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Biomedical subjects

R Hess

Publications and source records attributed to R Hess.

At least 109 records · Page 6Linked to original sources
PubMed1979

Predictive evaluation in animals of the contact allergenic potential of medically important substances. II. Comparison of different methods of cutaneous sensitization with "weak" allergens.

Results of the optimization method and of other methods used to assess contact allergy in laboratory animals were compared with known epidemiological data on the occurrence of hypersensitivity reactions in man. Tests were performed with preservatives (formalin, ethylenediamine and sorbic acid), drugs (penicillin G, Benzocaine and sulphathiazole) and other contactants belonging to widely different chemical classes (p-phenylenediamine, triclosan, pyrazole derivatives, nickel and chrome salts, eugenol, isoeugenol and mercaptobenzothiazole). The degree of sensitization achieved in guinea pigs by the optimized procedure (intradermal test with adjuvant combination) and the maximization procedure was invariably superior to that produced by the epidermal method using prior irritation of the site of application. Both the optimized procedure and the maximization test seem to be capable of identifying contact allergens that cause hypersensitivity reactions in as few as 1 in 10,000 of the human population as a whole. The optimization test merits consideration as a standardized and efficiently predictive procedure.

Adjuvants, Immunologic↗
PubMed1979

Laboratory infection of blackflies (Simuliidae) and midges (Chironomidae) by the mosquito mermithid, Romanomermis culicivorax.

Penetrating infective juveniles of Romanomermis culicivorax usually killed first-stage larvae of Chironomus maturus Johann., Chironomus sp., Simulium damnosum Theo., and S. venustum Say. Nematodes were melanized and died after they entered fourth stage larvae of 2 chironomid species, but no host reaction was evident after entry into fourth-stage blackfly larvae. In contrast, the nematodes initiated development in the latter hosts, which died before the nematodes completed their development.

Animals↗
PubMed1978

Studies on the duration of egg transport by the human oviduct. II. Ovum location at various intervals following luteinizing hormone peak.

The location of ova in the genital tract between 24 and 144 hours following the LH peak was determined in 23 normal women. Nineteen eggs were found in the Fallopian tubes between 24 and 96 hours and five eggs were recovered from the endometrial cavity between 96 and 144 hours following the LH peak. According to the present data and considering that ovulation occurs in the human subject nearly 17 hours after the LH peak, it is concluded that the transport of unfertilized ova in women is characterized by a period of retention in the ampulla, which lasts approximately 72 hours, followed by rapid transit through the isthmus and appearance of the ovum in the endometrial cavity around 80 hours after ovulation.

Adult↗
PubMed1978

Sensory denervation of the plantar lumbrical muscle spindles in pyridoxine neuropathy.

Male albino rats treated with excessive amounts of pyridoxine developed an impairment of neuromuscular function. The equatorial region of the plantar lumbrical intrafusal muscle fibres was studied in the electron microscope and the calibre of the nerve fibres was determined in semi-thin sections of the posterior tibial nerves. Degeneration of the primary sensory endings coincided with the onset of ataxia, and in more advanced stages of the neuropathy as well as after a 2-month treatment-free period the equatorial region was denervated. There was a corresponding decrease in the number of large nerve fibres. It is considered essential that primary sensory endings of lumbrical muscle spindles should be included in studies of distally accentuated sensory neuropathies.

Animals↗
PubMed1978

Temporal relationships of estrogen, progesterone, and luteinizing hormone levels to ovulation in women and infrahuman primates.

These studies were undertaken to ascertain the interval between the estrogen and LH peaks and ovulation in women, rhesus monkeys, and baboons. Estrogen, progesterone, and LH were measured by RIA. Ovulation was documented by visual examination of the ovaries, histology of the corpora lutea, and recovery of ova. The data for human subjects was based on a group of 23 normal women scheduled for surgical sterilization. Blood was drawn daily between 8:30 and 10:30 P.M. beginning on day 10 of the cycle. Surgery was performed 1 to 5 days after the LH peak. The hormonal findings were correlated with the histology of the corpus luteum. The mean interval from the estrogen peak to ovulation was 34 hours, the interval from the estrogen peak to the LH peak was 24 hours, and that from the LH peak to ovulation was 9 hours. In 46 rhesus monkey cycles and in 53 baboon cycles diagnostic serial laparoscopic examinations were initiated following the estrogen peak and repeated every 24 hours until ovulation was confirmed. The mean interval between the estrogen peak and ovulation was 34 hours in the monkey and 41 hours in the baboon. The intervals from the estrogen peaks to the LH peaks were 12 hours in the monkey and 23 hours in the baboon. The intervals from LH peak to ovulation were 22 hours in the monkey and 18 hours in the baboon. Plasma progesterone levels were significantly increased prior to the LH peak in all three species.

Adult↗
PubMed1978

Interocular transfer in individuals with strabismic amblyopia; a cautionary note.

Interocular transfer of the adaptation after effect was measured and correlated with residual binocular function for two strabismic amblyopes who represent different types of neural loss. The results indicate that for these two subjects there is paradoxical correlation between efficacy of interocular transfer and residual binocular function.

Adaptation, Ocular↗
PubMed1978

Predictive evaluation in animals of the contact allergenic potential of medically important substances. I. Comparison of different methods of inducing and measuring cutaneous sensitization.

Groups of guinea pigs were sensitized with a 0.1% solution of dinitrochlorobenzene (DNCB) by the Draize intracutaneous method. The course of the induction process, the influence of the vehicles used and the extent to which the reactions are amenable to assessment according to objective criteria were examined. The sensitivity of the standardized Draize test was then compared with that of various other sensitization techniques, including: The intracutaneous test with adjuvant (optimization test) The maximization test according to Magnusson & Kligman (1969) The epidermal sensitization test The epidermal sensitization test with prior irritation of the contact site (by croton oil or sodium lauryl sulphate). Comparison of these methods revealed that either the additional application of adjuvant or prior irritation of the contact site augmented the degree of sensitization of DNCB just as greatly as the simultaneous use of adjuvant and prior irritation of the skin, (maximization test). The improved sensitization methods, and in particular the standardized optimization test, may prove to be of particular value for the study of so-called weak allergens.

Animals↗
PubMed1978

Vision through cataracts.

Contrast thresholds for a range of different spatial frequencies were compared with "acuity" tests for 10 subjects with uniocular senile cataract. The results indicate that the magnitude and extent of the intra-resolution limit abnormality vary dramatically in cataract subjects and that, for some subjects, vision is abnormal for objects of all sizes. This finding indicates that the present acuity evaluation of vision with cataracts is inadequate because, in some cases, it grossly overestimates the nature of the visual world of the cataract patient.

Aged↗
PubMed1978

[The significance of rhythmic mid-temporal discharges (author's transl)].

Out of 50,000 EEG's those of 38 subjects contained rhythmic mid-temporal discharges (RMTD), corresponding to an incidence of 0,1%. The morphological features of RMTD are: 1. frequency: 5.5-6.5/sec 2. shape: monophasic and regular with occasionally interposed 12/sec. activity. 3. localisation: mid temporal, often spread to anterior, seldom posterior region. 4. occurence: bilateral, simultaneous, or alternating sides. They are closely linked to the drowsy state, occuring at the transition from A2 to B2 stage (IA2) and arising from a fairly desynchronized EEG. RMTD are commonly seen within REM periods, which are markedly fragmented with interspersed periods of drowsy patterns lasting 20-90 sec, during which the RMTD are seen. Occasionally they are strictly related to slow eye movements and periodic respiration. The RMTD are an individual feature, appearing in different persons with variing penetrance. Their occurence is favoured or inhibited to a certain degree by external circumstances. Slow and fast wave sleep in subjects with RMTD are disturbed. Both of them, especially the fast wave sleep are reduced in favour of markedly increased stages of drowsiness with RMTD, which sometimes last several minutes. In spite of such abnormal organisation of sleep the subjects feel recovered in the morning and sleep disturbances are not reported. RMTD could therefore be considered as "bioelectrical sleep disorder". We did not find any correlation between RMTD and clinical findings, in particular not with psychomotor or any other form of epilepsy.

Delta Rhythm↗
PubMed1977

[Drivers license qualification for epileptics].

The question whether a person with epilepsy qualified for a driving licence must be examined from the point of view of the individual as well as that of the community. The general public should be protected against unduly high risks from epileptic drivers, whereas the patient has a right to live as normal a life as possible, which includes driving an automobile. Too rigid criteria for obtaining the license increase the number of persons who evade medical control and drive "illegally". To require physicians to report their epileptic patients to the authorities would be counterproductive; it would also destroy the personal confidence between physician and patient which is so essential for successful treatment. Epileptic persons endanger safety on the road only slightly: 0.1-0.3% of all traffic accidents are due to epileptic seizures. In contrast, abuse of alcohol plays a major role in 6-9% of all accidents, whereas 80-90% are attributable to evident mistakes by the driver. Epileptic patients under regular medical supervision who are licenced on grounds of approved criteria do not cause more accidents than the general population. A dangerous group are, however, those with mental alterations (organic or reactive) and particularly patients with aggressive and expansive-compensatory traits, as well as those driving without permission. Prognostic criteria as to the further course of the disease are paramount for the assessment of qualification for the licence. The following rules have proved their worth: 2 years freedom from seizures (with or without therapy), no abnormalities specific for epilepsy in the EEG, no serious mental changes, regular medical supervision and treatment mus be guaranteed. Departures from these rules should be confined to exceptional cases with the consent of a physician specialized in epileptology. The same holds for admission to higher categories of driving licence, the only practical eventuality being category D (lorries), and even this only in rare cases. It will scarcely ever be possibel to licence a person who has at some time had epilepsy for professional passanger transportation. The attitude of the physician who first sees the seizure patient is often decisive. It is important that he recognizes the problem, objectively informs his patient and from the very outset gives him realistic advice in order to avoid false decisions, particularly regarding his professional career.

Accident Prevention↗