Biomedical subjects

D T Martin

Publications and source records attributed to D T Martin.

65 records · Page 4Linked to original sources

PubMed1984

Effects of ibuprofen on a porcine model of acute respiratory failure.

Blockade of the arachidonic acid cascade has been shown to improve survival and hemodynamic alterations in animal models of sepsis and acute respiratory failure (ARF). The effects of intravenous ibuprofen, a cyclooxygenase inhibitor, were observed in 20-30 kg pigs with ARF induced by a continuous LD100 infusion of live Pseudomonas aeruginosa (2 X 10(8)/20 kg/min). Cardiopulmonary parameters were monitored in animals intubated, paralyzed, and ventilated at a 250-ml tidal volume and 0.5 FiO2. Pigs were randomly assigned to three groups: Group I received 2 bolus infusions of ibuprofen (12.5 mg/kg) at 20 and 210 min after baseline; Group II had Ps. aeruginosa (2 X 10(8) CFU/20 kg/min) only; Group III received Ps. aeruginosa and 12.5 mg/kg of ibuprofen at 20 and 210 min of ARF. Ibuprofen alone caused no significant changes in cardiorespiratory parameters. With Ps. aeruginosa infusion, significant pulmonary hypertension, hypoxemia, increased intrapulmonary shunt fraction, and systemic hypotension occurred. In the septic animals treated with ibuprofen, oxygenation was improved by a significant decrease in shunt, pulmonary edema, and pulmonary hypertension.

Acute Disease↗

PubMed1984

Portable gamma probe for radioimmune localization of experimental colon tumor xenografts.

Tumor radioimmune detection as presently practiced utilizes a gamma scintillation camera to image tumors. A major clinical limitation is the inability to detect tumors smaller than 2 cm. This limitation is due in part to the inverse square law which states: the number of detected radioactive counts is inversely proportional to the square of the distance separating a radioactive source from the detecting device. A hand-held gamma-detecting probe (GDP) suitable for intraoperative use has been developed. The GDP can be placed near radioactive tumors and take advantage of the inverse square law in a way not possible with external scanning cameras. The use of radiolabeled baboon carcinoembryonic antigen (CEA)-specific antisera produced increased tumor isotope localization in CEA-producing tumors compared to the injection of nonspecific antisera. Tumor isotope-antisera localization was not influenced by tumor volume or time since tumor implantation. The GDP probe counts demonstrated a high degree of correlation with gamma well tissue counts. The probe was able to detect preferential tumor localization in doses lower than could be detected with external scintillation cameras.

Adenocarcinoma↗

PubMed1984

Effect of bilateral adrenalectomy on blood sugar level and plasma refill in a rat hemorrhagic shock model.

Recent studies suggest that the hyperglycemic response to hemorrhage and shock may play a role in promoting plasma refill via its hyperosmolar effect. This relationship was tested in a bilaterally adrenalectomized rat model. After a left carotid arterial cannulation, seven adrenalectomized rats and seven control rats with intact adrenal glands were bled periodically for periods of 15 min followed by 15 min of rest. The initial hemorrhage depleted 7.5% of the total blood volume (TBV) and subsequent hemorrhages 5% each. The study period extended up to 120 min to replicate a hemorrhage of 22.5% of TBV. Micromethod hematocrits (Hct) and blood sugar (BS) were monitored every 15 min and results were analyzed by use of a BMD-P statistical package on an AMDAHL 470 computer. A significant (p less than 0.05) increase in BS during shock was seen in the control rats, while the adrenalectomized animals did not demonstrate a significant hyperglycemic response. There was no significant difference in the plasma refill observed between the two groups. At 60 min, the Hct fell 3.6 +/- 1.7 and 4.6 +/- 0.6 percentage points for control and adrenalectomized animals, respectively, while at 120 min, a respective Hct drop of 7.5 +/- 1.6 and 5.4 +/- 1.1 percentage points was noted. This study indicates that the absence of the hyperglycemic response in the adrenalectomized rats had no effect on plasma refill when compared to the response of control rats with intact adrenals.

Adrenalectomy↗

PubMed1984

Crystalloid versus colloid resuscitation in experimental hemorrhagic pancreatitis.

In a canine model of acute hemorrhagic pancreatitis, crystalloid resuscitation with a balanced salt solution adequately restored plasma volume, supported tissue perfusion and prevented excessive hemodilution without detrimental effects on pulmonary pressures or oxygenation. No advantages in using colloid resuscitation were apparent in our study.

Acute Disease↗

PubMed1983

Correlation of genetic loci and polypeptides specified by bacteriophage T1.

The effects of amber mutations in the 24 known essential genes of phage T1 on phage-directed protein synthesis were examined by SDS-polyacrylamide gel electrophoresis of radiolabelled polypeptides from infected non-permissive cells. Mutations in nine genes (genes 1, 2, 3, 3.5, 5, 7-8, 10, 13.3 and 15) each resulted in the failure to synthesize a single polypeptide. Since the synthesis of each of these polypeptides was at least partially restored in permissive infections and wholly restored in am+ revertant infections we conclude that the affected polypeptide is the primary gene product. Mutations in genes 13.7, 16 and 17, which are required for head formation, are all defective in the synthesis of a 68000 mol. wt. non-structural polypeptide. Mutants in the head genes 13 and 14 fail to cleave P7p to P7, the major structural component of proheads. Gene 14 mutants also fail to make a 45000 mol. wt. non-structural polypeptide which appears to be involved with the gene 13 product in the P7p cleavage reaction. The protein products of the DNA genes 1, 2 and 3.5 are, as expected, synthesized predominantly early in infection whereas those of the remainder, which determine head and tail formation, are made in greater amounts late in infection. Gene 3, a tail gene which has been mapped within the 'early' DNA gene cluster, codes for a 75000 mol. wt. polypeptide synthesized predominantly late in infection. This observation suggests that the early genes 1, 2, 3.5 and 4 do not form an operon under the control of a single early promoter.

Electrophoresis, Polyacrylamide Gel↗

PubMed1976

Polypeptides specified by bacteriophage T1.

The proteins synthesized during the replication of phage TI in u.v.-irradiated Escherichia coli strain B have been examined by polyacrylamide gel electrophoresis of polypeptides pulse-labelled with 14C-amino acids. Up to 50 discrete bands were identified of which about 30 were sufficiently distinct to be classified in terms of time of synthesis. Three polypeptides were synthesized only during the first 6 to 8 min post infection (Class I, Early); 16 or 17 were synthesized predominantly during the later stages of replication starting from 6 to 8 min after infection (Class III, Late); three classes of proteins were made continuously, two at constant rate (Class II, Continuous), five at decreasing rate (Class IV, Early-continuous) and five at increasing rate (Class V, Late-continuous). Of the 14 polypeptides identified as structural components of the virion, three (P7, PI0 and PI) account for about 85% of the particle weight with P7 comprising 50% of the particle. P7 and PI0 appear to result from the cleavage of larger polypeptides. Preliminary studies with amber mutants suggest that normal levels of TI DNA synthesis are not required for the manufacture of late proteins and that a phage-controlled function may control the switch-off of proteins made early and the switch-on of proteins made late.

Coliphages↗

PubMed1971