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Biomedical subjects

R J Baker

Publications and source records attributed to R J Baker.

At least 109 records · Page 6Linked to original sources
PubMed1983

Numerous chromosomal polymorphisms in a natural population of rice rats (Oryzomys, Cricetidae).

Based on G- and C-banded karyotypes of 10 specimens of rice rats, genus Oryzomys (a member of the macconnelli-capito complex but species identification is not possible at this time) from a single isolated population, we found at least nine different centric fusion/fission polymorphisms. No two individuals examined had the same karyotype. Polymorphic variation appears to be stable in the population and not the result of hybridization, human disturbance, or non-specific mutagenic agents. Among the 14 largest chromosomes, polymorphism is restricted to fusion/fission rearrangements. Among the smaller ones, there is polymorphism in the total number of euchromatic arms, which indicates that rearrangements other than fusion/fission exist within our sample. Data from these rice rats document the presence of a greater number of chromosomal polymorphisms within a single, natural population than have previously been reported in a higher vertebrate.

Animals↗
PubMed1983

Allergy in the upper airways.

'Milk makes mucus' many a grandmother has been known to say. On this basis she would not have given milk to a child with a 'head cold'. Little did she know that without any idea of the detailed anatomy of the IgE molecule she was treating milk allergy as it affects the upper respiratory tract.

Allergens↗
PubMed1983

Indigent care limitation in university-owned hospitals.

In recent years the ability of teaching hospitals to finance the expenses associated with the provision of medical care to the indigent has come increasingly into question. Such concerns develop because of the burden cost shifting places on other patients and the potentially adverse market position resulting for the hospital. The University of Nebraska's experience in care for the indigent has been an economic success. The social, political, educational and ethical aspects of policies in this area, however, have not yet permitted definitive assessment.

Costs and Cost Analysis↗
PubMed1983

Comparative accuracy of operative ultrasonography and cholangiography in detecting common duct calculi.

Operative ultrasonography and operative radiographic cholangiography were compared for diagnostic effectiveness with regard to their ability to screen the common bile duct for the presence of calculi. We performed real-time B-mode ultrasonography and cholangiography using two injections of contrast material. In 350 patients, 349 ultrasonic and 285 cholangiographic examinations were performed with technically satisfactory results. The sensitivity, specificity, efficiency, and predictability of a negative test were at a high and comparable level for the two diagnostic procedures. However, the predictability of a positive test for ultrasonography of 91.8% was significantly greater (P less than 0.02) than the predictability of 73.2% for cholangiography. Since predictability of a positive test is based on common duct exploration rather than presumptive evidence of a clinical course, this test may be more valid than the other measures to determine diagnostic effectiveness. The advantages of ultrasonography, which are superior accuracy, favorable image qualities, reduced invasiveness, increased safety, avoidance of contrast material, and lower cost, were contrasted with the problems of ultrasonography, which included a slow learning curve for performance and interpretation of the technique and the limited availability of dedicated ultrasound equipment for surgical operations. We concluded that the advantages outweighed the problems and that operative ultrasonography of the common duct warrants wider application in clinical surgery.

Cholangiography↗
PubMed1983

Effect of Morphine and butorphanol on gallbladder emptying.

In the search for the most appropriate analgesic for patients with biliary tract and pancreatic pain, the authors compared the effect of morphine and the opiate agonist-antagonist butorphanol on gallbladder contraction and emptying stimulated by cholecystokinin octapeptide. Morphine markedly inhibited gallbladder emptying while butorphanol only slightly delayed it. Compared with morphine, the effect of butorphanol was minimal; the latter, therefore, seems to be a suitable analgesic for the treatment of pain of biliary tract or pancreatic origin.

Adult↗
PubMed1982

Emergency transumbilical embolization of bleeding esophageal varices.

Eight patients had major hemorrhage from esophageal varices; in seven, one or two embolizations of the coronary and short gastric veins resulted in cessation of hemorrhage. This procedure can be used in patients with massive ascites, severe coagulopathy, or profound liver failure, as the access route through the dilated umbilical vein can be reached via a supraumbilical incision done with the patient under local anesthesia. All patients died; two deaths were attributable to complications of the procedure, the other six to the severity of the cirrhosis. Sclerotherapy may be combined with coronary vein embolization, but the risk of esophageal perforation may be greater than with sclerotherapy alone.

Adult↗
PubMed1982

Ultrasonic assistance during surgery for pancreatic inflammatory disease.

Real-time B-mode ultrasound scanning was used during 35 operations for inflammatory disease of the pancreas. In 21, ultrasonography was considered helpful in operative management of pancreatic pseudocysts, abscesses, and chronic pancreatitis. Assistance consisted of establishing a diagnosis not made during preoperative testing, more precisely localizing pancreatic abnormalities, and excluding the presence of pseudocyst, abscess cavities, and dilated ducts. Operative ultrasound is a safe and simple technique that may reduce the use of tissue dissection, contrast material injections, and radiation.

Abscess↗
PubMed1981

An assessment of the nature of chromosomal rearrangements in 18 species of Peromyscus (Rodentia: Cricetidae).

G- and C-banded karyotypes from 9 previously unstudied species of Peromyscus are described and compared to the 9 species described in the literature. Additional new data are presented for P. eremicus. A hypothetical evolutionary tree for the 18 species was constructed based on the assumption that, where possible, shared chromosomal rearrangements became established in a common ancestor. A minimum of 60 chromosomal rearrangements (34 heterochromatic additions and 26 pericentric inversions) were needed to construct the most parsimonious tree. Seven of the 18 species have heterochromatin in noncentromeric areas. Three times as many inversions have been identified in the 11 largest pairs as have been observed in the 12 smallest pairs. Peromyscine rodents are characterized by a pattern of chromosomal variation quite distinct from that described for other rodent genera, such as Sigmodon and Mus. Karyotypic orthoselection in rodents appears to be relatively common in closely related species.

Animals↗
PubMed1981

Technetium-99m calcium phytate--optimization of calcium content for liver and spleen scintigraphy: concise communication.

The addition of ionic calcium to technetium-99m stannous phytate produced an agent with improved splenic uptake. In a series of patients, it was found that molar ratios of 2:1 and 3:1 produced scans of optimal diagnostic quality. Studies in mice showed dose-related changes in the biodistribution. Electron microscopy demonstrated that the addition of calcium produced progressive aggregation of the colloid as the molar ratio was increased. Chemical analysis of sodium phytate was essential to obtain accurate ratios.

Animals↗
PubMed1980

Pancreatic abscess after alcoholic pancreatitis.

Primary pancreatic abscess should be suspected in patients with acute or subsiding pancreatitis who have a tender abdominal mass with evidence of local and systemic sepsis. These individuals have a prolonged course of illness compared with patients with uncomplicated pancreatitis. Another group of patients without overt signs of sepsis may have abdominal masses thought to be pseudocysts, with unexplained temperature elevation and leukocytosis. This latter group may also have pancreatic suppuration, termed secondary because of its natural history. The distinction between primary and secondary abscesses is difficult unless time of onset of the preceding pancreatitis is known. Both groups of patients require early, thorough operation. Signs of sepsis or progressive deterioration in patients with acute pancreatitis must be recognized early since untreated abscess is usually fatal. Extensive debridement and external drainage of all abscess cavities present, preferably via posterolateral flank drain sites, are essential to successful surgical treatment of pancreatic abscess.

Abscess↗