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Biomedical subjects

P Hoff

Publications and source records attributed to P Hoff.

At least 19 recordsLinked to original sources
PubMed1992

Distribution of intraperitoneally injected microspheres labeled with the alpha-emitter astatine (211At) compared with phosphorus (32P) and yttrium (90Y) colloids in mice.

The alpha-emitter 211At was bound to polymer microspheres with a diameter of 1.8 microns. The distributions in mice of intraperitoneally injected 211At microspheres, 90Y silicate colloid, and 32P chromic phosphate colloid were compared. The microspheres with 211At spread rapidly in the peritoneal cavity and remained mainly on the intraperitoneal surfaces. Intraperitoneal injection of 90Y colloid resulted in high levels in intraperitoneal fat and the diaphragm, but 1 day after injection 8.5% of the injected dose per gram was found in blood and after 6 days 2.5% was observed in bone. The highest accumulation of 32P was found in liver and spleen. The injection of additional nonradioactive chromic phosphate colloid resulted in an even higher accumulation of 32P in spleen and liver. The same phenomenon was not observed with 211At microspheres. It is suggested that it is not only the particle size which is important in the distribution of intraperitoneally injected colloid, but the amount of colloid, the type of colloid, the addition or presence of other substances such as ascites, and the animal species might also influence the distribution. In conclusion, the intraperitoneal distribution of 211At-labeled microspheres in mice was favorable compared with 90Y and 32P colloid. These data must be viewed cautiously since the distribution might be different in other animal species or humans.

Animals↗
PubMed1992

[Recent psychiatric classification systems and their significance for forensic psychiatry].

The influence of operationalized diagnostic systems is growing steadily in general and forensic psychiatry. This article discusses the historical context and the advantages and problems that may occur in the application of the new diagnostic systems. It is of special importance that the improvement of communication and reliability within psychiatry does not lead to an uncritical or even dogmatical understanding of the new diagnostic categories.

Diagnosis, Differential↗
PubMed1990

[Psychotic illness during treatment with clomifen].

Psychotic illness recurred in a 25-year-old manic-depressive woman during anti-infertility treatment with clomiphene citrate. The symptoms of this episode (disturbance of consciousness, psychomotoric abnormalities, paranoid-hallucinatory syndrome with transient neurological dysfunctions) differed significantly from previous and subsequent psychotic patterns. No organic cause other than treatment with clomiphene could be discovered despite intensive diagnostic efforts. The pathogenetic role of clomiphene is supported by comparable findings in certain post-partum psychoses. Women with a history of psychiatric disorders are especially at risk.

Acute Disease↗
PubMed1989

Repolarization interactions between cardiac segments of varying action potential duration.

We studied interactions between action potential duration (APD) disperse zones using a double compartment bath in which an APD lengthening solution (Ni++ 2 mmol/L, in Tyrode's solution) was added to one compartment (which contained a portion of the fiber labeled "segment A") followed by addition of an APD shortening solution (6 to 10 mmol/K+) to the other compartment ("segment B"). Standard microelectrode techniques were used in canine Purkinje fibers. With Ni++ in segment A, there was a dispersion in APD measured at both 50% (APD50) and 95% (APD95) of repolarization. After selective addition of K+ to segment B, APD50 dispersion remained constant while APD95 dispersion increased, which indicated a change in the slope of repolarization, a factor with possible arrhythmogenic potential. In addition, a characteristic transitional action potential was seen adjacent to the partition. This had a timely and normally sloping early repolarization followed by a much more gradually sloping shelf. Premature action potentials arising during this shelf had diminished upstrokes. Results of these experiments may be useful in evaluating APD dispersion in relation to arrhythmias.

Action Potentials↗
PubMed1988

Combined MAO-inhibitor and tri- (tetra) cyclic antidepressant treatment in therapy resistant depression.

1. One aspect of using MAO-inhibitors - combining them with tricyclic antidepressants in the treatment of therapy resistant depression - has always been controversely discussed in regard to its unusual toxicity and efficacy. 2. To obtain detailled information about safety and efficacy of such a combined treatment, the charts of 94 inpatients treated with a tranylcypromine - tri- (tetra) cyclic antidepressant combination were reviewed. 3. Within a mean treatment period of 21.9 days, 68% of the patients demonstrated a very good or good improvement to combined treatment, the most effective combination being tranylcypromine + amitriptyline. 4. The incidence of side effects among the patients on the combined regimen was slightly, but not significantly lower as compared to the patients on single tri- (tetra) cyclic antidepressant treatment. 5. Our retrospective study supports the general safety and efficacy of combined MAOI-TCA treatment and suggests that combined treatment, if properly administered, leads to neither serious complications nor an inordinate number of side effects.

Antidepressive Agents↗
PubMed1988

[Kraepelin's basic nosologic postulates. An attempt at a critical evaluation of the later works of Kraepelin].

This study discusses three important papers by Emil Kraepelin, published between 1918 and 1920. Kraepelin supports--in accordance with his teacher Wilhelm Wundt--the view of psychophysical parallelism as a basic principle of dealing with the questions of mental illness. Kraepelin is often called a nosologist; but one must not forget that Kraepelins nosology was not a static one, nor did he vote in favor of any kind of dogmatism. Only when Kraepelin's basic positions are reflected in a differentiated way, his enormous influence on very different parts of psychiatry as science can be understood.

Germany↗
PubMed1986

In vitro characteristics of repolarization abnormality--a possible cause of arrhythmias.

When membrane potential (Vm) remains at depolarized levels for prolonged intervals, quiescence and/or repetitive activations occur. In situ such events would be associated with arrhythmias. One way for such a state to occur is abnormal delay of repolarization leading to marked prolongation of action potential (AP) duration (APD). We studied canine Purkinje fibers in which abnormal AP prolongation had been induced by hypoxic, acidic Tyrode's with or without epinephrine, or by Ni++. AP's exhibited a prolonged secondary plateau with or without early afterdepolarizations (EAD's); they were up to ten minutes in duration. With programmed stimulation, APD's displayed a markedly exaggerated interval dependence with slight increases in diastolic interval causing transitions from normal to abnormal and very long AP's. Normalization of AP's occurred during prolonged rapid pacing trains and only gradually returned to abnormality after cessation of pacing. We also induced EAD's via programmed stimulation at plateau Vm levels. Repolarization could be brought on abruptly via these stimulus-induced EAD's; in certain instances trains of EAD's were required. The above characteristics of the state for which the term "repolarization failure" seems appropriate may have implications for in situ arrhythmias, e.g. in "Torsade de Pointes" ventricular tachycardia.

Animals↗
PubMed1985

Occurrence and transmission of localized repolarization abnormalities in vitro.

Abnormal delay of repolarization leading to prolonged reduction of membrane potential could lead to arrhythmias. Transmission of this type of abnormality from an "abnormal" to a "normal" segment of Purkinje fiber was studied as follows: In a double compartment bath one segment was superfused with unmodified Tyrode's solution and the other with solutions known to induce abnormal prolongation of action potential duration (manifest by prolonged step-like delays in repolarization, or "secondary plateaus" and "early afterdepolarization," that is, activations arising as a consequence of the prolonged depolarized membrane potential). Transmission of abnormalities varied. Complete transmission of secondary plateaus and early afterdepolarizations led to action potentials configurationally similar throughout the fiber. Selective transmission of early afterdepolarization led to the occurrence of new premature action potentials in the normal segment. Cycle length prolongation favored both the occurrence and the transmission of abnormalities. After addition of lidocaine or high potassium ion solutions to the normal segment, shortening of action potential duration occurred and was transmitted from normal to abnormal segment. In this way, reversal of abnormality throughout the fiber occurred via an intervention applied selectively to the normal segment. Observations in this study may be relevant to arrhythmias and their treatment.

Action Potentials↗
PubMed1985

A model for teaching the brief psychosocial interview.

A technique to teach first-year medical students to conduct brief interviews that focus on how medical illness affects the daily life of patients is described. The technique includes a conceptual model of the interview and an explicit teaching method for instructors and students. With the conceptual model, the structure, goals, and techniques of interviewing are identified, and an operational definition of empathic interviewing is provided. The teaching methods include a manual and a seminar for faculty members, a syllabus for students, workshops for students using live patient volunteers, and evaluations of the students' interviews based on the conceptual model.

Education, Medical↗