PubMed Health⌕ Search

Biomedical subjects

P Gerhardt

Publications and source records attributed to P Gerhardt.

At least 19 recordsLinked to original sources
PubMed1992

Positively reinforcing effects of the neurokinin substance P in the basal forebrain: mediation by its C-terminal sequence.

The conditioned corral preference paradigm was used to assess reinforcing effects of substance P (SP) and its N- and C-terminal fragments injected unilaterally into the region of the nucleus basalis magnocellularis (NBM) in rats. Behavioral testing was carried out in a circular open field, consisting of 4 quadrants equally preferred by the animals prior to conditioning. A single conditioning trial was performed. Rats received one microinjection (0.5 microliter) of SP (0.74 pmol), of the N-terminal fragment SP (1-7) and the C-terminal fragment analog DiMe-C7 (each at doses of 0.074, 0.74, and 74 pmol), or vehicle (phosphate-buffered saline; PBS). After injection the rats were placed into the open field with the four quadrants being separated by Plexiglas barriers (closed corral). During the test for conditioned corral preference, when provided a choice between the four quadrants, only those rats injected with SP and the equimolar dose of DiMe-C7 (0.74 pmol) spent more time in the treatment corral, indicative of a positively reinforcing action. None of the other doses of DiMe-C7 and of SP(1-7) influenced the preference behavior. For rats injected with 0.74 pmol SP, SP (1-7), and DiMe-C7, a behavioral analysis was performed for the 15 min conditioning trial. SP and DiMe-C7 reduced rearing and grooming behavior, whereas DiMe-C7 and SP(1-7) increased locomotor activity. However, the acute behavioral effects of SP and its fragments were not correlated with the subsequent place preference behavior during the test trial. The results are discussed in the framework of a structure/activity relationship for the positively reinforcing properties of SP in the region of the NBM. Furthermore, neuropathological implications of the present data are considered, since the homologous nucleus basalis of Meynert in man is known to degenerate in Alzheimer's disease, which is characterized behaviorally by a progressive deterioration in associative functioning.

Animals↗
PubMed1992

Enhanced learning produced by injection of neurokinin substance P into the region of the nucleus basalis magnocellularis: mediation by the N-terminal sequence.

The effect of unilateral injection of the neurokinin substance P (SP) and of certain N- or C-terminal SP-fragments into the region of the nucleus basalis magnocellularis (NBM) on inhibitory avoidance learning was investigated. Rats with chronically implanted cannulae were tested on a one-trial uphill avoidance task. Immediately after the training trial, rats were injected with 0.74 pmol SP or equimolar dosed SP(1-7), DIME-C7, or SP(7-11). Control groups included vehicle-injected rats and a group given an injection of SP(1-7) 5-h after the trial. When tested 24 h later, rats treated with SP or SP(1-7), but not with DIME-C7 or SP(7-11), exhibited longer step-up latencies than vehicle-treated controls. The retention latencies for rats in the SP(1-7) 5-h delay group did not differ from those of vehicle-injected animals, ruling out proactive effects of SP(1-7) on performance. The results show that SP facilitates retention of an inhibitory avoidance response when injected into the NBM. Furthermore, the amino acid sequence that encodes this effect may be located in the N-terminal part of the SP-molecule.

Animals↗
PubMed1992

[Intravascular ultrasound (IVUS): the assessment of tumor infiltration into the vascular wall].

The demonstration or exclusion of tumour infiltration into a vessel wall is made possible by IVUS. This was performed 25 times in 23 patients using a 20 MHz probe where there was suspicion of tumour infiltration on the basis of CT, MRI or angiography. IVUS proved very suitable for clarifying the situation, making direct intravascular evaluation of the affected vessel possible. In 10 cases where surgery was performed, the demonstration or exclusion of tumour infiltration into a vein was confirmed operatively in every case. Further experience is necessary before the value of the method for diagnosing early arterial infiltration can be judged.

Adult↗
PubMed1992

Heat killing of bacterial spores analyzed by differential scanning calorimetry.

Thermograms of the exosporium-lacking dormant spores of Bacillus megaterium ATCC 33729, obtained by differential scanning calorimetry, showed three major irreversible endothermic transitions with peaks at 56, 100, and 114 degrees C and a major irreversible exothermic transition with a peak at 119 degrees C. The 114 degrees C transition was identified with coat proteins, and the 56 degrees C transition was identified with heat inactivation. Thermograms of the germinated spores and vegetative cells were much alike, including an endothermic transition attributable to DNA. The ascending part of the main endothermic 100 degrees C transition in the dormant-spore thermograms corresponded to a first-order reaction and was correlated with spore death; i.e., greater than 99.9% of the spores were killed when the transition peak was reached. The maximum death rate of the dormant spores during calorimetry, calculated from separately measured D and z values, occurred at temperatures above the 73 degrees C onset of thermal denaturation and was equivalent to the maximum inactivation rate calculated for the critical target. Most of the spore killing occurred before the release of most of the dipicolinic acid and other intraprotoplast materials. The exothermic 119 degrees C transition was a consequence of the endothermic 100 degrees C transition and probably represented the aggregation of intraprotoplast spore components. Taken together with prior evidence, the results suggest that a crucial protein is the rate-limiting primary target in the heat killing of dormant bacterial spores.

Bacillus megaterium↗
PubMed1991

Naloxone blocks conditioned place preference induced by substance P and [pGlu6]-SP(6-11).

The effect of prior treatment with the opioid receptor (opioceptor) antagonist naloxone on conditioned place preference produced by the neurotachykinin substance P (SP) and its C-terminal hexapeptide analog [pGlu6]-SP(6-11) (SPC) was investigated in rats. Place conditioning was assessed using a circular open field partitioned into four quadrants that were equally preferred by the rats prior to drug treatment. On three successive days, rats received an intraperitoneal (i.p.) injection of naloxone-HCl (1 mg/kg) or vehicle 15 min before an i.p. injection of either 37 nmol/kg SP, equimolar dosed SPC or corresponding diluent vehicle. After injection the rats were placed into their assigned treatment corral for 15 min. During the test for conditioned corral preference (CCP), when provided a choice between the four quadrants, rats injected with SP or SPC spent more time in the treatment corral compared to vehicle controls, indicative of a positive reinforcing action of these peptides. The pre-treatment with naloxone blocked the positive reinforcing effects of both SP and SPC; when injected alone, naloxone did not influence the preference behavior. Gross locomotor activity was affected by neither treatment. Thus, the positive reinforcing effects of SP and SPC may be mediated via interactions with the endogenous opioid system(s).

Animals↗
PubMed1991

Social policy on the use of aversive interventions: empirical, ethical, and legal considerations.

In an effort to address the controversy regarding the use of aversive interventions in the treatment of individuals with developmental disabilities, this paper presents a review of the literature on the efficacy of such interventions, along with brief reviews of the ethical and legal issues involved. In general, there appears to be empirical, ethical, and legal support for the continued availability of aversive interventions as treatment options, but only if sufficient safeguards are in place.

Autistic Disorder↗
PubMed1990

[Electromagnetic shockwave lithotripsy of gallstones. Preliminary clinical experiences].

75 applications of extracorporeal electromagnetically produced shock-waves were performed on 40 patients with symptomatic gallbladder stones (27 women and 13 men; mean age 43.5 [25-69] years). The patients had up to three stones each, with a maximal diameter of 35 mm. Computed tomography revealed partial calcification of the stones in nine patients. Stone fragmentation succeeded in all patients. Two weeks after lithotripsy two patients were free of stone. Maximal fragment diameter, as measured by ultrasound, was less than 6 mm in 19 patients, 6-10 mm in 14, and 11-15 mm in five. At reexamination of 24 patients three months later, three additional patients were free of stone by ultrasound. No significant side effects were noted during the first 30 days after the procedure. But during further observation mild pancreatitis developed in two, while in one choledochal concrements caused obstructive jaundice which necessitated endoscopic papillotomy. These results demonstrate the effectiveness of this method of fragmenting gall-bladder stones.

Adult↗
PubMed1990

Evidence for dose-dependent positively and negatively reinforcing effects of the substance P C-terminal analog DIME-C7.

Possible positive reinforcing and aversive effects of intraperitoneally (ip) administered substance P (SP) and its C-terminal heptapeptide analog [pGlu5, MePhe8, Sar9]-SP5-11 (DIME-C7) were investigated in rats. The 'conditioned corral preference and avoidance procedure' was used for assessing positive and negative reinforcement. Behavioural testing was conducted in a circular open field consisting of four uniform quadrants equally preferred by the rats prior to drug treatment. On 3 consecutive days, rats received an ip injection of either SP (37 nmol/kg), DIME-C7 (3.7, 7.4, 37, 185 nmol/kg) or vehicle (0.01 M acetic acid in saline) and were placed immediately into their assigned treatment corral. During the test for conditioned corral preference and avoidance, when provided a choice between the four quadrants, rats treated with SP and with the equimolar dose of DIME-C7 (37 nmol/kg) spent significant more time in the drug-paired corral, indicative of positive reinforcing effects. The doses of 3.7 and 7.4 nmol/kg DIME-C7 did not influence the preference behaviour. The high dose of 185 nmol/kg DIME-C7 led to a significant decrease in time spent in the previously drug-paired corral, suggestive of aversive effects of the treatment. Gross locomotor activity was not influenced by either treatment. These results are discussed in the framework of a structure/activity relationship for the reinforcing properties of peripheraly applied SP.

Animals↗
PubMed1990

COBIOTECH's role in biotechnology worldwide.

Curious or sceptical friends often ask, 'What and why is COBIOTECH? What is it doing?'. After serving as President during its formative first years, I attempt here to provide information for the curious and allay concerns of the sceptics about COBIOTECH's emerging role in biotechnology internationally.

Biotechnology↗