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Biomedical subjects

L W Johnson

Publications and source records attributed to L W Johnson.

At least 73 records · Page 4Linked to original sources
PubMed1992

Maintenance energy requirement of llamas.

Five castrated male llamas (mean body weight, 94 kg) were studied in an energy balance trial to determine maintenance energy requirement of llamas. Llamas were fed a 50% oat hay-50% pelleted concentrate diet (2.43 Mcal of metabolizable energy/kg of diet dry matter) at approximately 1.6% of body weight (BW). An 8-day total collection digestion trial was used to determine fecal and urine energy losses. Heat production and methane emissions were determined via indirect respiration calorimetry measurements on each llama fed at the same level of intake as during the digestion trial and subsequently on days 3 and 4 of a period of nonfeeding. Fecal, urine, and methane energy losses of the llamas fed near-maintenance intake were 32.5, 3.5, and 7.1% of gross energy intake, respectively. The postabsorptive metabolic rate, commonly called nonfed (fasting) heat production, was 59.3 kcal/BW0.75. Using a linear relation between postabsorptive and maintenance energy requirement and efficiency of energy use below maintenance of 0.702, metabolizable energy requirement at maintenance was determined to be 84.5 kcal/BW0.75.

Animal Feed↗
PubMed1991

Cardiac catheterization 1990: a report of the Registry of the Society for Cardiac Angiography and Interventions (SCA&I).

This report presents the first year's experience of a totally computerized cardiac catheterization laboratory reporting system, including the results and complications of invasive and interventional procedures. Sixty-three laboratories reported a total of 71,916 patients studied between January 1 through December 31, 1990. Two previous registry reports have been published. Compared with data acquired by previous methods, in spite of an older and sicker population, the mortality for diagnostic procedures has remained remarkably constant (0.11%). The computerized format facilitates data collection and analysis, helps resolve new issues as they arise and serves as a method of monitoring quality of laboratories and individuals.

Adult↗
PubMed1991

The demand for OTC medicines: some Australian evidence.

One of the major social goals of the government in any country is the provision of adequate health care for all its residents. This is certainly the case in Australia where total health expenditure as a proportion of gross domestic product (GDP) has risen since the early 1970s to its current level of over 7%. Well over half of this health expenditure comes from the public purse upon which increasing demands are being made. One potential means of reducing this pressure in the health area is a greater reliance on self health care which includes the use of OTC medicines. The present paper examines the economics of self health care through the specification of an economic model of the demand for self care and the empirical testing of this model using Australian data. The model is then used to calculate the consumer surplus in the market for OTC medicines as a measure of part of the benefits of self medication in the Australian health care system.

Australia↗
PubMed1991

Preventive therapy for malaria.

The incidence of malaria in travelers returning to the United States has been increasing. Persons visiting areas where malaria is endemic should use insect repellent, wear clothing that covers the arms and legs, and remain in screened areas between dusk and dawn. Chemoprophylaxis for travelers consists of weekly doses of chloroquine; a new drug, mefloquine, should be used in the increasing number of countries where chloroquine-resistant malaria is found. Travelers to these areas should carry three tablets of pyrimethamine-sulfadoxine, which should be taken for presumptive treatment of malaria at the onset of chills and fever. It is essential that chemoprophylaxis be continued for four to five weeks after departure from endemic areas. In travelers who develop symptoms of malaria after returning from an endemic area, it is imperative that treatment be started even if blood smears are negative.

Adult↗
PubMed1990

Endometrial biopsy technique and uterine pathologic findings in llamas.

Uterine tissue specimens from 90 llamas with history of infertility were examined and graded microscopically; 83 specimens were obtained by endometrial biopsy and 7 specimens were obtained at necropsy. Fifteen llamas (16.7%) had a normal uterus, which was graded 1A. Twenty-three llamas (25.6%) had minor uterine abnormalities that were graded 1B. Forty-five llamas (50.0%) had appreciable endometritis that was graded 2A. Three llamas (3.3%) had endometritis with gland fibrosis that was graded 2B. Two llamas (2.2%) had notable uterine gland fibrosis that was graded 3A. Two llamas (2.2%) had uterine neoplasia that was graded 3B. Thirty-six llamas had follow-up evaluation; 22 became pregnant, most after some form of treatment. Uterine biopsy in llamas was readily performed without complications and was valuable in identifying a wide range of uterine diseases, most of which were amenable to treatment.

Adenocarcinoma↗
PubMed1990

An Eperythrozoon-like parasite in llamas.

An Eperythrozoon-like RBC parasite was found in a herd of llamas in western Kentucky. The light microscopic and electron microscopic features of the organism were similar to those of E suis. Results of an indirect hemagglutination test for E suis were positive with sera from some parasitemic and nonparasitemic llamas. Parasitemic llamas were usually less than 1 year old and had more severe clinical signs of disease than did older llamas. Poor weight gain and growth, anorexia, and prolonged recumbency were the principal signs of disease. Anemia was usually mild and not accompanied by icterus. Hypoglycemia was associated with parasitemia. Some response to oral or parenteral treatment with tetracycline was noticed, but recrudescence of the infection in some treated llamas was observed. Llamas in nearly every region of the United States have had titers in approximately 12% of samples tested, suggesting that infection with the organism may be widespread. Parasitemic llamas have been recognized in at least 8 states.

Animals↗
PubMed1990

Multiple nonlethal congenital anomalies in a llama.

Whereas numerous congenital anomalies in South American camelids have been reported, multiple anomalies are uncommon. A young llama evaluated for bilateral hind limb lameness was found to have cranially rotated tibial tarsal bones as well as bilateral carpus and tarsus valgus and a ventricular septal defect. These anomalies were likely hereditary, and llamas so affected should not be bred.

Abnormalities, Multiple↗
PubMed1990

Comparison of a DNA probe, complement-fixation and indirect immunofluorescence tests for diagnosing Anaplasma marginale in suspected carrier cattle.

Most estimates of the prevalence of anaplasmosis have been based on serologic data using the complement-fixation (CF) and/or card agglutination tests. Since these tests are considered to be only about 50 percent reliable for detecting carrier cattle in enzootically stable herds, the need for more sensitive diagnostic tests is widely recognized. The objective in the present study was to compare the sensitivity of the CF test with that of the indirect immunofluorescence (IIF) test and a recently developed DNA probe in determining the prevalence of Anaplasma marginale infection in cattle from an enzootic area. The study herd consisted of 52 8-month-old steers and 13 3-year-old cows of mixed beef breed. All cattle were initially tested for this comparative purpose. All but one animal (one that was a positive reactor as assessed by all three tests, and served as a positive control), were treated with long-acting oxytetracycline in an attempt to clear any carrier infections. Each animal was then retested at 1 month and 2 months post-treatment (PT), in an effort to determine if the DNA probe could be used to evaluate the effectiveness of the drug. Six of the 65 (9.2%) initial serum samples were CF positive. In contrast, 60 (92.3%) and 64 (98.5%) of the samples were positive as assessed with the IIF test and the DNA probe, respectively. The DNA hybridization reactions varied in intensity within the sample population indicating different individual levels of infection. The DNA probe hybridized with two samples taken at 1 month PT, and with two different samples taken at 2 months PT. The mean IIF titers were reduced at both the 1 month and 2 month sampling times. These results suggest that the drug did not eliminate infections in all cattle. Some may have been cleared, but, in any event, the drug did reduce the level of infections below the sensitivity of the DNA probe and interrupted continuity of stimulation of antibody. Therefore, the DNA probe and the IIF test appear to be considerably more sensitive in detecting carrier infections than the CF test, and should be considered in future epidemiologic studies.

Anaplasma↗
PubMed1989

Coronary arteriography 1984-1987: a report of the Registry of the Society for Cardiac Angiography and Interventions. I. Results and complications.

This prospective series of results and complications of coronary arteriography from the Registry of the Society for Cardiac Angiography and Interventions is the largest ever reported. Since the initial report published in 1982, the results of coronary artery surgery and angioplasty have improved and therefore older and more symptomatic patients are referred for coronary arteriography. More patients are now studied by the femoral approach, and the major complications of the techniques are similar. Despite studying older and higher-risk patients, the complications are remarkably similar to those reported in the older series. Because of the sicker patients being studied, it is probably unlikely that the complication rate will decrease further in the future. The Society for Cardiac Angiography and Interventions will continue its Registry to follow complication rates of both established and new procedure.

Adult↗
PubMed1989

Coronary arteriography 1984-1987: a report of the Registry of the Society for Cardiac Angiography and Interventions. II. An analysis of 218 deaths related to coronary arteriography.

In a 42-month period, 218 deaths occurred in 222,553 patients undergoing coronary arteriography (0.098%). Age greater than 60 years, NYHA Class IV function, presence of left main coronary disease, and ejection fraction less than 30% all significantly increased the risk of the procedure. Sex and approach (brachial or femoral) used for the catheterization did not affect mortality. Since the SCAI report in 1982, the death rate has dropped significantly in high-risk patients. Low-risk patients (NYHA Class I or normal coronary arteries) who died generally were elderly or had associated valvular heart disease.

Adult↗
PubMed1989

Infectious diseases of New-World camelids (NWC).

Although there are notable infectious conditions that are capable of producing clinical disease in the NWC, overall, these species are quite healthy. Of the bacterial diseases, enterotoxemia caused by Clostridium perfringens types C and D would be deemed the most significant in North America, while type A also would be regarded as important in South America. Other important bacterial infections of potential concern are tuberculosis, Johne's disease, anthrax, malignant edema, actinomycosis, tetanus, and the South American condition referred to as alpaca fever, which, to date, has not been observed in North America. Fungal infections include classical ringworm, principally caused by Trichophyton spp., and the cases of coccidioidomycosis that are associated with the arid desert lands of the southwestern United States. Most notable of naturally occurring viral infections in the NWC would be rabies, ecthyma, and a recently described blindness neuropathy that has been associated with the equine herpesvirus I. NWC can be infected experimentally with agents causing hoof-and-mouth disease and vesicular stomatitis, but naturally occurring cases do not seem to occur. Serological evidence of exposure to many viral agents, including blue tongue, parainfluenza 3, bovine respiratory syncytial virus, bovine herpesvirus I, bovine viral diarrhea, influenza A, and rotavirus, has been demonstrated; however, no clinical disease associated with these agents, as yet, is apparent.

Animals↗
PubMed1989

Llama reproduction.

The reproductive anatomy, physiology, and breeding behavior of the llama is unique enough to make familiarity with it imperative. Female puberty averages 12 months, while many males are not reproductively functional until after 3 years. Proper management of a breeding pair or herd is necessary to maintain maximum reproductive performance. Proof of pregnancy is suggested by rejection of the male and may/should be confirmed by progesterone assay, rectal palpation, or ultrasound techniques. The postpartum female is notable for breeding back rapidly, with high pregnancy rates resulting. Both male and female factors enter into llama infertility, with each gender having significant incidence of reproductive anatomical abnormalities. Management as well as acquired infertility problems (heat factors, trauma, infection, neoplasia, and hormonal imbalances) contribute to the bulk of infertility cases investigated. Techniques used to diagnose infertility in llamas are quite comparable to the equine species; however, female body size and semen analysis in the male present significant challenges. The approach to therapy has been quite empirical to date, owing to lack of consistent problems and numbers to afford conclusive trials. Alterations of pregnancy include resorption, abortions, and stillbirths. Resorption between 30 to 60 days of gestation is reported regularly. Abortions caused by stress occur regularly. Infection abortions caused by leptospirosis, toxoplasmosis, and chlamydiosis are to be expected. Ponderosa pine-related abortions are suspected. In summary, I find use for a broad background in large animal theriogenology to apply to llama infertility. There no doubt are additional diagnostic techniques and therapeutic regimens that have application, and it is up to us all to keep good records and share the information.

Animals↗
PubMed1989

Llama medicine. Nutrition.

The NWC are capable of assimilating a much lower plane of nutrition than we are accustomed to offer conventional domestic herbivores. Their unique gastric anatomy and physiology no doubt contribute to this apparent superiority, which is most evident when compared with sheep under lesser planes of nutrition. Llamas tend to be "cafeteria style" eaters, with some preference being given to taller, coarser forages. Absolute maintenance requirements for caloric, protein, fiber, and mineral content of NWC rations are yet to be finalized using North American feedstuffs, but some guidelines are offered. Proper assessment of body condition, acknowledgment of any nutritional problems, ration analysis, and assessment of management procedures likely will keep NWC nutrition on an even plane here in their new-found environment.

Animal Feed↗
PubMed1989

Infections of the male genitourinary system.

This article provides the primary care physician with the rationale and guidelines for the diagnosis and treatment of common male genitourinary tract infections. Disease entities include urethritis, cystitis, pyelonephritis, epididymitis, and orchitis. The format of pathogenesis, epidemiology, diagnosis, and management will facilitate use by the primary care physician for a specific patient.

Cystitis↗
PubMed1988

Use of temporary pacemakers during coronary angioplasty: an evolving experience with ventricular fibrillation in 400 cases.

Because of a perceived high frequency of ventricular fibrillation when a pacemaker catheter was placed in the right ventricular apex during PTCA, we reviewed our first 400 cases for this complication. The incidence of ventricular fibrillation in the entire group was 10 of 400 cases (2.5%) compared with 17 of 3,806 (0.4%) diagnostic coronary arteriograms performed in our laboratory during the same time period (P less than .001). Ventricular fibrillation occurred more frequently during PTCA when the pacemaker catheter tip was placed in the right ventricular apex (8 of 63 cases, 12.6%) than when it was positioned in either the pulmonary artery, vena cava, or when a pacemaker catheter was not used (2 of 337 cases, 0.6%, P less than .001). Based on these data we have developed a policy of inserting temporary pacemakers prophylactically during PTCA only for patients undergoing dilation of dominant right or dominant left circumflex coronary arteries and in patients with acute myocardial infarction.

Angioplasty, Balloon↗