Comparative cytogenetics and the determination of primitive karyotypes.
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Animals↗
Biomedical subjects
R J Baker
Publications and source records attributed to R J Baker.
Electrophoretic and immunoelectrophoretic analysis of feline serum proteins.
Serum from 28 clinically healthy cats was subjected to agarose gel electrophoresis and the migration distance relative to albumin was determined. The reference values for the relative and absolute concentrations of each protein fraction were determined and compared to previous reports. The immunoelectrophoretic, crossed immunoelectrophoretic and crossed line immunoelectrophoretic pattern, of a pooled sample of serum from clinically normal cats was determined. The cross-reactivity between goat and/or rabbit monospecific antisera to human proteins and feline serum was determined using immunoelectrophoresis and crossed-line absorption immunoelectrophoresis. Feline alpha-2-macroglobulin, haptoglobin, B1C-globulin, IgG, albumin and ceruloplasmin cross reacted strongly with the monospecific antisera. Alpha-2-macroglobulin migrated anodal to haptoglobin. Lipoproteins and ceruloplasmin were studied using staining procedures described in man. Feline transferrin was precipitated with Rivanol.
Animals↗
Myelolipoma and endocrine dysfunction.
Myelolipoma is an uncommon benign tumor of which the pathogenesis is unknown. It is rarely associated with endocrine disorders. We present a case of a myelolipoma in conjunction with congenital adrenal hyperplasia secondary to 21-hydroxylase deficiency. Nine previously reported cases of myelolipoma associated with endocrine dysfunction are reviewed with potential correlation of the hormonal imbalance to pathogenesis.
Adrenal Gland Neoplasms↗
The acquisition of factual knowledge and the role of the didactic conference in a surgical residency program.
Conferences and seminars are mandated integral components of modern surgical residency programs. We studied the attendance records of house staff at these seminars, as well as an objective measure of cognitive performance (scores achieved in the ABSITE) to determine the role of the teaching seminar in the acquisition of factual knowledge by residents. Seventy five to 85 residents attended weekly scheduled seminars conducted by faculty on a wide range of surgical topics. Attendance records were kept for postgraduate years 1-5 (PGY1-PGY5) and the percentage of residents attending at all conference encounters was calculated. Individual resident ABSITE scores were pooled for each postgraduate year, and expressed as a mean (+/- standard deviation). PGY1 and PGY2 house staff attended conferences poorly (32% and 25% respectively). A marked increase to 56 per cent was noted for the PGY3 level (P less than 0.001), but failed to rise thereafter in the PGY4 and PGY5 years (56% and 52%). ABSITE scores rise with time and progressive seniority, although mean scores remain constant for given postgraduate years. Varying somewhat with the graduating class, PGY5 scores tend to be substantially better than in the PGY1 and PGY2 years. No correlation could be demonstrated between the patterns of conference attendance and the ABSITE scores for each graduating class (r = 0.761; P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Educational Measurement↗
The effect of lipophilic substituents on the biological properties of EDTA complexes containing paramagnetic metal ions.
Complexes of the radioactive paramagnetic metal ions 51Cr(III), 54Mn(II), 59Fe(III), 57Co(II), 64Cu(II) and 153Gd(III) were prepared with EDTA and its derivative containing the lipophilic 1-(4-methylphenyl)-group (MPEDTA), together with the corresponding 99mTc-compounds. The formation of these complexes was verified by electrophoresis and they were screened for potential use as MRI hepatobiliary contrast agents by biodistribution studies in mice. In this series, the MPEDTA complexes of 54Mn(II) and 64Cu(II) showed increased urinary excretion compared to the unsubstituted EDTA complexes, while the MPEDTA complexes of 99mTc, 59Fe, 57Co, 153Gd and particularly 51Cr demonstrated improved hepatobiliary excretion. Further lipophilic substitution should enhance this property but the preparation of such ligands is complicated by cyclisation reactions.
Animals↗
Paramagnetic complexes of manganese(II), iron(III), and gadolinium(III) as contrast agents for magnetic resonance imaging. The influence of stability constants on the biodistribution of radioactive aminopolycarboxylate complexes.
Paramagnetic complexes of manganese(II), iron(III), and gadolinium(III) with many ligands appear to undergo ligand substitution in vivo, producing biodistribution data similar to the hydrated metal ions. To identify ligands likely to be valuable in the preparation of paramagnetic contrast agents, a series of aminopolycarboxylate complexes with stability constants increasing in the order iminodiacetic acid (IDA) less than nitrilotriacetic acid (NTA) less than EDTA less than CDTA less than or equal to DTPA was prepared with 54Mn(II), 59Fe(III), and 153Gd(III) at both tracer and carrier levels. Biodistribution studies in mice suggested that complexes remained unchanged in vivo if their stability constants (K1) were approximately greater than 10(16) for Mn(II) and Gd(III) and greater than 10(22) for Fe(III) complexes at tracer levels. Metal complexes with added carrier appeared to be effectively more stable in vivo, possibly due to dissociation and saturation of metal-binding sites. To avoid the accumulation of metal ions in tissues, new paramagnetic contrast agents containing these metal ions will require stability constants equal to or greater than those identified here.
Animals↗
Tc-99m tertiary butyl isonitrile: a preliminary clinical study of a new myocardial imaging agent in patients with chest pain.
Tc-99m is a preferred agent for nuclear imaging. Tc-99m tertiary butyl isonitrile (Tc-99m-TBI) is the first of a family of lipophilic cations which allow effective imaging of the human myocardium. Twenty-one patients scheduled for coronary angiography for the investigation of their chest pain were studied after injections of this tracer given during exercise, and on a separate visit, at rest. Despite high uptake in the liver and transiently in the lungs, high quality gated images were obtained allowing the assessment of both myocardial uptake and wall motion. The findings corresponded closely with angiographic and ventriculographic assessment of coronary artery disease and myocardial infarction. Redistribution of Tc-99m-TBI was shown to occur in ischemic myocardium analogous to that occurring with thallium-201 (TI-201). Similar agents with more favourable properties may well replace TI-201 as the myocardial imaging agent of choice in the near future.
Angina Pectoris↗
Field articulation testing: a predictor of technical skills in surgical residents.
The relationship between a specialized form of spatial ability known as "field articulation" and technical surgical skill was investigated. This form of spatial ability is operationally defined as the ability to differentiate a simple figure from a complex configurational surround. The relationship between Hidden Figures test scores and average ratings of technical surgical skill made by 17 academic surgical faculty members in two independent institutions was highly significant. Therefore, the use of this test to screen candidates for surgical residency, as well as to assess technical skill potential in junior residents, would appear to be based on valid statistical results.
Clinical Competence↗
A comparison of radiolabelled agents for thrombus imaging using a rabbit model.
The quantitative uptakes of five potential thrombus-localizing radiopharmaceuticals in experimental thrombi of the rabbit jugular vein have been compared to assist with the selection of a thrombus imaging agent for clinical use. Three hours after injection, 111In-platelets were clearly the agent of choice but at 18 h 99mTc-fibrinogen had more favourable characteristics. Both agents were superior to 99mTc-plasmin or its acyl derivatives, including 99mTc-streptokinase-activated anisoylplasminogen. The ease of preparation coupled with favourable biological properties suggest that 99mTc-fibrinogen should be of value in the clinical situation.
Animals↗
The preparation of 99mTc-tertiarybutylisonitrile (99mTc-TBI) by a method suitable for routine clinical use.
The myocardial imaging agent technetium-99m-hexakis (tertiarybutylisonitrile) (99mTc-TBI) was prepared by the reaction of [99mTc]pertechnetate with TBI in 50% ethanol/0.9% saline at 100 degrees C, using stannous chloride as the reducing agent. A study of the reaction parameters enabled the yield to be optimized to better than 90%, although this was reduced to approximately 60% if a purification step was carried out. Chromatographic analysis on ITLC-SG medium showed the final product to be of high radiochemical purity. Biological studies comprising biodistribution in mice over a 2-h period, imaging studies in animals and sub-acute toxicity testing in mice indicated that 99mTc-TBI prepared as here described is a suitable agent for routine clinical use in humans.
Animals↗
Speciation by monobrachial centric fusions.
Fixation of centric fusions in natural populations often encounters minimal meiotic problems due to the ability of trivalents to segregate normally; therefore, little sterility barrier is achieved between a founder population and the parental stock. However, a strong sterility barrier can develop between different founder populations fixed for centric fusions that are monobrachially homologous in the resulting biarmed chromosomes (one arm is homologous but the other is nonhomologous). Hybridization through secondary contact then results in complex multivalents, which encounter problems in segregation and produce unbalanced gametes. Speciation mediated by centric fusions is a peripatric speciation model that does not postulate populational phenomena atypical of those characteristic of most mammals. The model appears applicable to a diversity of mammalian taxa such as bats of the Rhogeessa tumida-parvula complex, shrews of the Sorex araneus complex, and rodents of the Mus musculus and Rattus rattus complexes.
Journal Article↗
The echogenic echinococcal cyst. A diagnostic trap.
Two patients with echogenic solid echinococcal cysts of the liver are reported. The literature of this unusual form of echinococcal liver disease is reviewed.
Biopsy, Needle↗
Acute subdural hematoma: direct admission to a trauma center yields improved results.
We studied 128 patients admitted over a 12 1/2-year period to the Cook County Hospital Trauma Unit with acute subdural hematoma (ASDH): 82 were admitted directly and 46 were admitted after transfer from another hospital; 59% of the entire group died and only 27% obtained a functional recovery. As a group, the transferred patients, who suffered delays of several hours before receiving definitive surgical care, fared significantly worse than the patients with equivalent trauma who were admitted directly. The mortality of the transferred patients was 76%, compared to 50% of the direct admit patients. The outcome was also worse for transfer patients who experienced a 'lucid interval' or with alcohol intoxication. We conclude that the delays associated with failure to admit patients with ASDH directly to a head trauma center cause an excessive mortality and morbidity which could potentially be avoided by proper triage.
Adolescent↗
A review of feline serum protein electrophoresis.
A review of the current literature available on feline serum proteins is presented. Early studies concentrated on comparative aspects of species variations in the electrophoretic pattern. The feline electrophoretogram was divided into five basic regions: albumin, alpha-1, alpha-2, beta and gamma. Different subdivisions of these areas were recognized depending on the support medium used. Current papers have compared the relative migration distances of each globulin peak to the migration of albumin. This "Rf" value enables reliable peak identification. To date, no data exists identifying the individual proteins responsible for the peaks in the alpha and beta regions. The only feline globulin to be studied is haptolobin; however its precise location on the electrophoretic strip was not identified.
Journal Article↗
The current status of recognition and treatment of severe necrotizing pancreatitis.
The diagnosis and treatment of severe necrotizing pancreatitis poses a major controversy in the realm of surgery of the upper gastrointestinal tract. Certainly all investigators are in agreement that the patient with severe necrotizing pancreatitis who responds promptly and effectively to intensive resuscitative efforts and general support measures should not be operated upon. The role of therapeutic percutaneous peritoneal lavage is not well delineated, but probably does not represent any risk to the patient, and should be attempted in patients in whom the response to nonsurgical measures is questionable or transient or in whom sepsis has not supervened. Operation must be undertaken in patients who do not respond to intensive resuscitative efforts, with or without peritoneal lavage, in the first 24 to 36 hours of management, or in whom the initial response is followed by deterioration of vital organ function, specifically pulmonary, renal, and hepatic function. The presence of gallstones associated with pancreatitis that does not respond to therapy promptly also makes early operation mandatory. Although the results in the alcoholic patient are not satisfactory, the results of early operation in nonalcoholic patients with severe necrotizing pancreatitis has been most gratifying, and has yielded far superior survival rates than the nonsurgical approach.
Acute Disease↗
Dysmyelopoiesis in the cat: a hematological disorder resembling refractory anemia with excess blasts in man.
Clinical and pathological findings in three cats affected with a myelodysplastic disorder are presented. This hematological disorder resembles that of refractory anemia with excess of blasts as seen in man. The hematological profile in man is one of peripheral cytopenia in one or all of the marrow cell lines which occurs despite a normal to hypercellular bone marrow. Quantitatively, the marrow has a preponderance of blasts (up to 20%). Qualitative abnormalities consist of dysthrombopoiesis and/or dyserythropoiesis and/or dysgranulopoiesis. Myelodysplastic disorders in the cat are a form of marrow failure often associated with infection with feline leukemia virus. The use of the term refractory anemia with excess of blasts appears to be applicable to the cat and should be considered in evaluating dysplastic disorders of the feline bone marrow.
Anemia, Refractory, with Excess of Blasts↗
Studies of 99mTc-acylplasmins as agents for thrombus detection.
It has been proposed that acylation at the active site of plasmin is able to prevent its reaction with alpha 2-antiplasmin without affecting the fibrin affinity of the enzyme. To investigate the possibility that 99mTc-labelled acylplasmins are improved thrombus-detecting agents, six acylating agents were synthesised and their reaction with plasmin and the labelling of the products with 99mTc studies. Uptake of 99mTc-acylplasmins in an in vitro thrombus model was complicated by precipitation processes, which may in part account for the rapid blood clearance in rabbits and high liver uptake in mice injected with the compounds. Quantitative measurements using an in vivo rabbit thrombus model demonstrated that guanidinobenzoyl-plasmin exhibited nearly a threefold increase in thrombus uptake compared with non-acylated 99mTc-plasmin. The observed uptake is less than that obtained with 125I-fibrinogen at clinically useful time intervals post-injection but represents a significant advantage over the use of 99mTc-plasmin.
Acylation↗
A prospective double-blind comparison of piperacillin, cephalothin and cefoxitin in the prevention of postoperative infections in patients undergoing intra-abdominal operations.
Piperacillin has been shown to be as safe and effective an agent as cephalothin and cefoxitin when used in patients undergoing elective intra-abdominal surgical procedures. Enterococcus species have been shown in other studies to be susceptible to piperacillin, perhaps making it the preferred antibiotic for prophylaxis in clinical settings when enteric flora will be encountered.
Abdomen↗