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Biomedical subjects

M Janko

Publications and source records attributed to M Janko.

At least 19 recordsLinked to original sources
PubMed1998

Contribution of collateral sprouting to the sensory and sudomotor recovery in the human palm after peripheral nerve injury.

The contribution of collateral sprouting to the sensory and sudomotor recovery was studied in 52 patients aged 3-66 years (mean 35.5 years) from 2 to 9 years following nerve injury and repair. The study included three groups of patients: (1) patients with complete division of median and ulnar nerves (skin reinnervation exclusively due to axon regeneration), (2) patients with isolated division of ulnar or median nerve (skin reinnervation due to axon regeneration and possible collateral sprouting), and (3) patients in whom injured axons failed to regenerate (skin reinnervation exclusively due to collateral sprouting). The end stage of sensory and sudomotor recovery was studied by: clinical methods, sensory nerve action potential (SNAP) measurements, sympathetic skin response (SSR) and the ninhydrin test. We found that recovery of sensory and sudomotor function in groups 1 and 2 was similar. End-stage sudomotor and sensory recovery within the autonomous area of the nerve did not depend on possible collateral reinnervation. Collateral reinnervation from the uninjured nerve was limited to the border innervation area of the palm and ring finger. Adjacent uninjured nerve may contribute to sprouting of nociceptive axons providing a protective function.

Action Potentials↗
PubMed1998

Role of surface EMG in diagnostics and treatment of muscle tension dysphonia.

In muscle tension dysphonia (MTD) excessive tension of both the internal and external laryngeal muscles is observed. In the present pilot study, 9 pairs of surface electrodes were used to determine the electromyographic (EMG) characteristics of different muscles in the perioral area and anterior neck before and during phonation. Eleven patients with MTD and 5 normal speakers were included within the study. The results show a 6-8-fold increase of EMG activity and/or an alternation of the EMG activity level in the perioral and supralaryngeal muscles before and during phonation in most of the patients with MTD. It is not clear whether these muscles are activated as compensation for excessive tension of internal laryngeal muscles, or whether they are responsible for some of the voice disorders.

Adolescent↗
PubMed1997

Regeneration of sudomotor and sensory nerve fibres after digital replantation and microneurovascular toe-to-hand transfer.

The end-stage sudomotor and sensory recovery in patients with replanted fingers and patients after microneurovascular toe-to-hand transfer was studied using quantitative electrophysiological investigations (recovery of sensory nerve action potentials and the sympathetic skin response), the ninhydrin test and clinical testing of sensory regeneration (light touch, pain, static and dynamic two-point discrimination). 13 adult patients with 22 replanted digits (11 males, 2 females) aged 21-58 years (mean 42.2 years) and 12 adults and adolescents (8 males, 4 females) aged 13-45 years, (mean 26.8 years) following 14 microneurovascular great and/or second toe-to-hand transfers were studied. The replanted fingers were examined 2-7 years after injury and replantation. The toe-to-hand transfers were examined 2-12 years after injury and transfer. The results show better end-stage recovery of sudomotor and sensory function following finger replantation when compared to microneurovascular toe-to-hand transfer.

Adolescent↗
PubMed1996

Sympathetic skin response and regeneration of sudomotor fibers after complete division of peripheral nerves.

Sympathetic skin responses (SSRs) were studied in hands of patients during regeneration of their median or ulnar nerves following complete severance and suture. The SSRs were elicited with electrical stimuli presented to the forearm of the normal side and recorded between the dorsum of the hand and three sites in the innervation area of the two nerves. The amplitude and area of the SSRs were compared to those obtained at the identical points on the uninjured hand. The responses were followed up for 16 months at 1-1.5-month intervals in a group of 6 adults and for 14 months at monthly intervals in 7 children. After an initial absence, the SSRs appeared after about 4 months postoperatively at the most proximal site in the adults and 2-3 months in the children. It progressed subsequently over a 14- or 16-month observation period to less than 50% of the normal side in the adults and to close to 100% in children, fastest and most complete for the proximal recording site, considerably earlier in the children. End-stage recovery studied in another group of 14 adults and 7 children 2-7 years postoperatively reached an average of 80-100% at the most proximal recording site in most adults and children. The intermediate and the distal sites showed less complete return of the SSR. The method of recording SSRs is considered suitable to follow regeneration of the sudomotor fibers in the cut and sutured nerves of the hand.

Adrenergic Fibers↗
PubMed1995

Dust mite allergens in the office environment.

The objective of this study was to evaluate the extent of dust mite infestation and its contribution to the health complaints in office settings. The methodology recommended for residential dwellings was evaluated for use in the work environment. Der p I allergen-specific ELISA was chosen as a primary method. A liquid chromatography method for guanine is suggested as a backup method to cover a few cases where other mite species may be encountered. The levels of dust mite allergens were measured in 14 offices in response to numerous health complaints. Approximately one-half of the offices investigated were identified as having a dust mite population. Four offices showed levels of Der p I in the dust greater than 1 microgram/g. In two offices, the dust mite allergens were the source of the health complaints. In the other two offices, dust mite allergens were one of the contaminants in the office environment. In all cases, the infestation of dust mites in the offices was localized to a few specific work areas. Office chairs were the primary location where dust mites thrived. The remedial measures included regular cleanup of all fabric-covered office furnishings. Steam cleaning was recommended to eliminate dust mite populations.

Air Pollution, Indoor↗
PubMed1992

Occupational exposure to 1,6-hexamethylene diisocyanate-based polyisocyanates in the state of Oregon, 1980-1990.

Monitoring of exposure to 1,6-hexamethylene (HDI) monomers and HDI polyisocyanates in Oregon was initiated in 1980 and covered primarily spray painting and related activities. A total of 562 air samples were collected from 60 workplaces during the years 1980-1990 and analyzed for HDI and HDI polyisocyanate content. Of the total, only a small fraction (6%) of the samples exceeded the state of Oregon permissible exposure limit (PEL) of 0.02 ppm for HDI monomer; however, a much higher number (42%) of the samples exceeded the Oregon PEL of 1 mg/m3 for HDI polyisocyanates. Spray finishing operations were divided into three categories: continuous industrial spraying, auto body repair shops, and intermittent spray operations of large objects. The highest exposures among all three categories for both HDI and HDI polyisocyanates were measured during spray finishing. The geometric mean for HDI in the industrial spray operations was 0.001 ppm and for HDI polyisocyanates was 3.78 mg/m3. Frequently, the peak exposures exceeded the Oregon PEL for polyisocyanates, reaching as high as 12.2 mg/m3. In auto body shops, the mean for HDI was 0.002 ppm and for HDI polyisocyanates was 1.60 mg/m3 with peak concentrations of 0.049 ppm for HDI and 18.4 mg/m3 for HDI polyisocyanates. In the third category of spray finishing of large objects, the geometric means for three subcategories ranged from 0.001 to 0.017 ppm for HDI with a peak concentration of 0.069 ppm. The geometric means for HDI polyisocyanates ranged from 2.09 to 15.9 mg/m3 with a peak of 29.5 mg/m3. In all the surveys, the ventilation facilities and personal protective equipment were evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyanates↗
PubMed1990

The bulbocavernosus reflex. A single motor neuron study.

Reflex latency variability was established for single motor neuron discharges in the bulbocavernosus reflex, as elicited by electrical stimuli to the dorsal penile nerve and recorded by a single fibre EMG electrode in the bulbocavernosus muscle. Whereas many reflex responses had a rather large latency variability of above 1000 microseconds (expressed as SD of mean latency) there was a group of motor neurons with a variability of around 500 microseconds. Single motor neuron reflex responses with shorter latencies tended to show less variability. No habituation of single motor neuron reflex discharges was observed on prolonged regular repetitive stimulation. Both absence of habituation and the relatively low latency variability of bulbocavernosus reflex responses for single motor neurons suggest similarities between this reflex and the first component of the blink reflex; we postulate that the shortest bulbocavernosus reflex pathway is oligosynaptic.

Adult↗
PubMed1989

Occupational exposure and analysis of microcrystalline cristobalite in mullite operations.

Three analytical methods currently used for crystalline free silica determination in occupational exposure samples were evaluated for their applicability to ceramic materials containing synthetic mullite. X-ray powder diffraction is the only method that can be used with sufficient precision and potentially adequate accuracy for occupational exposure monitoring. Personal respirable dust exposure samples were collected in two foundries. The results of exposure evaluations in Plant A showed overexposure to the dust, particularly in the shakeout area. The cristobalite concentration in the respirable dust exceeded that in the original material for this particular area. This may be related to the preheating of molds to more than 1100 degrees C for the pouring of stainless steel castings, causing conversion of some of the colloidal silica binder to cristobalite, and related to high vibration fracture of the material during removal of castings from molds. In Plant B, quartz was sometimes present along with cristobalite in personal samples. Respirable dust levels exceeded the Occupational Safety and Health Administration's (OSHA) permissible exposure limit (PEL) and the National Institute for Occupational Safety and Health's (NIOSH) recommended time-weighted average (TWA) for crystalline free silica, indicating a need for better engineering controls to reduce dust levels. The inadequacy of reference standards currently available for cristobalite analysis in these types of materials is cited. The need for more toxicological research is emphasized.

Aluminum Silicates↗
PubMed1989

Fasciculations in motor neuron disease: discharge rate reflects extent and recency of collateral sprouting.

Single fibre EMG recordings were made from 152 fasciculating motor units in 17 patients with motor neuron disease. All recordings showed abnormal jitter, many (75%) displayed intermittent blocking, and most had abnormal fibre density (mean 4.3), demonstrating considerable degrees of collateral sprouting supported by the fasciculating motor units, and varying degrees of functional immaturity of the new axonal twigs and the motor end plates. The SFEMG abnormalities reflecting both the degree and the recency of collateral reinnervation correlated with the mean interdischarge interval, suggesting that the properties of the generator site depend on the functional state of the fasciculating motor unit as a whole.

Adult↗
PubMed1983

Flexion withdrawal reflex as recorded from single human biceps femoris motor neurones.

Reflex responses were elicited in the biceps femoris muscle of patients with cervical spinal cord lesions by stimulating the sural nerve and recording from single motor neurones by single fibre EMG technique. The consecutive responses within the surface-recorded early component displayed a latency jitter between 500 and 600 microsec (S.D.), suggesting an oligosynaptic reflex arc. These responses were rarely seen; they were suppressed by increasing the stimulus strength. The surface-recorded late component consisted in the single fibre EMG recordings of repetitive discharges of individual motor neurones. The latency jitter of the earliest of these discharges was about 1440 microsec, and it progressively increased in the later discharges, reflecting increasingly more variable central conduction time. Ischaemia of the leg made some of the late discharges at a latency of about 0.5 sec remarkably stable and reduced their jitter. They may represent responses to the activity of slowly conducting afferent fibres, normally suppressed by inflow along the fast conducting fibres. Stimulation of dorsal columns through epidurally placed electrodes at T1 and T2 levels resulted in a complete suppression of repetitive discharges, outlasting the actual stimulation. TENS and light stroking of the skin below the level of the spinal cord lesion, as well as subthreshold stimuli to the sural nerve, had a similar effect. These results suggest that the late component of the flexion reflex may share some of the neural mechanisms responsible for feeling pain.

Electric Stimulation↗
PubMed1983

Direct and reflex responses in perineal muscles on electrical stimulation.

Responses in the external anal and urethral sphincters as well as in the bulbocavernosus muscle have been evoked by supramaximal electrical stimulation of the penis (or clitoris), perineum and the peri-anal region and recorded electromyographically in 82 male subjects 5 to 73 years old and in nine female subjects 18 to 55 years old, who had no systemic diseases or demonstrable sacral nervous system lesion. On perineal stimulation (including the penis or clitoris) reflex responses with a typical latency of 33 ms and which exhibit no habituation were obtained in all muscles examined. Stimulation of the peri-anal region gave habituating reflex responses with a typical latency of 55 ms in all muscles examined. On perineal, and sometimes also peri-anal stimulation, stable short latency responses with typical latencies of 5 and 13 ms were recorded; both were considered to be direct responses. The different evoked muscle responses obtained by stimulation in the perineal and peri-anal region have to be distinguished when the bulbocavernosus and anal reflexes are recorded for evaluation of sacral nervous system lesions.

Adolescent↗
PubMed1982

EMG, single fibre EMG and sacral reflexes in assessment of sacral nervous system lesions.

EMG of pelvic floor muscles, single fibre EMG of external anal sphincter and both bulbocavernosus and anal reflexes were investigated in 31 men without sacral nervous system lesions and in 12 patients with neurogenic erectile impotence, of whom one had slight loss of sensitivity to pinprick in the lower sacral dermatomes. EMG and single fibre EMG abnormalities have been found concomitantly in eight patients and six of these had also prolonged bulbocavernosus reflex latencies. In two patients the prolonged bulbocavernosus reflex latency was the only abnormality. Single fibre EMG of anal sphincter muscle seems to be superfluous in routine evaluation of sacral nervous system lesions.

Adolescent↗
PubMed1976

Nerve regeneration following primary repair.

In nine selected cases a primary nerve repair was done. In all these patients a special suture was used. Applying clinical and neurophysiological tests, regeneration of the motor and sensory nerve fibres was followed for two years. A remarkable difference in growth rates of sensory and motor nerve fibres was observed. The average rate of growth of sensory nerve fibres was 5 mm a day, and of motor nerve fibres it was 1.7 mm a day. At the end of a two years' interval after operation, good recovery from the initial muscular atrophy was observed in all but two cases. Function of previously denervated muscles was nearly normal. Discrimination of points 4-10 mm apart was possible. Normal terminal conduction times along motor nerve fibres were found in five cases. Slightly prolonged times were found in four. Calculated conduction velocities in sensory nerve fibres were half to three quarters of normal times. All patients resumed their previous occupations.

Axons↗