Further characterization of the binding site for [35S]t-butylbicyclophosphorothionate in locust ganglia membranes.
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Animals↗
Biomedical subjects
M C Brown
Publications and source records attributed to M C Brown.
Morphology of labeled afferent fibers in the guinea pig cochlea.
Cochlear afferent and efferent fibers in the guinea pig were labeled by focal extracellular injections of horseradish peroxidase into the spiral ganglion of the basal turn. The morphology and pattern of termination of these fibers were studied by light microscopy. Fibers labeled by injections into the peripheral side of the ganglion could be grouped on the basis of their courses and terminations in the cochlea into two classes of afferent fibers, two classes of efferent (olivocochlear) fibers, and other presumably autonomic fibers. This paper describes the characteristics of labeled afferent fibers and their parent ganglion cells. Peripheral afferent fibers were grouped into two major classes: thick (mean diameter 1.7 micron) radial fibers projecting in a primarily radial fashion from the spiral ganglion and terminating on single inner hair cells and thin (mean diameter 0.5 micron) outer spiral fibers that spiral basalward in the organ of Corti to terminate on outer hair cells, usually in one row. For outer spiral fibers, the number of outer hair cells contacted and the length of the terminal region depend on the row of outer hair cells contacted, with third-row fibers forming, on the average, the most extensive region of termination. Within the spiral ganglion, two types of ganglion cells could be distinguished: type-I ganglion cells of large size (mean soma area = 216 microns 2) with a ratio of central process diameter to peripheral process diameter greater than one and type-II ganglion cells of smaller size (mean soma area = 100 microns 2) and a central to peripheral process ratio near one. In three cochleae in which injections were made central to the ganglion, 11 type-I ganglion cells have been traced to radial fibers contacting inner hair cells and eight type-II ganglion cells have been traced to outer spiral fibers contacting outer hair cells. Thus the afferent innervation of the guinea pig cochlea is similar to the pattern described in other mammals, in which there is separate innervation of the inner and outer hair cells by the two types of ganglion cells. The central axons of both types of ganglion cells were traced individually through serial sections of a block of tissue containing the cochlea, the auditory nerve, and the cochlear nucleus. They followed similar courses in the auditory nerve, and the axons followed into the cochlear nucleus bifurcated in similar regions of the interstitial portion.(ABSTRACT TRUNCATED AT 400 WORDS)
Afferent Pathways↗
Morphology of labeled efferent fibers in the guinea pig cochlea.
Efferent axons to the guinea pig cochlea were labeled by extracellular injections of horseradish peroxidase into the intraganglionic spiral bundle within the spiral ganglion. The terminal fibers formed by these axons were classified according to their patterns of termination within the basal turn of the cochlea. A class of terminal fibers designated "autonomic" forms a highly branched plexus in the osseous spiral lamina but does not enter the organ of Corti. The termination of single autonomics includes blood vessels as well as areas of the osseous spiral lamina not adjacent to blood vessels. Two major classes of efferent axons from the olivocochlear bundle enter the cochlea by way of the vestibulocochlear anastomosis and terminate either in areas near inner hair cells (IHC efferents) or onto outer hair cells (OHC efferents). The IHC efferents have thin axons throughout their course within the cochlea and can be divided into two subclasses. The most numerous subclass of IHC efferents (unidirectional) enters the inner spiral bundle and turns to spiral in only one direction for less than 1 mm and then forms a discrete termination including many en passant and terminal swellings that are within both the inner and tunnel spiral bundles. A less common subclass of IHC efferents (bidirectional) bifurcates upon entry into the inner spiral bundle to send branches both apically and basally. These terminal fibers take spiral courses that are greater than 1 mm in extent, often course in the tunnel spiral bundle for a large portion of the spiral, and form terminals throughout their extended spiral course. None of the IHC efferent fibers send branches to cross the tunnel to innervate the outer hair cells. A second major class of olivocochlear fibers, OHC efferent fibers, forms large boutons on the outer hair cells, and although they sometimes spiral beneath the IHCs for some length, they do not give off terminals to this region. The OHC efferent axons are thick and myelinated as they enter the cochlea, and they branch near the spiral ganglion to form several terminal fibers. Some of these terminal fibers are thin as they travel from the intraganglionic spiral bundle across the osseous spiral lamina to the organ of Corti, whereas others are thick and obviously myelinated as far peripheral as the habenula.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
The macrophage response to central and peripheral nerve injury. A possible role for macrophages in regeneration.
Using mAbs and immunocytochemistry we have examined the response of macrophages (M phi) after crush injury to the sciatic or optic nerve in the mouse and rat. We have established that large numbers of M phi enter peripheral nerves containing degenerating axons; the M phi are localized to the portion containing damaged axons, and they phagocytose myelin. The period of recruitment of the M phi in the peripheral nerve is before and during the period of maximal proliferation of the Schwann cells. In contrast, the degenerating optic nerve attracts few M phi, and the removal of myelin is much slower. These results show the clearly different responses of M phi to damage in the central and peripheral nervous systems, and suggest that M phi may be an important component of subsequent repair as well as myelin degradation.
Animals↗
A reassessment of the accuracy of reinnervation by motoneurons following crushing or freezing of the sciatic or lumbar spinal nerves of rats.
The accuracy of reinnervation in peripheral nerves following second degree injuries, which do not disrupt the longitudinal continuity of the endoneurial sheaths, has been studied in rats. The sciatic nerve or lumbar spinal nerves (that is the extraspinal nerves before their fusion in the sciatic plexus) were crushed with fine watchmakers' forceps in neonatal and adult rats. In addition, the lumbar spinal nerves were frozen in a group of 5 adult rats. After allowing reinnervation to occur for 5 to 9 weeks, the motoneurons whose axons ran in the plantar nerve were labelled retrogradely with horseradish peroxidase. Their positions in the grey matter of the lumbar spinal cord were recorded and compared with those labelled from the contralateral unoperated plantar nerve. Very few errors of projection occurred after a crush lesion of the adult sciatic nerve but all the other lesions produced significant numbers of errors. The order, starting with the preparations with fewest errors was as follows (numbers in brackets = percentage of neurons misplaced): sciatic crush in adult (3%), sciatic crush in neonate (23%), spinal nerve freeze in adult (23%), spinal nerve crush in adult (35%), and spinal nerve crush in neonate (72%). It seems that a significant number of axonal growth cones cross endoneurial sheaths after crush or cryoinjuries. Explanations for the difference in observed reinnervation accuracy between young and old rats and between lesions in peripheral nerves and spinal nerves are discussed. The first is that axons in peripheral nerves in older rats have a less penetrable endoneurial membrane encasing them. The second is that the amount of misrouting is the same at all lesion sites but is much less easily detectable after sciatic lesions than spinal nerve lesions. This is because axons are organized in a 'musculotopic' manner in peripheral nerves and exchange of axon positions will occur largely between axons destined for the same peripheral target. In contrast, exchange of positions of axons in spinal nerves will lead to more overt errors because at this site axons destined for particular muscles do not lie side by side but are intermingled with axons innervating other peripheral targets.
Animals↗
Quantification of urine loss by weighing perineal pads. Observation on the exercise regimen.
Two variations on a test for quantifying urine loss in patients with urinary incontinence were compared. In the first series (Padtest 1), 335 patients underwent a 2-h pad weighing test. A fluid load of 1 litre was administered and followed 1 h later by six separate exercises, each lasting 10 min. One of six sanitary towels was worn during each exercise. Each pad was weighed before and after use to provide information about the severity of the incontinence. In the second series (Padtest 2), 104 patients were studied. The test took the same format but the exercises were rearranged in an attempt to provide information about the importance of the individual exercises. Hand washing was found to be a very provocative test both in women with unstable and those with stable bladders. The order in which the exercises were performed did not influence the overall identification of incontinence in the 2-h test period, and this supports the conclusion that the optimum length of the test is 2 h.
Female↗
Vaginal pressure as an index of intra-abdominal pressure during urodynamic evaluation.
Vaginal pressure was measured using balloon catheters in 20 patients and open-ended fluid-filled catheters in another 21. The results showed excellent correlation between vaginal, vesical and rectal pressures in response to changes in abdominal pressure.
Abdomen↗
Accuracy of reinnervation of rat internal intercostal muscles by their own segmental nerves.
The positions of internal intercostal motoneurons within their motor pool were studied, following reinnervation of the intercostal muscles by their original nerves. Six to 9 weeks after proximal nerve section in 10-d-old and adult rats, 0.1 microliter injections of wheat germ agglutinin (WGA)-HRP were made in the distal part of the reinnervated internal intercostal muscle. The corresponding region of the contralateral control muscle was also injected. The positions of the retrogradely labeled motoneurons were mapped in 100 microns transverse sections of thoracic spinal cord that had been stained for HRP according to the method of Mesulam (1982). In normal rats, motoneurons innervating distal muscle fibers are found largely in the more dorsal part of the internal intercostal motoneuron pool (Hardman and Brown, 1985). In adult rats, regenerated motor axons did not show any selectivity; distal muscle fibers were innervated by motoneurons whose cell bodies were distributed throughout the internal intercostal pool. However, in rats operated on at 10 d of age, distal intercostal muscle fibers were reinnervated by motoneurons that were distributed mainly in the dorsal part of the motor pool. These results support the view that positional signals may be of importance in organizing the distribution of axon terminals within muscles during development.
Aging↗
Diets of Asian pregnant women in Harrow: iron and vitamins.
In a study of the Asian pregnancy, the dietary intakes of 813 Asians and 54 Europeans living in Harrow were compared. Results of calculation of intakes of iron and vitamins are presented in this paper. The key findings were that vitamins D and B12 intakes were markedly lower amongst the Asians, particularly the Hindu vegetarians. Asians had lower intakes of other vitamins but these levels are unlikely to lead to deficiency and therefore not relevant in clinical terms. The Hindu vegetarians can be regarded as a fairly homogenous group with differences occurring within the group only in vitamin B12 intake. From the nutritional data it appears unnecessary to advocate any change in the Gujarati diet other than supplementation with vitamin D.
Asia↗
PREPARED for pregnancy: a counseling guide.
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Diet↗
Screening of the bladder base and urethra using linear array transrectal ultrasound scanning.
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Adult↗
Physiology and anatomy of single olivocochlear neurons in the cat.
A surgical approach to the cat's VIIIth nerve has been developed which allows recordings to be made from efferent fibers of the olivocochlear bundle (OCB) as well as primary afferent fibers, without compromising the acoustic responsiveness of either ear. The designation of OCB fibers as those with regular interspike intervals was confirmed in five cases by intracellular labeling with horseradish peroxidase. Labeled fibers could be traced centrally to somata in the superior olivary complex and peripherally to large endings on outer hair cells. The locations of the labeled neurons are consistent with a classification as cells of the medial olivocochlear system [Warr and Guinan (1979): Brain Res. 173, 152-155]. Within the cochlea, efferent neurons branched profusely to innervate as many as 84 outer hair cells over as much as 2.8 mm of the organ of Corti. Efferent units had tuning curves which were similar to those of primary afferents, although most were somewhat more broadly-tuned than afferents from the same animal. The cochlear region innervated by an efferent neuron was always close to the place where afferent fibers of the same characteristic frequency (CF) would be found. Most efferents (89%) were excited by only one ear and showed no spontaneous activity. Neurons with an ipsilateral response (n = 3) had cell bodies in the contralateral brainstem and vice versa (n = 2). Binaural units (none of which were labeled) often had spontaneous discharge and were generally restricted to low-CF regions. Differences between low- and high-CF units, which cut across the monaural/binaural distinction, were seen in the dynamic range and minimum latency. Interanimal differences seen in the responses of the efferent neurons may be related to differences in the level of anesthesia.
Acoustic Stimulation↗
Analysis of the pattern of urine loss in women with incontinence as measured by weighing perineal pads.
Three hundred and thirty-five women with urinary incontinence underwent a pad-weighing test for quantifying urine loss. Each one wore a series of pre-weighed sanitary towels for a total of 1 h. The pads were weighed again after use. The test results gave information about the severity of the incontinence which was not easy to obtain either from patient interview or from clinical examination. The type of activity was the main factor determining urine loss, although patients with detrusor instability lost more on average than the others. Voiding during the test period did not appear to influence the overall test results. Reproducibility of the test has been studied in 50 patients.
Adult↗
Controls for flow cytometers in hematology and cellular immunology.
The necessity of using freshly prepared biological samples to control and calibrate flow cytometers has impeded the utilization of flow cytometry in the clinical laboratory where regulations demand careful control calibration and yet workload and technician training militate against the preparation of specialized control samples. For a number of years, cell preparations with stabilized properties have been used routinely in hematology laboratories to evaluate the daily performance of automated blood cell counters including optical flow cytometers. Unfortunately, the stabilized preparations do not necessarily duplicate many important aspects of whole blood, resulting in variable performance of a given control preparation on different types of instrumentation. The new generation of hematology analyzers measures a host of new parameters and will require more sophisticated controls for these enhanced parameters. Some practical aspects of present and future hematology controls will be discussed. Immunology, a new area for automated cell analysis, can benefit greatly from controls both for instrument performance and for cell staining. Up to this time there has been little availability of control materials suitable for clinical immunology. We have been evaluating fluorochrome-stained cell nuclei for use as an instrument control and for calibration of immunofluorescence analyses. Our development and use of this type of control will be described. We will also discuss approaches and experiments aimed at producing cells with stabilized antigenic properties which can be stained with monoclonal antibodies and can thus act as actual reagent controls.
Antibodies, Monoclonal↗
Health care financing and the Canada Health Act.
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Canada↗
Foley catheter technique for hysterosalpingography: potential diagnostic error.
The pressure drop which occurs along a narrow Foley catheter used for hysterosalpingography has been measured for radio-opaque contrast media of different viscosity. The difference between the applied pressure and the pressure developed within the uterus is sufficient to mislead the operator in some cases.
Adult↗
Spatial organization within rat motoneuron pools.
Topographical maps form the basis of the organization in many projections within the central nervous system, but in the neuromuscular system such detailed spatial organization has generally been assumed to be absent and indeed unnecessary for normal function (see, for example, ref. 1). However, there is some physiological evidence for a degree of spatial organization within the discrete, longitudinal motor columns which supply individual muscles. We have used horseradish peroxidase as a retrograde tracer to confirm the topographical relationship between the rostro-caudal location of motoneuron cell bodies and the antero-posterior motor unit distribution in the rat gluteus maximus muscle. We also provide evidence for a further axis of intracolumnar organization. The motor pools of the rat intercostal muscles, whose axons lie in a single, segmental nerve, have a ventro-dorsal axis in the ventral horn on which is mapped the proximo-distal position of the motor units. This suggests that during development, not only are motoneurons specified to innervate a particular muscle, but project within that muscle to a predictable location according to their position in the motoneuron pool. The presence of such topographical maps suggests that motoneurons are subject to greater developmental constraints than previously thought.
Animals↗
Postnatal growth of motor nerve terminals in muscles of the mouse.
A reduced silver stain was used to examine the development of complexity of motor nerve terminals in the postnatal period. Terminals in three histochemically different muscles were examined in mice aged 12 days to 3 years. The total number and total length of intraterminal axon branches increases with age, but only until animals are 3 months old. Terminals become longest and most branched in the histochemically glycolytic tensor fascia latae (TFL) muscle, shortest and least branched in the oxidative diaphragm, and intermediate in the histochemically mixed gluteus muscle. In addition, myelinated terminal branches develop in TFL and to a lesser extent in the gluteus between 1 and 3 months of age. These myelinated branches appear to be produced by nodal sprouting from the penultimate node of Ranvier of the terminal axon, and also by myelination of pre-existing terminal branches. The diameter of muscle fibres also increases until animals are 3 months old, and there is a good correlation between mean fibre diameter and either mean terminal length or mean number of terminal branches when all muscles at all ages are compared. This suggests that terminal growth could be determined by muscle fibre growth; however, within any given muscle there is little or no correlation between the diameter of a muscle fibre and either the length or number of branches of its nerve terminal, suggesting that terminal morphology is not controlled solely by muscle fibre growth. The presence of a myelinated branch in a nerve terminal is also unrelated to fibre diameter within a given muscle, but again when means are compared there are good, but significantly different correlations for the three different muscles. Thus some kind of muscle or nerve type-specific property additional to a general effect of muscle fibre size influences the development of myelinated terminal branches. Between 3 and 12 months of age terminal complexity remains constant or may decrease slightly. At 19 months or older, when mice are becoming senile, a large proportion of synapses have terminal sprouts and muscle fibres become innervated by two or more distinct axons. These changes can be attributed to the death of some motor neurons and sprouting of the remaining axons.
Aging↗