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Biomedical subjects

C Knapp

Publications and source records attributed to C Knapp.

At least 37 records · Page 2Linked to original sources
PubMed1991

Neuroanatomical localization of kappa 1 and kappa 2 opioid receptors in rat and guinea pig brain.

The neuroanatomical localization of kappa opioid receptors in rat and guinea pig brain was determined by quantitative in vitro receptor autoradiography. Our study shows striking differences in kappa 1 and kappa 2 receptor distributions both between species and within each species. In the rat brain, kappa 1 sites (labeled by [3H]U-69,593) are of low density and confined to a small number of structures. These include the claustrum, endopiriform nucleus, caudate putamen, nucleus accumbens, midline nuclear group of the thalamus, superficial grey layer of the superior colliculus, and central grey. kappa 2 sites (labeled by [3H]ethylketocyclazocine or [3H]bremazocine under conditions in which mu, delta, and kappa 1 binding was suppressed) are more widely distributed throughout all levels of rat brain. kappa 2 sites occur at high density in the caudate putamen, nucleus accumbens, amygdala, thalamus, and interpeduncular nuclei. In guinea pig brain, kappa 1 sites predominate and are of high density in layers I and VI of the neocortex, claustrum, endopiriform nucleus, caudate putamen, nucleus accumbens, and molecular layer of the cerebellum. As in rat brain, kappa 2 sites in guinea pig are more uniformly and widely distributed throughout the brain than are kappa 1 sites. The highest density of kappa 2 sites is in the dorsal parabrachial nucleus, interpeduncular nuclei, mammillary nuclei, and posterior thalamic nuclei. Results from this study demonstrate important interspecies differences in the distribution of kappa 1 and kappa 2 opioid receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesics↗
PubMed1990

Influence of alterations in loading produced by lower body negative pressure on aortic blood flow acceleration.

The objectives of this study were to evaluate the effects of alterations in loading induced by lower body negative pressure on aortic blood flow velocity and acceleration. Twenty-seven normal men were studied during various levels of lower body negative pressure (0 to -60 mm Hg) during which echocardiographic, Doppler and hormonal measurements were obtained. Lower body negative pressure induced a decrease in left ventricular diastolic diameter from 5.18 +/- 0.08 to 4.41 +/- 0.1 cm (p less than 0.0001) and in left ventricular systolic diameter from 3.33 +/- 0.09 to 2.84 +/- 0.1 cm (p less than 0.0001). Shortening fraction remained unchanged. The decrease in diastolic diameter resulted in a reduction in flow velocity integral from 13.8 +/- 0.8 to 7.5 +/- 0.4 cm (p less than 0.0001) and, therefore, in stroke volume from 89.6 +/- 4.7 to 49.5 +/- 2.8 ml (p less than 0.0001). Heart rate reflexly increased from 62.5 +/- 1.9 to 82.2 +/- 2.3 beats/min (p less than 0.0001) as did systemic vascular resistance from 1,280.8 +/- 69.5 to 1,863.4 +/- 121.4 dyne.s.cm-5 (p less than 0.0001). The increase in heart rate was insufficient to maintain cardiac output, which decreased from 5.53 +/- 0.29 to 3.99 +/- 0.21 liters/min (p less than 0.0001). Systolic, diastolic and mean arterial blood pressure was maintained. The negative pressure resulted in a concomitant significant increase in norepinephrine levels from 1.46 +/- 0.09 to 2.056 +/- 0.2 nmol/liter (p = 0.0019) but no change in plasma epinephrine: 0.845 +/- 0.22 to 0.78 +/- 0.11 nmol/liter (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Reduction of left ventricular preload by lower body negative pressure alters Doppler transmitral filling patterns.

The objective of this study was to evaluate the effect of alterations in preload induced by lower body negative pressure on Doppler transmitral filling patterns. Echocardiograms and Doppler recordings were performed in 18 normal young men (aged 23 to 32 years) during various levels of lower body negative pressure (0, -20 and -50 mm Hg). Lower body negative pressure induced a reduction in diastolic velocity integral (from 12.17 +/- 0.79 to 8.42 +/- 0.71 cm, p = 0.0067) and consequently left ventricular diastolic diameter (from 5.11 +/- 0.09 to 4.45 +/- 0.1 cm, p less than 0.0001). There was a significant reflex increase in heart rate from 59.9 +/- 1.9 to 77.1 +/- 2.4 beats/min (p less than 0.0001), but blood pressure was unchanged. This reduction in preload altered Doppler transmittral filling patterns as follows: 1) peak early velocity (E) decreased from 59.2 +/- 3.8 to 39.1 +/- 1.7 cm/s (p less than 0.0001); 2) atrial filing velocity (A) was unchanged (35.58 +/- 1.5 to 33.52 +/- 1.4 cm/s, p = 0.517); 3) E/A ratio decreased from 1.7 +/- 0.13 to 1.19 +/- 0.08 (p = 0.0087); 4) mean acceleration (from 482 +/- 37 to 390 +/- 27 cm/s2, p = 0.03) and mean deceleration (from 327 +/- 31 to 169 +/- 21 cm/s2, p less than 0.001) of the early filling wave were significantly reduced; and 5) peak acceleration (from 907 +/- 42 to 829 +/- 29 cm/s2) and peak deceleration (from 771 +/- 94 to 547 +/- 76 cm/s2) also decreased, but not significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Prognostic factors in patients dying of well-differentiated thyroid cancer.

While some well-differentiated cancers of the thyroid gland are unusually aggressive, most have a more benign clinical behavior, making it difficult to evaluate factors possibly influencing patient survival such as initial surgical treatment. By studying 135 patients who received their initial surgical therapy at our institution, we have defined the prognostically significant factors. Sixteen patients (11.9%) died of disease during a ten- to 20-year follow-up period. Significant factors associated with death from disease were aged 40 years or older, primary lesion size of 2.5 cm or greater, presence of invasive characteristics, and presence of distant metastases. We recommend total thyroidectomy and postoperative sodium iodide I 131 therapy in patients 40 years of age or older, while suggesting a less aggressive approach may be appropriate in the younger patients.

Actuarial Analysis↗
PubMed1988

Role of beta-lactamase and different testing conditions in oxacillin-borderline-susceptible staphylococci.

A group of staphylococcal isolates for which oxacillin MICs were intermediate (1 to 4 micrograms/ml) were studied to establish the role of beta-lactamase in this phenomenon. MICs and MBCs of oxacillin and penicillin with and without clavulanic acid or sulbactam (4 or 16 micrograms/ml, respectively) were determined for 11 Staphylococcus aureus and 2 coagulase-negative Staphylococcus isolates for which oxacillin MICs were 1 to 4 micrograms/ml. The susceptibility studies were done with incubation at 35 and 30 degrees C, and the MICs were read at 24 and 48 h. Of the 13 isolates, 4 became resistant when longer incubation or 30 degrees C incubation was used, and the MICs for 9 remained in the intermediate range. Only three of these strains were susceptible to penicillin, and beta-lactamase was not detected. For 6 of 10 beta-lactamase-positive strains, there was a greater-than-twofold-dilution reduction in oxacillin MICs with the addition of clavulanic acid or sulbactam. Of the four strains that became resistant with incubation at the lower temperature, a clavulanic acid effect was observed in three but only at 35 degrees C. The oxacillin MIC for one of the beta-lactamase-negative strains was also reduced with clavulanic acid; however, this strain was inhibited by 1 microgram of clavulanic acid per ml alone. Bactericidal activity was observed with two or four times the oxacillin MIC in eight strains tested at both temperatures, and the combination with clavulanic acid was bactericidal at higher than four times the MIC in five of the strains at 30 degrees C. Our results suggest that oxacillin intermediate MICs for staphylococcal isolates are due not only to beta-lactamase hyperproduction but also some other unidentified factor. The reduction in oxacillin MIC observed when clavulanic acid was added to one strain was probably due to the intrinsic inhibitory activity of clavulanic acid.

Clavulanic Acids↗
PubMed1988

Gastrointestinal bleeding after craniotomy: a retrospective review of 518 patients.

A retrospective review of the medical records of 518 patients who underwent craniotomy over a 3 year interval was carried out to determine the rate of gastrointestinal bleeding and its relationship to the Glasgow Coma Score. There were 288 [55.5%] males and 230 [44.5%] females in the series; the mean age was 51.5 +/- 18.9 years. Forty percent had brain tumours, 18% had subarachnoid hemorrhage, 14% had spontaneous intracerebral hemorrhage, 19% had head injury and 8% had other diagnoses. Forty-eight [9.3%] of the patients had significant gastrointestinal bleeding, the distribution of which was as follows: hematemesis [37/518], melena [11/518] and/or hematochezia [4/518]. A further 51 [9.8%] had evidence of "coffee ground emesis" only. Of those with a Glasgow Coma Score of less than 10, 21% had significant GI bleeding while only 7% of patients with a Glasgow Coma Score greater than 10 had such a bleed [p less than 0.005]. Further analysis showed that the incidence of GI bleeding in patients who underwent craniotomy increased with decreasing GCS. GI bleeding did not correlate with age, sex, steroid administration or casual use of anti-ulcer medication.

Adult↗
PubMed1981

[Immunopathological complications in enteric yersiniosis: incidence and serological diagnosis (author's transl)].

Using the Widal reaction, significant titres against Yersinia enterocolitica, O-group I and V, were found in 300 of 2843 patients (10.5%) with reactive arthritis or arthralgia, and in 38 (1.3%) against Y. pseudotuberculosis type I to V. Of 510 patients with erythema nodosum 86 (16.9%) and 30 (5.9%), respectively, had significant agglutinin titres against one or the other. The results confirm the aetiological significance of Y. pseudotuberculosis, type I to V, in reactive arthritis and erythema nodosum, as well as the essential saturation of patient sera especially with Salmonella of the B or D group in the demonstration of significant antibody titres against Y. pseudotuberculosis, type II and IV. Complement-fixation tests cannot be recommended for the diagnosis of enteric Yersiniosis and its complications. Only in 201 of 554 serum samples (36.3%) with significant agglutinin titres against Y. enterocolitica O-group I and V (0 : 3 and 0 : 9 after Winblad) did the results of the Widal reaction and the microcomplement-fixation reaction agree, titres apart.

Arthritis↗