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Biomedical subjects

J Van Hees

Publications and source records attributed to J Van Hees.

At least 19 recordsLinked to original sources

Effect of the life-span of female Glossina palpalis gambiensis on the weight and size of its progeny.

Pupae and teneral flies of Glossina palpalis gambiensis originating from three successive reproductive cycles were compared for their size and weight. In general, pupal weight and fly weight increased, whereas fly size, measured as wing vein length, decreased with the number of reproductive cycles. The linear regression observed between weight and wing vein length of the fly demonstrated that, particularly for flies originating from the first and second larvipositions, small changes in wing vein length reflected substantial differences in weight. The results of these laboratory experiments were compared with some field data on Glossina morsitans from Zambia and related literature. The life span of the female tsetse, affecting the size of her progeny, could clarify partially some of the field observed seasonal changes in size, whereas the correlation between fly size and weight could eventually explain the differential mortality of some size classes of tsetse flies. However, whether these laboratory observations can be extrapolated to the field has still to be confirmed.

Animals

Peripheral cutaneous nerve distribution to the fingers.

Both sensory distribution charts and the unaffected side, are used as reference points in the assessment of cutaneous innervation. Sensory nerve conduction studies, in particular, often use comparison between sides. However, remarkable differences can be found between various sensory innervation maps, and no evidence was found in the literature for the assumption that the pattern of cutaneous sensory distribution of the peripheral nerves between the left and right limbs is symmetrical. The purpose of this study was to investigate variations in the sensory innervation of the fingers by means of a neurophysiological method, and to compare the results for the left and right hands. The subjects of this study were 31 young women. Percutaneous peripheral nerve stimulation was performed on the four nerve branches providing sensory innervation to the fingers, and action potentials were sought from the fingers by use of annular surface electrodes. Variations in the cutaneous innervation of the fingers between individuals often occurred and were found more frequently on the dorsal than the palmar aspect. The distribution of sensory innervation may even differ markedly between hands in the same individual. The cutaneous innervation of all peripheral nerves supplying the fingers may differ from the innervation patterns described in the various distribution charts. Prudence is called for when applying sensory distribution charts as absolute references for the assessment of cutaneous sensation in patients. Caution should also be applied when comparing one hand with the other when assessing the cutaneous innervation of the fingers.

Action Potentials

Pathological findings in a patient with amyotrophic lateral sclerosis and multifocal motor neuropathy with conduction block.

We studied a 53-year-old woman with progressive weakness of the left arm, gradually spreading to the other limbs. Neurological examination revealed a motor neuron syndrome with paresis, fasciculations and atrophy. Electrophysiological studies showed multiple motor conduction blocks. The anti-GM1 IgM titer was elevated. The patient was thought to have a multifocal motor neuropathy. Despite intravenous cyclophosphamide treatment, however, she died with respiratory insufficiency. On postmortem examination, the brachial plexus showed patches of demyelination underlying different areas of motor conduction block. The spinal cord, however, revealed severe neuronal loss in the ventral horn and axonal loss in the corticospinal tract, indicative of amyotrophic lateral sclerosis. Demyelination of peripheral nerves could have been responsible for the other conduction blocks in this patient. The prominent degeneration of motor neurons, however, must also have played a role in the clinical picture. Some patients with the syndrome of a multifocal motor neuropathy may have MND rather than, or in addition to, a demyelinating peripheral motor neuropathy.

Action Potentials

[Experimental infection of Glossina morsitans morsitans (Mall) with Trypanosoma congolense (ZRE/G143/90). Parasite cycle and vector competence in the tsetse fly].

This report presents an experimental study of the life cycle of Trypanosoma congolense (ZRE/G 143/90) in relation to the vectorial competence of Glossina morsitans (Mall). The rate of engorgement at the time of an infectious meal and the mortality before day 15 of the life cycle were not significantly different between male and female flies. The mesocyclic forms of trypanosomes were regularly observed in the proventriculus, crop duct, oesophagus, cibarium and proboscis, except in the crop. On day 12 of the cycle, epimastigote forms were predominant in the proboscis. On day 13 of metacyclogenesis, four out of six rats (67%) used for feeding the flies were positive for trypanosomes upon buffy coat examination. These results demonstrate the short incubation period of trypanosomes in the vertebrate host and precociousness of the vectorial competence of some individuals of G m morsitans (Mall). Among the three cyclic stages, only the procyclic forms in the intestine showed a significant difference between the sexes, the male flies being more infected than the females. Metacyclogenesis undergoes three cleavages leading to the successive and permanent establishment of the procyclic, mesocyclic and metacyclic forms in the midgut, proventriculus and proboscis respectively.

Animals

Effect of a fermented infant formula containing viable bifidobacteria on the fecal flora composition and pH of healthy full-term infants.

We assessed the growth, tolerance, and acceptability as well as fecal flora composition and stool pH of 20 healthy full-term infants fed with a fermented whey-adapted infant formula containing viable bifidobacteria (10(6)/g of powder) during the first 2 months of life. This fermented infant formula, first biologically acidified by Streptococcus thermophilus and Lactobacillus helveticus, was compared to a whey-adapted, nonacidified, low-phosphate infant formula in a double-blind, randomized controlled study. The results were compared to a control group (n = 14) of fully breast-fed infants. The fermented whey-adapted formula containing viable bifidobacteria induced a prevalence of colonization with bifidobacteria at 1 month of age similar to that of breast-fed infants (12/20 versus 8/14) but significantly higher than in the group fed the standard infant formula (4/20). The mean bacterial count of bifidobacteria was similar in all colonized infants; however, fecal pH was significantly lower in the breast-fed infants than in the nonacidified bottle-fed infants. This kind of infant formula was well tolerated and promoted a normal growth during the first 2 months.

Bifidobacterium

[Standardization and evaluation of a manual salivation method for the detection of Trypanosoma infection in the tsetse fly (Diptera: Glossinidae)].

Two methods of salivation of tsetse flies, namely manual salivation and method of Bruce et al. were simultaneously evaluated on 1,702 male uninfected Glossina palpalis palpalis (Zaire), G. palpalis gambiensis (Bobo-Dioulasso), G. p. gambiensis (Maisons-Alfort) et G. morsitans morsitans (Mall) fasted for 23, 48 and 72 hours. The risk of salivation was 0.66 by the manual method and 0.01 by the method of Bruce et al. The manual salivation method was standardised on 79 male G. m. morsitans (Mall) infected with Trypanosoma congolense IL 1180. By this method, 70.88% of flies carrying mature and/or immature infection were identified. A clear difference was observed in the proportion of tsetse flies which salivated after 72 hours and those which salivated after 48 and 24 hours of fasting.

Animals

Further evidence for myelinated as well as unmyelinated fibre damage in a rat model of neuropathic pain.

A mononeuropathy, produced by ligation of the sciatic nerve in rats, has recently been proposed as an animal model of experimental pain and pain-related disorders (hyperalgesia and allodynia). We investigated quantitatively the morphological changes in myelinated and unmyelinated fibres of the sciatic nerves 2 weeks after ligation in rats exhibiting allodynia to thermal stimulation. There was a marked reduction in the number of large myelinated fibres distal to the ligature (711 +/- 34 compared with 5315 +/- 230 in normal nerves). We also found a significant loss of small myelinated fibres (2429 +/- 109 compared with 3197 +/- 308 in normal nerves), the remaining fibres of this type showing pathological properties. Finally, ultrastructural evidence of damage to unmyelinated fibres was found. The typical pattern of large clusters of normal unmyelinated axons was no longer present within most regions of the nerve. There was a significant reduction in the size of the unmyelinated fibres (0.41 micron +/- 0.15 compared with 0.71 micron +/- 0.08 in normal nerves), together with a twofold increase in their number per cluster. Hypotheses about the mechanism of thermal allodynia in this pain model therefore must take into account the fact that all fibre classes show pathological changes.

Animals

Magnesium deficiency as a cause of acute intractable seizures.

Clinical and experimental investigations have shown that magnesium depletion causes a marked irritability of the nervous system, eventually resulting in epileptic seizures. Although magnesium deficiency as a cause of epilepsy is uncommon, its recognition and correction may prove life-saving. Two case reports are presented which emphasize the importance of recognizing hypomagnesaemia in patients with acute intractable seizures.

Adult

[Vectorial capacity of Glossina palpalis gambiensis (Bobo Dioulasso) for Trypanosoma brucei brucei EATRO 1125].

A total of 440 teneral Glossina palpalis gambiensis received one single bloodmeal on a guinea pig infected chronically with Trypanosoma brucei brucei EATRO 1125. Metacyclic infections were present in 11.29% of the flies, in 2.32% infections were limited to procyclical stages. No significant difference in vectorial capacity was observed between male and female flies, the level of metacyclic infections being 13.19% in the former and 9.55% in the latter. The parasitaemia level, the percentage of stumpy forms at the moment of the blood meal and the maintenance conditions of the flies seemed to influence the infection of the flies.

Animals

Polyneuropathy in lithium intoxication.

Two patients developed acute sensorimotor polyneuropathy after intoxication with lithium carbonate. Nerve conduction studies, electromyography, and sural nerve biopsy proved it to be an axonal neuropathy. Recovery of muscle strength, reflexes, and sensory function started weeks after discontinuation of lithium therapy. One patient fully recovered within a year. In the literature we found nine other cases of lithium polyneuropathy.

Adult

Painful muscle spasms complicating algodystrophy: central or peripheral disease?

A 21 year old female patient developed Südeck's atrophy of the right foot secondary to a chronic Achilles tendinitis. The condition was complicated by the occurrence of painful muscle spasms in the right leg and incontinence of urine. The spasms had characteristics of both a tonic ambulatory foot response and a spinal flexor reflex. The movements disappeared during sleep. Regional anaesthesia of the right leg made the spasms disappear both in and outside the region of anaesthesia. Backaveraging of the EEG showed the involuntary spasms to be preceded by a cortical potential similar to a readiness potential, indicating a cortical potential similar to a readiness potential, indicating a cortical component in the pathophysiology of the muscle spasms complicating Südeck's atrophy.

Adult

Transfer factor therapy in multiple sclerosis: a three-year prospective double-blind clinical trial.

One hundred five patients with MS were divided into three groups matched for age, sex, and disability, and treated with either placebo, transfer factor prepared from leukocytes of random donors, or transfer factor from leukocytes of family members living with the patients. There were no differences in the three treatment groups for changes in disability, activities of daily living, or evoked potentials. Eighteen months of transfer factor therapy had no effect on gamma-interferon production or natural killer cell activities.

Activities of Daily Living

Histochemical changes of substance P, FRAP, serotonin and succinic dehydrogenase in the spinal cord of rats with adjuvant arthritis.

Various histochemical changes were found in spinal segments L4-L5 of rats with adjuvant arthritis, predominantly 30 days after inoculation. A slight to marked increase of substance P immunoreactivity occurred in laminae I, II and X. FRAP activity was enhanced in lamina II. Serotonin immunoreactivity was heavier in laminae I, VIII and IX in a few animals. The intensity of the histoenzymological reaction for succinic dehydrogenase increased in certain laminae VIII and X neurons. At day 15 of the disease the increase of substance P and FRAP activities was chiefly restricted to the medial portion of the superficial dorsal horn. There was a significant positive correlation between the scratching behaviour of arthritic rats and the substance P immunoreactivity in laminae X and I. If one accepts that scratching is pain-related, the data are consistent with a possible role of substance P in the chronic pain associated with adjuvant arthritis. They leave undetermined the significance of the other histochemical changes.

Acid Phosphatase

Suppression of C-fibre discharges upon repeated heat stimulation may explain characteristics of concomitant pain sensations.

Nociceptors with unmyelinated axons were recorded from the superficial radial nerves of 7 volunteers. A sequence of uniform radiant heat stimuli of 18 s duration, starting from an individually adjusted adapting temperature were used to raise the skin surface temperature by 6 degrees C to a painful level (41-43 degrees C). These stimuli followed each other at 3 different interstimulus intervals of 35 s, 70 s and 105 s, occurring in a random order. The subjects were asked to track the time course of the stimulus-evoked sensation by manipulating the length of a light bar. Adaptation and stimulus temperatures were chosen to induce sensations of heat and/or pain. All nociceptors studied responded to these stimuli with a phasic response of 3-5 s duration, often followed by a low frequency tonic discharge, lasting as long as the stimulus. No discharges were seen in interstimulus periods. Discharge rates during the phasic responses were linearly related to interval duration, whereas tonic discharges were not influenced by the preceding interval. In parallel readings of pain responses were lower up to the 10th second of the stimulus after short rather than after long intervals. These results indicate that the suppression of C-fibre nociceptor discharges during repetitive stimulation may explain concomitant reductions in the magnitude of human pain sensations.

Adult

ERPs associated with decisions based on slowly increasing warm and painful stimuli.

The event-related potential (ERP), produced by subjects who were experiencing a gradually increasing heat stimulus, was recorded 3.5 sec before and 1 sec after a motor response. Subjects responded when the stimulus was 'just warm,' 'just at prickling pain' or 'above the temperature of just prickling pain.' Two control procedures mimicked the readiness potential (RP) and motor potential (MP) experiments. The results showed that the steadily rising negative MP was modified to a positive wave before the decision of 'warm.' During the 'pain' and 'above pain' conditions, the pre-decision slow wave was less negative than the MP but less positive than that of the 'warm' condition. A temperature control condition confirmed that rising temperature alone did not produce these results. Principal components analysis confirmed these differences by producing factors which were interpreted as representing the ERPs of the conditions of 'warm,' 'pain,' 'above pain,' RP and MP. It was evident from pilot studies that uncontrolled electrical activity from the skin potential response (SPR) was contaminating the results. SPR forced all ERP curves in the positive direction and several attempts to eliminate the SPR from the ERP data failed. While the SPR was produced differentially across conditions and across the experimental session, the smaller the variability in the electro-oculogram (EOG) recorded from above and below the orbits, the smaller was the SPR contamination that we recorded in the ERP. Therefore, we selected subjects for this experiment who showed a stable orbital EOG.

Adult