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Biomedical subjects

S K Johnson

Publications and source records attributed to S K Johnson.

At least 73 records · Page 4Linked to original sources
PubMed1988

Relationships of pelvic structure, body measurements, pelvic area and calving difficulty.

Data on 186 Hereford heifers from five South Dakota ranches were collected to evaluate the relationships of pelvic structure and body measurements with calving difficulty (CD) and pelvic area. Body measurements obtained prebreeding and precalving included two internal pelvic and seven external rump measurements, three pelvic angles and two slope of rump measurements. A calving difficulty score (CDS) of 1 (unassisted) to 8 (Caesarean) was assigned at birth, and calf birth weight was recorded. Data were analyzed using both regression and discriminant analyses. Stepwise regression analysis including all 49 variables showed that calf birth weight was the most important variable influencing CDS (R2 = .33), with precalving pelvic area ranking second (cumulative R2 = .45). Prediction equations that included all variables or only prebreeding variables accounted for 63% and 25% of the variation in CDS, respectively. Pelvic angles and slope of rump variables had low correlations with CDS and pelvic area. Ratios of prebreeding and precalving pelvic areas to calf birth weight significantly decreased as CDS increased. A prebreeding ratio of 4.7 cm2/kg may be beneficial in selection of replacement heifers. In discriminant analyses, the most informative variable in differentiating among levels of CD was calf birth weight. All models significantly discriminated between two CD categories (assisted and unassisted). Models using prebreeding variables only performed as well as those based on precalving variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Abnormal vitamin D metabolism in Paget's disease of bone.

We have studied several biochemical indices of bone turnover and vitamin D metabolism in 32 untreated patients with Paget's disease and in 32 age-matched control subjects. patients with Paget's disease, as expected, were characterized by high bone turnover, as judged by alkaline phosphatase and urinary excretion of hydorxyproline. Serum values of 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) and the ratio of 24,25(OH)2D3 to 25-OHD were significantly lower in patients than in control subjects. Serum concentrations of 1,25(OH)2D3 were normal in Paget's disease. The distribution of values for 24,25(OH)2D3 was log normal. On the basis of the normal range computed from control subjects, patients were divided into those with low or normal values for 24,25(OH)2D3. Disease activity, as judged by biochemical indices was significantly higher in the patients with the lower values of 24,25(OH)2D3. We conclude that Paget's disease is characterized by low circulating concentrations of 24,25(OH)2D3, particularly in patients with more extensive or severe disease.

24,25-Dihydroxyvitamin D 3↗
PubMed1985

Effect of unilateral ovariectomy and injection of bovine follicular fluid on gonadotropin secretion and compensatory ovarian hypertrophy in prepuberal heifers.

A study was conducted to determine whether compensatory ovarian hypertrophy occurred in prepuberal heifers, and if so, could compensatory ovarian hypertrophy be prevented by injecting charcoal-extracted bovine follicular fluid (CFF). An additional objective was to determine the effect of CFF injections on follicle stimulating hormone (FSH) and luteinizing hormone (LH) concentrations following unilateral ovariectomy (ULO). Thirty-one prepuberal Angus, Hereford, and Angus X Hereford heifers were assigned by weight and breed to the following groups: Control-saline injections (C), unilateral ovariectomy-saline injections (ULO) and unilateral ovariectomy-CFF injections (ULO-CFF). In group C, a sham operation was performed on d 0 and both ovaries were removed on d 7. In groups ULO and ULO-CFF, either the right or left ovary was removed on d 0 and the remaining ovary was removed on d 7. From d 0 to 7, each heifer received an injection (iv, 7 ml/injection) of saline or CFF every 12 h. Jugular blood samples were collected immediately before each saline injection from d 0 to 7 and analyzed for FSH and LH. Unilateral ovariectomy increased ovarian (P less than .08) and follicular fluid (P less than .05) weights compared with groups C and ULO-CFF; however, lyophilized ovarian weight was similar (P greater than .05) for all groups. Injections of CFF blocked the increase in ovarian and follicular fluid weight following ULO. The total number of visible follicles per ovary was similar for all groups; however in the ULO group there was an increase (P less than .01) in those 5 to 6 mm and greater than or equal to 9 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Effects of charcoal-extracted, bovine follicular fluid on gonadotropin concentrations, the onset of estrus and luteal function in heifers.

A study was conducted to determine the effect of charcoal-extracted, bovine follicular fluid (CFF) on plasma follicle stimulating hormone (FSH) and luteinizing hormone (LH) concentrations, the interval from luteolysis to estrus, and subsequent luteal function in heifers. Fifteen Angus, Simmental and Hereford heifers were allotted by age, weight and breed to a control (C, n = 8) or a CFF (n = 7) group. Heifers received injections of saline or CFF (iv, 8 ml/injection) every 12 h from d 1 (d 0 estrus) through d 5 of the estrous cycle. On d 6, each heifer was injected (im) with 25 mg of prostaglandin F2 alpha (PGF2 alpha). Blood samples were collected every 12 h by venipuncture starting just before the first saline or CFF injection and continuing until estrus. Thereafter, blood samples were collected every other day during the subsequent estrous cycle and assayed for FSH, LH, estradiol-17 beta and progesterone by radioimmunoassay. Injections of CFF had no effect (P greater than .05) on circulating FSH or LH concentrations from d 1 to 5 relative to the C group; however, there was a transient rise (P less than .05) in FSH concentrations 24 h following cessation of CFF injections. This transient rise in FSH was not immediately followed by an increase in plasma estradiol-17 beta concentrations. Although CFF injections did not interfere with PGF2 alpha-induced luteolysis, the interval from PGF2 alpha injection to estrus was delayed (P less than .05) by 5 d in the CFF group compared with the C group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

How do tranquilizing agents selectively inhibit conditioned avoidance responding?

A number of tranquilizing agents have been shown to inhibit conditioned avoidance responses (CAR) at doses that do not interfere with escape responses (ER). To test the hypothesis that this selective action may be due to differential response strengths of the two responses, rats were trained to press retractable levers in an operant chamber either to avoid a 0.5 mA shock during a 5.0-s warning period or to escape from a low-intensity shock within 5.0 s. The intensity of the latter shock was adjusted for each animal so that CAR and ER were comparable in terms of probability of occurrence and latency. While doses of chlorpromazine, clonidine, diazepam, and morphine that reduced CAR by 30%-50% did not significantly affect high-shock ER, i.e., ER on CAR trials where no CAR occurred, they interfered with low-shock ER to the same degree as CAR. These and other results suggest that the selective blockade of the CAR by these drugs in the CAR paradigm is primarily due to differential strengths of the CAR and ER. They also support studies concluding that tranquilizing drugs reduce avoidance because of a deficit in the ability to initiate motor responses, rather than interfering with associative processes or reducing situation-induced emotional reactions. However, the finding of a small differential effect, at least with chlorpromazine, on CAR and low-shock ER across trials within sessions indicated that different mechanisms may be involved in the suppression of these two responses.

Animals↗
PubMed1981

Stimulation of the adenylate cyclase of A B16 melanoma cell line by pro-opiocortin-related peptides--a structure-activity study.

The ability of alpha-melanotrophin (alpha-MSH or ACTH 1-acetyl-13 amide) and other structurally related peptides derived from the common precursor, pro-opiocortin, to stimulate adenylate cyclase activity in a pigmented B16 mouse melanoma was investigated. The peptides ACTH 1-39, ACTH 1-24, alpha-MSH, ACTH 1-13 amide and beta-MSH all stimulated the enzyme to a similar maximal extent and with similar potency (ED50 = 1.3 . 10(-6) M) except that ACTH 1-39 was slightly less potent (ED50 = 5 . 10(-6) M). ACTH 4-10 (ED50 = 4 . 10(-5) M) and gamma-MSH (ED50 = 5 . 10(-6) M) were partial agonists. ACTH 1-10 was no more effective than ACTH 4-10 in stimulating the enzyme whereas ACTH 1-13 amide was a full agonist. The peptides beta-endorphin and its derivatives, Met-enkephalin and melanotrophin potentiating factor (MPF), failed to stimulate the enzyme. We suggest that the B16 melanoma requires not only the sequence ACTH 4-10 but also some part of the sequence ACTH 11-13, or a similar sequence in the terminal portion of beta-MSH, for full activation of the receptor-linked enzyme.

Adenylyl Cyclases↗
PubMed1978

Sequential nonsurgical and surgical staging of non-Hodgkin's lymphoma.

The results of clinical and surgical staging in a series of 170 patients with non-Hodgkin's lymphoma are reviewed. Advanced disease (Stage IV) was established without laparotomy in 95 patients (56%), primarily through bone marrow biopsy, closed liver biopsy, and peritoneoscopy. Laparotomy revealed a high incidence of liver involvement and involvement of lymph nodes outside of conventional abdominal irradiation portals only in patients with nodular types of pathology and in patients with positive lymphangiograms. The limitations and indications for staging laparotomy are discussed in the context of these findings.

Biopsy↗
PubMed1977

Sequential staging in non-Hodgkin's lymphoma.

The results of staging in 170 patients with non-Hodgkin's lymphoma have been reviewed; all patients were subjected to a series of sequential procedures, including lymphangiography, bone marrow biopsy, and liver biopsy (performed percutaneously, by peritoneoscopy, or by laparotomy). A high incidence of involvement of bone marrow, liver, and abdominal nodes was found in patients with nodular types of lymphoma and in those with diffuse lymphocytic lymphoma, with less than or equal to 20% remaining in stage I or II at the completion of staging in each of these subgroups. Only in patients with histiocytic lymphoma was there an appreciable percentage (31%) remaining in the stage I-II categories after staging. In this study, 75 patients remained in stage III or less after completing the non-surgical phase of staging, and laparotomy was utilized in only 50 patients (30%). At laparotomy, involvement of the liver or the mesenteric or portal lymph nodes was found in 81% of patients with a positive lymphangiogram but in only 18% of those with a negative lymphangiogram.

Biopsy↗
PubMed1976

Split-course radiotherapy of Hodgkin's disease: local tumor control and normal tissue reactions.

One hundred and thirty-six consecutive patients with Stage I-II Hodgkin's disease treated between 1965 and 1969 received a standard tumor dose of 40000 rads to clinically recognized disease using daily fractions of 200 rads given 4 or 5 times per week. Continuous and split-course irradiation, the latter with a 2-2 1/2 week interuption midway through the treatment, were employed in 82 and 54 patients, respectively. "Boost" doses were never given to residual masses at the completion of treatment with either schedule. No loss of therapeutic effectiveness resulted from split-course irradiation, only a single local recurrence having been observed to date. However, patient tolerance with the latter method was substantially better than with continuous irradiation and resulted in fewer subsequent complications. Furthermore, the low incidence of local recurrence fails to support a practice of administering supplementary irradiation to adenopathy which has not completely resolved after a tumor dose of 40000 rads.

Adult↗
PubMed1976

Sequential nonsurgical and surgical staging of non-Hodgkin's lymphoma.

The yield of specific diagnostic procedures in the staging of non-Hodgkin's lymphoma was assessed in 170 consecutive patients who were evaluated with a sequence of diagnostic procedures. Stage III or Stage IV disease was established in 141 of 170 patients (80%) by nonsurgical procedures, including lymphangiography (positive in 78%), bone-marrow biopsy (positive in 39%), percutaneous liver biopsy (positive in 21%), and peritoneoscopy-directed liver biopsy (positive in 29% of those tested). Staging laparotomy showed disease outside conventional nodal irradiation fields in 21 of 26 patients with a positive lymphangiogram, but in only three of 17 patients with a negative lymphangiogram. The yield of staging procedures was highest in patients with nodular lymphomas, only 6% of whom were Stage I or Stage II after staging, but was lowest in patients with histiocytic lymphoma, 30% of whom had localized disease. This study shows that the presence of disseminated disease can be detected in the majority of patients with non-Hodgkin's lymphoma without the use of staging laparotomy.

Adult↗
PubMed1975

Patterns of involvement with malignant lymphoma and implications for treatment decision making.

Decision making in cancer therapy has traditionally evolved through careful observation of the clinical course subsequent to various treatment approaches. This method has also served to delineate the wide spectrum of primary manifestations and patterns of biological behaviour characterizing the malignant lymphomata. Marked disparity has been consistently appreciated between the natural history of lymphomata originating in lymph nodes in contrast to those primary in extranodal sites. The former are usually anatomically generalized at diagnosis whereas primary extranodal lymphomata are commonly localized and more closely resemble carcinomata of the respective organs with their propensity for both regional lymphatic extension and haematogenous spread. Prospective staging of 100 consecutive patients with previously untreated malignant lymphoma has been consistent with this past experience in demonstrating the presence of disseminated involvement in the majority of patients. It has also become apparent that reliance upon either clinical or surgical staging of disease extent is often misleading since widespread disease frequently develops even in those patients staged as having localized involvement and thereby treated with local irradiation. High dose, wide field lymphatic irradiation "á la Hodgkin's disease" seldom constitutes appropriate treatment for patients having lymph node presentations of lymphoma. There is rather a need to recognize the importance of systemic treatment for most cases, negating the utility of routine exhaustive staging since treatment decisions can be based upon readily assessed clinicohistological determinants in the majority of cases.

Adolescent↗