Should radiofrequency therapy be performed in every symptomatic patient with supraventricular tachycardia? (Pro drug position)

The indication for treatment of paroxysmal supraventricular tachycardia depends on the frequency and severity of the tachycardia attacks. If the tachycardia attacks are mildly symptomatic and occur only once or twice a year, there is no indication for either continuous drug therapy or radiofrequency ablation. The only therapeutic measure required is termination of each acute event. If symptoms occur frequently, long-term antiarrhythmic drug therapy is then indicated and will be effective for chronic prophylaxis in most individuals with a low risk of proarrhythmic events. Only in patients with severe or life-threatening symptoms or cases refractory to drug therapy would radiofrequency ablation possibly be justified.

Segmentation of microcalcifications in mammograms

A systematic method for the detection and segmentation of microcalcifications in mammograms is presented. It is important to preserve size and shape of the individual calcifications as exactly as possible. A reliable diagnosis requires both rates of false positives as well as false negatives to be extremely low. The proposed approach uses a two-stage algorithm for spot detection and shape extraction. The first stage applies a weighted difference of Gaussians filter for the noise-invariant and size-specific detection of spots. A morphological filter reproduces the shape of the spots. The results of both filters are combined with a conditional thickening operation. The topology and the number of the spots are determined with the first filter, and the shape by means of the second. The algorithm is tested with a series of real mammograms, using identical parameter values for all images. The results are compared with the judgement of radiological experts, and they are very encouraging. The described approach opens up the possibility of a reproducible segmentation of microcalcifications, which is a necessary precondition for an efficient screening program.

MK-801 induced stereotypies in rats are decreased by haloperidol and increased by diazepam

The effects of haloperidol and diazepam were investigated on stereotypies (wall contacts and turn rounds) induced by the non-competitive NMDA antagonist MK-801 in rats. Haloperidol (0.03, 0.10, 0.25 and 0.40 mg/kg body weight) caused a dose-dependent antagonism whereas diazepam (3.0 and 5.0 mg/kg) caused a dose-dependent agonism of the stereotypies induced by 0.30 mg/kg MK-801 (all drugs given intraperitoneal). Conversely, diazepam (5.0 mg/kg) given alone reduced significantly the number of spontaneous wall contacts and turn rounds. The paradoxial stimulation of MK-801 induced stereotypies by diazepam could be explained by a shift between positive and negative corticostriatothalamic feedback loops envolving GABAergic neurons in favour of the former.

[Estradiol inhibits dopamine mediated behavior in rats--an animal model of sex-specific differences in schizophrenia]

We found in a representative sample of 392 first hospital admissions for schizophrenia a higher mean age at onset in females by 3.2 to 3.9 years, whereas the lifetime risk was equal for both sexes. In males the rates of onset show a steep increase reaching the maximum value in the age group 15-24 years, followed then by a steady decrease. Females reach the first peak with a clear delay between 20 and 29 years. After the decrease a second smaller peak is observed consistently in females within the age group 45-49 years and over. After having excluded alternative explanations for this gender differences (for example, diagnosis artefacts, sociocultural factors), we hypothesized that the effect of oestradiol on the dopaminergic system enhances the vulnerability threshold for schizophrenia, which is lowered again during the menopause. Alternatively we assumed that testosterone reduces the vulnerability threshold and thus furthers the earlier onset of schizophrenia in males. We tested these hypotheses in animal models by investigating the effects of the gonadal hormones on haloperidol-induced catalepsy and on apomorphine-induced stereotypies in both neonatal and adult rats. Testosterone showed no clear influence on the tested dopamine-mediated behaviour. Oestradiol caused a significant reduction on both dopamine-agonist and dopamine-antagonist induced behaviour. These effects were stronger in neonatal animals. Since oestradiol caused a 2.8-fold reduction of dopamine receptor affinity for sulpiride, we assumed that the behavioural changes caused by oestradiol were accounted for by a down-regulation of the dopaminergic system.(ABSTRACT TRUNCATED AT 250 WORDS)

An animal model for the effects of estradiol on dopamine-mediated behavior: implications for sex differences in schizophrenia

Schizophrenic women have been consistently found to have a later age of onset and a less severe clinical course of illness as compared with schizophrenic men. Because these differences are not explained by diagnostic artifacts or sociocultural factors, we tested the hypothesis that they are determined by the influence of the gonadal hormones testosterone and estradiol on dopaminergic (DA) neurotransmission. We used animal models in which the effects of the hormones on behavioral changes induced by the DA antagonist haloperidol (catalepsy) and by the DA agonist apomorphine (oral stereotypies, grooming and sitting behavior) were investigated in neonatal and in adult treated rats. No consistent effects of testosterone were observed. Estradiol significantly reduced the behavioral changes induced by both haloperidol and apomorphine, and this effect was more pronounced in neonatally treated animals. These results suggest a downward regulation of DA neurotransmission by estradiol, which is supported by the results of 3H-sulpiride binding determinations in brain homogenates from the same animals: estradiol caused a 2.8-fold reduction of DA receptor affinity to sulpiride. Our findings suggest that estradiol might act as a protective modulator in schizophrenia by enhancing the vulnerability threshold for psychosis through the downward regulation of DA neurotransmission. Such mechanism could explain, at least in part, the later onset and the more favorable course of schizophrenia in female patients.

Oestradiol enhances the vulnerability threshold for schizophrenia in women by an early effect on dopaminergic neurotransmission. Evidence from an epidemiological study and from animal experiments

In a representative sample of 392 first hospital admissions for schizophrenia from a population of 1.5 million we assessed the "true" age of onset by a semi-standardized interview "IRAOS". We demonstrated that the mean age at onset of the disease is 3-4 years higher in females than in males, with the lifetime risk being exactly equal. In males, the rates of onset show a steep increase - starting from school age and reaching their maximum value in the age group 15-24 years - followed by a steady decrease. Females reach the first peak with a clear delay between 20 and 29 years. After the decrease, a second smaller peak is observed consistently in females within the age group 45-49 years and over. After having excluded competing explanations, we hypothesized that the effect of oestradiol on the dopaminergic system enhances the vulnerability threshold, which is lowered again during the menopause. Alternatively, we assumed that testosterone reduces the vulnerability threshold and thus furthers the earlier onset of the disease in males. We tested the hypotheses in three animal models by examining the effect of gonadal hormones on haloperidol-induced catalepsy and on apomorphine-induced stereotypies in both neonatal and adult rats. No clear influence by testosterone was shown. Oestradiol caused a significant reduction of both dopamine-agonist and dopamine-antagonist induced behaviour. The effects were stronger in neonatal rats. Since oestradiol caused the dopamine (DA) receptor affinity for sulpiride to be reduced by a factor of 2.8, we assumed that the behavioural changes due to oestradiol were accounted for by a down-regulation of DA receptor sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Processing distinctions between stems and affixes: evidence from a non-fluent aphasic patient

In this paper, we study the ability of a non-fluent aphasic patient, BN, to comprehend morphologically complex words when they appear in utterance contexts. We first establish that he is insensitive to the contextual appropriateness of both derived and inflected words. In a further experiment we show that he has no difficulty processing the stems of complex words and conclude that his problem is with the bound morphemes themselves. We then ask whether this problem is due to his inability to access either the phonological form of a morphologically complex word or its semantic and/or syntactic content. We find that only the access of semantic and syntactic content is impaired. We conclude from these six studies that: (a) BN presents a counter-example to the claim that non-fluent patients have particular difficulty with those aspects of morphology which have a syntactic function; (b) BN processes both derived and inflected words by mapping the sensory input onto the entire full-form of a complex word, but the semantic and syntactic content of the stem alone is accessed and integrated into the context. The semantic and syntactic implications of the suffix are never evaluated. This implies separate representation of the stems and suffixes of some types of morphologically complex words.

The rise of blood sugar as an additional parameter in traumatic shock

Besides the known cardiovascular effects of hemorrhagic shock, regular metabolic consequences can be demonstrated in the rabbit: 1. The rise in blood sugar in hemorrhagic shock increases with the amount of blood withdrawn per unit of time. 2. The characteristic rise in blood sugar lasts longer than the phase of the partial exsanguination. 3. In traumatic shock, the rise in blood sugar indicates the degree of severity of the injury earlier than the fall in blood pressure does. The rise in blood sugar is attributable to a reflex increase in glycogenolysis due to catecholamine secretion elicited via baroreceptors in hemorrhagic shock. For the pronounced rise in blood sugar in traumatic shock, an additional receptor is postulated. Supplementary investigation of the blood sugar may possibly enable the extent of the injury to be diagnosed earlier in traumatic shock, and the negative sequelae may be reduced by timely, adequate therapy.

[Segmental fracture of the tibia]

Segmental fractures of the leg, though rare, often imply serious complications. We present a concept of management which considers the impaired circulation to fracture fragments. In our opinion plate osteosynthesis and medullary nailing should remain the exception; closed methods have priority. In open fractures external fixation devices are preferred.

[Patterns of injuries of restrained car passengers (author's transl)]

A detailed analysis of actual traffic accidents involving car passengers wearing seat belts was carried out by an interdisciplinary team. The passengers were examined for the severity of their injuries, the combination of their injuries, and the practicality of their seat belt system. The type of injury to the car, the speed, and the line of impact were related to the injuries. Incorrect use of the belt system, malfunction due to external causes, and construction defects in the seat belt system were described and evaluated according to their specific importance.

[Rescue helicopter services for emergency treatment at the scene of the accident (author's transl)]

During the last three years 3639 emergencies were dealt with using the rescue helicopter "Christoph 4" in Hannover. Of these, 89.3% were primary flights to the scene of the accident to give qualified first aid by a medical team. The average distance to the scene of the accident was 20.8 km with an average flight time of 8.5 min. 2688 patients were treated by the helicopter crew. 89.8% of the patients had injuries of a severity of NACA (National Commitee for Aeronautics) 3 and more. Intubation and artificial respiration was carried out on 293 occasions. Shock treatment with blood substitute was given in 1593 cases. 30 resuscitations at the scene of the accident were successful.

[Distribution and causes of injuries in seat belt-wearing automobile passengers]

We analized 71 car head-on collisions with 100 persons involved wearing seat belts. All 31 passengers with faulty belt function (group II) suffered injuries, 7 of them fatal. 69 passengers with correct belt function were only slightly injured if at all (group I). The majority of the injuries in group I are those of the chest and lower extremities, in group II, however, of the head and lower extremities. The "absolute degree of trauma" revealed the maximal extent of trauma for group II in the region of head, chest and pelvis/abdomen. Increased deformation of the vehicle results in an increase of severe injuries especially in passengers of group II.