's anemia revealed that each one had a prolonged partial thromboplastin time. However, prothrombin time and thrombin time were within the normal range. Specific assays demonstrated low levels of the four contact factors: factors XI, XII, prekallikrein, and high molecular weight kininogen. Further investigation revealed activity against para-nitroanilide peptide substrates in unactivated plasma from all 12 patients. Following gel filtration on Sephadex G200, the activity emerged in one peak in the void volume, indicating a molecular weight of greater the 500,000. Activity was greatest against H-D-Pro-Phe-Arg-pNA, the substrate for plasma kallikrein, and was inhibited by diisopropyl fluorophosphate and trasolyl. It was unaffected by hirudin, soy bean trypsin inhibitor, and lima bean trypsin inhibitor. It was destroyed by heating at 56 degrees C. Specific antisera against human prekallikrein and human alpha-macroglobulin did not reduce the activity. It is concluded that a high molecular weight kallikrein-like protease, is present in the plasma of these patients. It is postulated that it is released into the circulation from tissue as a result of damage due to iron overload. It is further postulated that this protease brings about in vivo activation of the contrast factors, resulting in a fall in their circulating levels.

Adolescent↗
PubMed1981

Chelation therapy in beta-thalassemia major. III. The role of splenectomy in achieving iron balance.

Transfusion requirements for 1978 were compiled for 79 patients with thalassemia major (ages 1 to 29 years) who were maintained at hemoglobin concentrations of greater than 10 gm/dl. In 46 patients with intact spleens, the mean transfusion requirement was 258 ml/kg/year, and there was a clear increase with age. The transfusion history prior to 1978 had no influence on the increase of transfusion requirement with age. In contrast, in 33 splenectomized patients, the mean transfusion requirement was 203 ml/kg/year and it did not increase with age. Urinary iron excretion in response to deferoxamine increased with age, with no obvious difference between splenectomized and nonsplenectomized patients. The ability to achieve iron balance with a daily dose of 20 mg/kg of deferoxamine was a function of the transfusion requirement splenectomized patients with lower blood requirements generally achieved negative iron balance, whereas nonsplenectomized patients did not. We conclude that the spleen should be removed when the transfusion requirement exceeds 250 ml/kg/year, which usually occurs between 6 and 8 years of age. In young patients with intact spleens, a higher dose of deferoxamine may be use in order to prevent hemosiderosis.

Adolescent↗
PubMed1978

Lead and morbidity: A dose-response relationship.

Many laboratory tests have been recommended for monitoring factory workers exposed to lead. To select the most useful test the best predictor of selected measures of morbidity was sought. 639 lead-exposed workers in several factories were questioned about abdominal ache, constipation, and fatigue and were examined for hand tremot. Packed-cell volume, blood-lead, urinary lead, and delta-aminolaevulinic acid were estimated in 489 workers. About half of the values for the latter three tests fell into the "excessive" or "dangerous" category of lead absorption. Blood-lead was a better predictor of morbidity than any other laboratory test, and further information did not add appreciably to morbidity prediction. The findings suggest that blood-lead measurement is the most meaningful test for monitoring workers exposed to lead. The effect of lead on morbidity does not appear to depend on its action on the porphyrin metabolic pathway.

Abdomen↗
PubMed1977

Atropine-induced bradycardia in the guinea pig: dose-response.

The effect of atropine sulfate on the heart rate of the unanesthetized guinea pig was studied using a wide range of doses injected via a chronic jugular cannula; dose-response data are presented for the range of 5 mg/kg to 50 mg/kg. A long-lasting dose-dependent bradycardia was produced. This finding is in contrast to the clasically reported effect of atropine in man and dog: tachycardia sometimes preceded by a transient bradycardia. Thus, the guinea pig may be an excellent model for the study of parasympathomimetic, bradycardia-producing effects of atropine.

Animals↗
PubMed1975

A safe and fast-acting surgical anesthetic for use in the guinea pig.

Ketamine [dl-2-(o-chlorophenyl)-2-(methylamino)cyclohexanone] hydrochloride was used in conjunction with Acepromazine [10-3-(dimethylamino)-propyl]phenothiazin-2-yl-methyl ketone] Maleate to produce surgical depth anesthesia in guinea pigs. In tests with 97 animals, an intramuscular injection of 44 mg/kg ketamine hydrochloride plus 2 mg Acepromazine Maleate was found to be effective in producing a surgical level of anesthesia within 2 min after administration. The anesthetic state lasted for an average of 1.5 h and could be safely extended by supplemental administrations of the drugs. This anesthetic combination was found to be fast acting, safe, and easily controlled.

Acepromazine↗
PubMedDate not supplied

Capillary whole blood monitoring of oral anticoagulants in children in outpatient clinics and the home setting.

A whole blood prothrombin time/international normalized ratio (PT/INR) monitor (CoaguChek, Roche Diagnostics Corp., Indianapolis, IN) was assessed in children for its accuracy, reliability, safety, and acceptance by health care personnel and patient's families. The PT/INR values measured by the CoaguChek monitor showed an excellent correlation with PT/INR values measured by the Hospital for Sick Children (HSC) laboratory (r = 0.96) and Hamilton Civic Hospitals Research Centre (HCHRC) laboratory (r = 0.92) in clinic patients and a close correlation with PT/INR values measured by the HSC laboratory (r = 0.76) and HCHRC laboratory (r = 0.74) in patients at home. Reduced correlation in the home setting did not adversely affect clinical management. The whole blood PT/INR monitor is safe and accurate for children requiring oral anticoagulation therapy in either the outpatient clinic or home setting.

Administration, Oral↗