Search PubMed⌕ Search

Biomedical subjects

R R King

Publications and source records attributed to R R King.

At least 19 recordsLinked to original sources
PubMed2001

Partial purification of a novel insect antidiuretic factor from the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), which acts on Malpighian tubules.

In this study, we report for the first time the presence of an antidiuretic factor in the head of the Colorado potato beetle (Leptinotarsa decemlineata (Say)) which acts directly on Malpighian tubules. Biologically active fractions were isolated from the head and separated using molecular weight filtration and high-performance liquid chromatography (HPLC). The resulting fractions were tested for their antidiuretic activity on single isolated Malpighian tubules. Antidiuretic activity was found in the 25% acetonitrile Sep-Pak fraction and the Cn-2 (3000-10,000 MW) and Cn-3 (<3000 MW) fractions, suggesting that the antidiuretic factor was probably a peptide of 25 to 50 amino acids. The antidiuretic factor was very potent, since after five successive fractionations on two different HPLC columns, a high level of inhibition (63%) of fluid secretion by Malpighian tubules could be observed at low dose (0.14 head-equivalent/microl). The antidiuretic factor isolated from the head of the Colorado potato beetle was not affected by repeated freezing and thawing but was sensitive to heat. The differences observed between the Colorado potato beetle antidiuretic factor and other insect diuretic and antidiuretic factors may indicate the possibility of a novel family of water regulation hormones in insects.

Agriculture↗
PubMed2001

Herbicidal properties of the thaxtomin group of phytotoxins.

The thaxtomins are a group of phytotoxins generated by the bacterium Streptomyces scabies (the main causal organism of potato common scab). Available members of the group were assessed for herbicidal activity by a variety of standard tests. Test results indicated that thaxtomin A, the predominant member, was also the most physiologically active. Injury symptoms in most instances were similar to those caused by known cellulose biosynthetic inhibitors such as dichlobenil and isoxaben. Although test results indicated that the thaxtomins had many of the biological properties desirable in a commercial herbicide, they nevertheless lacked the systemic phytotoxicity critical to deliver reliable weed control at low rates.

Bacterial Toxins↗
PubMed2000

Microbial glucosylation of thaxtomin A, a partial detoxification.

Thaxtomin A (1) and B (2), the two major phytotoxins associated with the common scab of potato disease, were transformed into C-14 linked beta-glucosides (3) and (4), respectively, when individually incubated with cultures of Bacillus mycoides in oatmeal broth at 26 degrees C. These biotransformation products when assayed on aseptically produced potato minitubers proved to be much less phytotoxic than the parent compounds.

Bacillus↗
PubMed2000

Use of cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexane platinum (II), a liposomal cisplatin analogue, in cats with oral squamous cell carcinoma.

OBJECTIVE: To determine clinical response and toxic effects of cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexane platinum (II) (L-NDDP) administered i.v. at escalating doses to cats with oral squamous cell carcinoma (SCC). ANIMALS: 18 cats with oral SCC. PROCEDURE: Cats that failed to respond to conventional treatment or had nonresectable tumors were included. Data included a CBC, serum biochemical analyses, urinalysis, cytologic examination of a fine-needle aspirate of enlarged lymph nodes, and thoracic and oral radiographs for clinical staging. A starting dose (75 to 100 mg/m2 of L-NDDP) was administered i.v.. At 21-day intervals, subsequent doses increased by the rate of 5 or 10 mg/m2. Response was evaluated every 21 days by tumor measurement and thoracic radiography. Quality of life was assessed by owners, using a performance status questionnaire. RESULTS: On average, cats received 2 treatments. Toxicoses included an intermittent, acute anaphylactoid-parasympathomimetic reaction, lethargy or sedation (< or = 24 hours), inappetence or signs of depression (< or = 72 hours), mild to moderate increase in hepatic enzyme activity, and melena. Pulmonary, renal, or hematopoietic abnormalities were not evident. Performance status surveys indicated normal behavior and grooming or decreased activity and self-care (19/20 assessments), ate well with or without assistance (15/20), and did not lose weight (15/20). Median survival time was 59.8 days (mean, 54.1 days). CONCLUSIONS AND CLINICAL RELEVANCE: L-NDDP was ineffective for treatment of cats with oral SCC. None of the cats had a complete or partial remission. Acute toxicoses and poor therapeutic response limit therapeutic usefulness of L-NDDP in cats, unless dosage, frequency, and administration procedures can be improved.

Animals↗
PubMed1998

Use of citric acid for neutralizing polymerase chain reaction inhibition by chlorogenic acid in potato extracts.

Polyphenolics are a widely distributed class of plant constituents implicated in the inhibition of the polymerase chain reaction (PCR). Since chlorogenic acid forms the bulk of phenolics in the potato tuber, a range of chlorogenic acid concentrations were tested for inhibition of reverse transcription (RT) and PCR steps. The RT step was inhibited at chlorogenic acid concentrations of 6.0 to 7.5 microg, while the PCR step was inhibited at much lower concentrations of 1.2 to 1.8 microg. Incorporation of 1.2% citric acid at the nucleic acid extraction step prevented darkening of the extract and neutralized the inhibitory effect of chlorogenic acid.

Chlorogenic Acid↗
PubMed1998

Thoracoscopic talc poudrage in malignant pleural effusions: effective pleurodesis despite low pleural pH.

STUDY OBJECTIVE: To determine the effectiveness of pleurodesis by thoracoscopic talc poudrage (TTP) in patients with low pH malignant pleural effusions. DESIGN: Review of prospectively collected data on all thoracoscopic procedures performed from 1982 to 1996. PATIENTS AND SETTING: Twenty-five members in a prepaid, closed-panel health maintenance organization, whose malignant pleural effusion pH was < or = 7.30. INTERVENTIONS: Pleural fluid pH was measured prior to diagnostic and therapeutic, single puncture, rigid thoracoscopy, under local anesthesia, in an operating room. MEASUREMENTS AND RESULTS: Success of pleurodesis was determined with serial radiographs at 10 days, 30 days, and frequent intervals until death or up to 1 year following the procedure. Failure was indicated by evidence of recurrent fluid or persistence of a space between the visceral and parietal pleura. Morbidity of the procedure, days of chest tube drainage, and days of hospitalization were recorded concurrently during hospitalization and outpatient follow-up. Fifty of the 76 patients found to have a pleural pH measurement had a pleural pH >7.30, averaging 7.37 (7.31 to 7.55). The other 26 patients (34%) with pH < or = 7.30 (low pH) are the subjects of this study, of whom 25 were evaluable. Pleurodesis was successful in 22 of 25 (88%), although 4 died prior to 30 days. The three failures all had trapped lung. Chest tube drainage averaged 3.2+/-1.3 days, which approximated the time of hospitalization (3.3+/-1.1 days). There were no thoracoscopy-related deaths; significant morbidity occurred only in one patient with trapped lung, who had prolonged chest tube drainage before and after TTP, and eventually developed empyema. CONCLUSIONS: TTP is an effective pleurodesis technique in malignant pleural effusions, even when the pleural pH is low. The short hospital stay and high success rate make this approach a good choice in palliating symptomatic malignant pleural effusions.

Adult↗
PubMed1994

Induction of serum tumor necrosis factor-alpha and interleukin-6 activity by liposome-encapsulated muramyl tripeptide-phosphatidylethanolamine (L-MTP-PE) in normal cats.

Tumor necrosis factor-alpha (TNF alpha) and interleukin-6 (IL-6) are products of activated monocytes/macrophages with anti-tumor activity. Liposome-encapsulated muramyl tripeptide-phosphatidylethanolamine (L-MTP-PE) is a potent monocyte/macrophage activator. Sera from cats after intravenous L-MTP-PE administration showed TNF alpha activity using a WEHI-164 cell cytotoxicity assay and IL-6 activity using an IL-6 dependent mouse 7TD1 hybridoma cell proliferation assay. Serum TNF alpha activity peaked at 2 hours after L-MTP-PE administration. Significant differences from lipid-equivalent controls were observed at 2 and 3 hours (P < 0.05). Neutralization of serum TNF alpha activity was accomplished with serial dilutions of rhTNF alpha monoclonal antibody. Serum IL-6 activity peaked at 3 hours after L-MTP-PE administration. Significant differences from lipid-equivalent controls were observed at 2, 3, and 4 hours (P < 0.05). Neutralization of serum IL-6 activity was not achieved with goat anti-rhIL-6 polyclonal antibody. Intravenous L-MTP-PE, but not lipid-equivalent, induces serum TNF alpha and IL-6 activity in normal cats.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1991

Cytotoxic tumor necrosis factor activity produced by equine alveolar macrophages: preliminary characterization.

Blood monocytes and alveolar macrophages (AM) were harvested from foals (aged 46 days to 6 months) and cultured in either medium alone or medium containing 10 micrograms/ml bacterial lipopolysaccharide (LPS). After 24 h, culture supernates were collected and analyzed for cytotoxic activity on sensitized L929 cells. Both monocytes and AM that had been treated with LPS produced significantly more cytotoxic activity than the same cell type exposed to medium lacking LPS. LPS-treated macrophages secreted significantly more cytotoxic activity (120 +/- 17.8 U/ml) than did LPS-treated monocytes (47.3 +/- 17.0 U/ml); however, constitutive production of cytotoxin by monocytes was higher (16.7 +/- 4.1 versus 1.2 +/- 1.2 U/ml). The identification of the cytotoxin as tumor necrosis factor (TNF) was strongly suggested by its reactivity with a rabbit antiserum directed against the N-terminal 15 amino acids of human TNF. TNF secretion by AM increased in a dose-dependent manner between LPS concentrations of 0.0001 and 1 microgram/ml, then leveled off. Most of the cytotoxic TNF activity produced by AM was secreted within the first 8 h after initial contact with LPS. Macrophage supernatant TNF was stable over a pH range of 6-11, but lost activity when kept at a pH less than 6. Equine TNF also was destroyed by exposure for 1 h to temperatures more than 60 degrees C. TNF bioactivity was recovered as a single peak after crude macrophage supernate was subjected to analysis by either anion exchange or gel filtration chromatography (molecular weight approximately 56,000).

Animals↗
PubMed1991

Use of pulsed-wave Doppler echocardiography to determine aortic and pulmonary velocity and flow variables in clinically normal dogs.

Transcutaneous pulsed-wave Doppler echocardiography was used to obtain velocity signals from the aortic and pulmonary roots of clinically normal adult dogs tranquilized with acepromazine. Doppler-derived variables included peak ejection velocity, ejection time, and velocity-time integral. The cross-sectional areas of the left and right ventricular outflow tracts were estimated from diameters of the respective orifices measured from two-dimensional echocardiographic images. These data were used to calculate stroke volume and cardiac output for each ventricle. Linear, single variable regressions of ejection time, velocity-time integral, and peak velocity with body weight showed no significant correlations. Significant correlations existed between body weight and estimated left and right ventricular stroke volume and cardiac output. A close correspondence existed between pulmonary and aortic determinations of velocity-time integral, stroke volume, and cardiac output. These results provide an initial framework for interpretation of clinical data by veterinary cardiologists.

Animals↗
PubMed1989

Pulmonic stenosis and right-to-left atrial shunt in three dogs.

Using cardiac catheterization, pulmonic stenosis and right-to-left atrial shunt were diagnosed in 3 young dogs that were evaluated because of weakness, cyanosis, and polycythemia. Injection of contrast material into the caudal vena cava or crossing the atrial septal defect with the catheter tip from the right atrium into the left atrium confirmed the diagnosis. Tetralogy of Fallot, with right-to-left shunt through a ventricular septal defect, is a more common congenital malformation associated with the aforementioned clinical signs. Differentiation between the 2 defects is important, because surgical decompression of the right ventricle will lead to reduction of right atrial pressure and diminishment of the shunt.

Animals↗
PubMed1988

Medical and surgical management of multiple organ infarctions secondary to bacterial endocarditis in a dog.

A 6-year-old male Doberman Pinscher developed multiple organ infarctions secondary to vegetative endocarditis. Clinical signs included fever, nystagmus, head-tilt, inappetence, dehydration, hematuria, and dysuria. The dog was azotemic and anemic and had a high WBC count and high liver enzyme activities. Disseminated intravascular coagulation was diagnosed on the basis of thrombocytopenia and prolonged activated clotting times. Vegetative mitral valvular lesions were evident on M-mode echocardiography. The dog underwent diuresis with physiologic saline solution and was treated parenterally with antibacterial and anticoagulant agents. Surgery was performed to remove an infarcted kidney and an infarcted spleen and to relieve urethral obstruction caused by a large blood clot. Gram-positive cocci were noticed in the biopsy specimens. Mortality associated with organ infarctions secondary to bacterial endocarditis is high, and combined medical and surgical therapy is rarely reported. This dog survived and was alive 38 months after surgery.

Animals↗
PubMed1988

Echocardiographic evaluation of cardiac tamponade in dogs before and after pericardiocentesis: four cases (1984-1986).

The echocardiographic (M-mode and 2-dimensional) features (before and after pericardiocentesis) of 4 dogs with pericardial effusion and clinical evidence of cardiac tamponade were reviewed. M-Mode echocardiography revealed pericardial effusion, with exaggerated swinging motion of the heart and abnormal septal motion in all 4 dogs. In each case, 2-dimensional echocardiography demonstrated right ventricular diastolic free-wall collapse. Three dogs had right atrial diastolic collapse as well. Clinical signs improved, and right ventricular and right atrial diastolic collapse subsided after pericardiocentesis. Two-dimensional echocardiographic features of right atrial and ventricular collapse were used as indicators for determining the presence of cardiac tamponade.

Animals↗
PubMed1984

Exercise performance with added dead space in chronic airflow obstruction.

Individuals with chronic airflow obstruction (CAO) are thought to have limited exercise tolerance primarily because of impaired ventilatory mechanics. We studied the effects of added external dead space (DS) on exercise capacity [maximum O2 consumption (VO2max)], maximum exercise ventilation (VEmax), and blood gases (arterial PO2, PCO2, pH) in 22 patients with CAO [forced expired volume at 1 s (FEV1) = 0.96 +/- 0.41 liter]. Maximum exercise testing (Emax) was performed by incremental cycle ergometry. Patients exercised at base line (BL) and with DS (0.25 liter if FEV1 less than 0.8, and 0.50 liter if FEV1 greater than 0.8 liter), in random-order single-blind fashion. DS resulted in a 12.2% increase in VEmax (P less than 0.001); tidal volume increased (P less than 0.025) while respiratory frequency was unchanged. The VO2max and maximum CO2 production decreased (P less than 0.001) with DS. Arterial PCO2 at rest and at exhaustion increased with DS (P less than 0.001). The pH and arterial PO2 showed small declines at rest and at Emax. Thus, at the lower maximum work load achieved with DS, the patients ventilated more and tolerated a higher arterial PCO2 and a lower arterial PO2 and pH before stopping from dyspnea as compared with the BL exercise run. In contrast, the VO2max of nine normal control subjects was unaffected by the addition of DS. Although VEmax can be increased in CAO patients with DS, this increase is not sufficient to prevent further CO2 retention or a decrease in exercise capacity. We conclude that exercise performance is limited primarily by impaired ventilatory mechanics in CAO.

Aged↗