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Biomedical subjects

B Matthews

Publications and source records attributed to B Matthews.

At least 37 records · Page 2Linked to original sources
PubMed1999

Hernia at 5-mm laparoscopic port site presenting as early postoperative small bowel obstruction.

A decade has passed since laparoscopy became a popular tool in general surgery. New technologies continue to surface, and surgeons are still trying to expand the applications of this technique. Parallel to the development of new techniques, we are also measuring the presentation of new complications. Incisional hernias are not new complications. Although their avoidance has been one of the proposed benefits of laparoscopy, several cases of port-site hernias have been reported. Current surgical wisdom suggests closure of 10-mm or larger port sites to avoid herniation. Most surgeons do not routinely close 5-mm port sites, believing that such fascial defects are not large enough to create a significant risk of hernia formation, thus not justifying the extra time and effort needed to close them. Although this practice may be reasonable for most cases, it should be reconsidered in lengthy procedures, particularly if the port has been used for active operative instruments. Under these circumstances, the repetitive motions in different directions may cause the 5-mm defect to enlarge significantly, allowing a hernia of considerable size to develop, with the obvious clinical implications of such a complication. We present a case of a hernia through a 5-mm port site presenting as small-bowel obstruction in the early postoperative period after a laparoscopic paraesophageal hernia repair.

Aged↗
PubMed1999

Hip and ankle range of motion and hip muscle strength in young female ballet dancers and controls.

OBJECTIVES: To compare the hip and ankle range of motion and hip muscle strength in 8-11 year old novice female ballet dancers and controls. METHODS: Subjects were 77 dancers and 49 controls (mean (SD) age 9.6 (0.8) and 9.6 (0.7) years respectively). Supine right active hip external rotation (ER) and internal rotation (IR) were measured using an inclinometer. A turnout protractor was used to assess standing active turnout range. The measure of ER achieved from below the hip during turnout (non-hip ER) was calculated by subtracting hip ER range from turnout range, and hip ER:IR was derived by dividing ER range by IR range. Range of right weight bearing ankle dorsiflexion was measured in a standing lunge using two methods: the distance from the foot to the wall (in centimetres) and the angle of the shank to the vertical via an inclinometer (in degrees). Right calf muscle range was measured in weight bearing using an inclinometer. A manual muscle tester was used to assess right isometric hip flexor, internal rotator, external rotator, abductor, and adductor strength. RESULTS: Dancers had less ER (p<0.05) and IR (p<0.01) range than controls but greater ER:IR (p<0.01). Although there was no difference in turnout between groups, the dancers had greater non-hip ER. Dancers had greater range of ankle dorsiflexion than controls, measured in both centimetres (p<0.01) and degrees (p<0.05), but similar calf muscle range. After controlling for body weight, controls had stronger hip muscles than dancers except for hip abductor strength which was similar. Regression analyses disclosed a moderate relation between turnout and hip ER (r = 0.40). There were no significant correlations between range of motion and training years and weekly training hours. CONCLUSIONS: Longitudinal follow up will assist in determining whether or not hip and ankle range in young dancers is genetically fixed and unable to be improved with further balletic training.

Ankle Joint↗
PubMed1998

Distribution of P2X3 receptors in the rat trigeminal ganglion after inferior alveolar nerve injury.

The ATP-gated cation channel receptor P2X3 is associated with nociceptive primary sensory neurons. We have, using immunohistochemistry, examined the expression of P2X3 in rat trigeminal ganglia 4-22 days after ligation/section or chronic constriction of the mandibular inferior alveolar nerve. In the normal trigeminal ganglion the anti-P2X3 receptor antibody labeled 37-58% of all neurons. Double labeling demonstrated that about 70-95% of the small neurons that bind the isolectin I-B4 displayed P2X3-immunoreactivity, and that about 40% of larger RT97-positive nerve cells were P2X3 receptor-immunoreactive. At 4 and 10 days after inferior alveolar nerve injury, the proportion of P2X3-immunoreactive neurons had increased to about 65% (range 52-78%). Examinations at the injury sites showed an intense P2X3 receptor-immunoreactivity in nerve endings. At longer survival stages the proportion of P2X3 receptor-positive sensory neurons had returned to control values. These results show that the P2X3 receptor is transiently upregulated and anterogradely transported in trigeminal primary sensory neurons after nerve injury. Since the receptor is accumulated in injured nerve endings, it may be associated with abnormal impulse propagation from these sites.

Animals↗
PubMed1998

Establishment and evaluation of a preschool asthma programme: a pilot study.

In New Zealand asthma has been recognised as a major health issue for preschool children and their families (Public Health Commission, 1995). While nurses have been involved with Asthma Self management programmes which have improved the outcomes for older children and adults (Garret, Kolbe, Richards, Whitlock & Rea, 1995: Mitchell, Ferguson & Norwood, 1986) self management programmes have rarely been used for preschool children. The aims of the study were to establish a Preschool Asthma Programme and evaluate whether it would enable parents and their children to increase their knowledge, confidence and skills in asthma management, while improving asthma control. Fifteen families with children aged between three and a half and five years with moderate and severe asthma participated; five families in each of the three programmes offered. The programmes were evaluated using both formative and outcome evaluation. Results indicated that the programme increased knowledge and changes in asthma management by parents and children and increased the confidence of parents in both their own ability, and that of their child, to manage asthma. Seven parents and seven children on the programme achieved positive change in all the self management criteria considered and six parents and two children made changes in most of them. Participation in the programme was associated with improved lung function, asthma control and preschool attendance. The programme was more successful if the child was over four years old and had suboptimal asthma control. It is concluded that, contrary to what has previously been thought, preschool children can be taught self management skills. There is evidence that a Preschool Asthma Programme is a useful addition to the conventional management and can result in improvements in asthma management.

Adult↗
PubMed1998

A system for tracking dental readiness in the Air Force Reserve.

The potential of dental emergencies to reduce combat effectiveness is a major concern of military planners. The dental fitness classification is teh primary measure of an airman's dental readiness. A dental class 3 identification means that the airman has a dental condition that is likely to cause a dental emergency within 12 months. With few exceptions, Air Force Reserve command units are using only nonstandardized, manual tracking systems to ensure that identified members get needed dental treatment completed in a timely manner. The reliability and effectiveness of this process has been questioned in recent years. The importance of accurately recording the dental class status and having a reliable means to track dental treatment compliance of members designated dental class 3 is essential to maintaining a high state of dental readiness. A computerized tracking system called the Reserve Dental Data System was designed and developed to address this problem.

Aerospace Medicine↗
PubMed1997

FlyBase: a Drosophila database. The FlyBase consortium.

FlyBase is a database of genetic and molecular data concerning Drosophila. FlyBase is maintained as a relational database (in Sybase) and is made available as html documents and flat files. The scope of FlyBase includes: genes, alleles (and phenotypes), aberrations, transposons, pointers to sequence data, clones, stock lists, Drosophila workers and bibliographic references. The Encyclopedia of Drosophila is a joint effort between FlyBase and the Berkeley Drosophila Genome Project which integrates FlyBase data with those from the BDGP.

Animals↗
PubMed1996

Experiments in pigs on the sources of laser Doppler blood-flow signals recorded from teeth.

A laser Doppler blood-flow meter (Moor Type MBF3D) was used to record from the crowns of eight deciduous mandibular incisors in three anaesthetized pigs. The flow-meter probe was attached to the crown either 2 or 6 mm from the gingival margin. Recordings were made from each tooth with the supporting tissues intact, after exposing the root pulp, after cutting the pulp, and after death of the animal. At each stage the effect of wrapping the crown in aluminium foil was determined. There was no significant change in the signals when the root pulp was exposed (p > 0.05, paired t-test). Without foil, cutting the pulp reduced the signal recorded 2 mm from the gingival margin by an average of 85.1 percent (n = 8, p < 0.001) and at 6 mm by 87.9 percent (n = 4, p < 0.001). There were further significant reductions (p < 0.01) equivalent to 12.9 percent and 9.0 percent, respectively, of the control values when the animal was killed. The foil increased the average blood-flow signals recorded from intact teeth at both 2 and 6 mm from the gingival margin by 77.8 percent and 98.3 percent (p < 0.05), respectively. It also had a similar effect after pulp exposure. With foil, cutting the pulp reduced the signal by 86.2 percent and 92.8 percent at the two sites, respectively, and post mortem there was a further reduction of 12.4 percent and 6.1 percent. Thus, under all conditions the major part of the signal recorded from an intact tooth was from the pulp but a significant component (an average of between 14.9 percent and 7.2 percent depending on the conditions) was from tissues outside the tooth. The best performance was obtained with foil and with the probe 6 mm from the gingival margin.

Aluminum↗
PubMed1995

Microvascular architecture and exchange in teeth.

Dental pulp is a low-compliance tissue surrounded by an avascular hard tissue case. Resin casts of the microvasculature in teeth of limited growth show arterioles and venules arranged axially in the pulp with capillary loops extending out toward the dentine. The capillary density is high. There is ultrastructural evidence for lymphatics in pulp. Pulpal blood flow has been estimated in intact teeth using radiolabeled microspheres and found to be in the range 20-60 ml/min per 100 g tissue. One of the difficulties of studying this tissue is that a cavity has to be cut into the tooth with the inherent risks that this may affect the parameters under study. Measurements from exposed pulp indicate that the tissue fluid pressure is high and pulsatile. Furthermore, micropuncture studies have shown that the arteriolar pressure is lower and the venular pressure higher than in other tissues. When dentine is exposed in vivo, fluid moves out through the dentinal tubules and this appears to be formed by a process of ultrafiltration from the pulpal interstitial fluid. The flow is sufficient to retard significantly the diffusion of chemicals into dentine from the oral cavity.

Animals↗
PubMed1994

Interactions between neural and hydrodynamic mechanisms in dentine and pulp.

Evidence is presented that the rate of inward diffusion of chemicals through exposed dentine is affected by the rate of outward flow of fluid through the dentinal tubules. Such a flow has been demonstrated in cats. The flow rate appears to depend upon the pulpal tissue-fluid pressure; flow increased during pulp vasodilatation and decreased, even reversing in direction, during vasoconstriction. Pulp vasodilatation can be produced by stimulating intradental afferent nerves, including some of those that seem to be excited by displacement of tubule contents (i.e. by a hydrodynamic mechanism). Thus, when dentine is exposed and these afferents are stimulated they will help to protect the pulp by producing reflex vasodilatation, which will decrease the rate of diffusion of toxins from the mouth into the pulp. The relation between the rate of flow through dentine and the discharge evoked in intradental nerves was investigated in cats. Single fibres were more sensitive to outward than to inward flow. The flow rates required to excite the pulp afferents were greater than those observed during even maximal pulpal vasodilatation.

Animals↗
PubMed1993

Experiments on extracted teeth into the validity of using laser Doppler techniques for recording pulpal blood flow.

The performances of two laser Doppler flow meters (Periflux model PF3 and Moor Blood Flow Monitor model MBF3D) were investigated. Recordings were made while diluted blood was pumped at different rates through the pulp cavities of extracted human or pig teeth. The probe of each instrument was fixed to the enamel surface 2 mm from the original position of the gingival margin. Both instruments performed similarly, although the Moor gave the better signal/noise ratios. Both were capable of detecting flow in the core of the pulp as well as the superficial part closest to the probe tip. With either instrument, and with any one dilution of blood (range 0.5-45% v/v red cells), there was a near-linear relationship between the blood-flow signal and the flow rate of blood through the tooth. However, when data obtained with different red-cell concentrations were compared, a good correlation between the blood-flow signal and red-cell flux (product of concentration and mean velocity) was obtained only with red-cell concentrations up to 1% v/v. Therefore these instruments would give an accurate indication of blood flow changes only under conditions in which either this value was not exceeded or if the red-cell volume fraction remained constant; neither of which can be assumed to apply when recording from teeth in situ. The signals representing the concentration of moving blood cells were unreliable in both instruments. It is concluded that the information provided by these laser Doppler flow meters can be ambiguous and must be interpreted with care.

Adult↗
PubMed1993

A technique for recording the activity of brain-stem neurones in awake, unrestrained cats using microwires and an implantable micromanipulator.

A new technique is described which is suitable for long-term recording of the activity of neurones in the brain of an awake, unrestrained cat. By using telescopic electrodes, neurones up to 39 mm from the cranial surface can be reached with a miniature micromanipulator which is small enough to be left in place between recording sessions. The most stable recordings have been obtained with electrodes made from microwire, with which units have been held for up to 8 h.

Animals↗
PubMed1993

Some aspects of the use of laser Doppler flow meters for recording tissue blood flow.

Laser Doppler flow meters are used to provide continuous records of blood flow in tissues. An account is given of their principles of operation and of the differences between two of the commercially available instruments: the Periflux model PF3 and the Moor blood flow monitor model MBF3D. The Periflux tended to have higher noise levels and to drift more than the Moor. The principal disadvantage of these instruments is that they cannot be calibrated in absolute units of blood flow. It is suggested that the method of standardization adopted for the Periflux be used with other machines, based on the signal produced by the Brownian motion of a 0.5% suspension of 0.48 micron diameter polystyrene microspheres at 20 degrees C. The signal representing zero flow in a tissue can be obtained by recording with the same light intensity from a stationary reflector. In model systems the instruments are linear with red cell volume fractions up to only 1%, which is below that likely to be encountered in many tissues. The effects of ambient light and the origin of movement artifacts are also considered.

Blood Flow Velocity↗
PubMed1993

Responses of trigeminal brain stem neurons and the digastric muscle to tooth-pulp stimulation in awake cats.

1. Cats were prepared for chronic recording from neurons in pars oralis and pars interpolaris of the trigeminal spinal nucleus. Electrodes were implanted into canine teeth for electrical stimulation and the digastric muscle for recording electromyograms. 2. Recordings were made from the animals when they were awake and unrestrained as well as when they were lightly anesthetized. Some neurons were studied under both conditions. 3. In an awake animal, single tooth-pulp stimuli of 0.1 ms duration and < or = 1 mA intensity produced no aversive behavior. 4. The response of trigeminal brain stem neurons in the awake animal to such stimuli consisted of short (approximately 3 ms)- and long (approximately 25 ms)-latency discharges whose thresholds suggested that they were both due to inputs from fast conducting primary afferent fibers. 5. Light anesthesia reduced the number of impulses in both components and in most cases completely abolished the long-latency component evoked by low-intensity stimuli. The threshold of the short-latency component was little affected by light anesthesia. It is postulated that the short-latency component is mediated by a monosynaptic input from primary afferent fibers and the long-latency component by a polysynaptic input from these same fibers. 6. All neurons that responded to tooth-pulp stimulation had inputs from other orofacial sites both in the awake and lightly anesthetized states. After light anesthesia, these receptive fields were altered in only 3 out of 15 neurons. 7. The majority of neurons (18 out of 20) were not spontaneously active in the awake animal. Spontaneous activity in the other two was reduced by light anesthesia. 8. The threshold of the digastric reflex evoked by tooth-pulp stimulation was not altered by light anesthesia, but the size of the response was reduced. 9. The effects of changing the level of anesthesia from deep to light (i.e., without and with reflex withdrawal to squeezing a paw) on the responses to tooth-pulp stimulation were also studied. Decreasing the anesthetic depth tended to decrease the thresholds and increase the magnitude of both the short- and long-latency neuronal responses and the short-latency digastric response.

Afferent Pathways↗
PubMed1993

Compartment syndrome and shin splints of the lower leg.

OBJECTIVES: The objective of this article is to review and categorize the current knowledge on compartment syndromes (CS) and shin splints (SS), with specific importance relegated to the diagnosis, differential diagnosis and management of these conditions. DATA SOURCES: The bibliographic data sources reviewed are limited to the English language and human content and are from medical and scientific journals, as well as chiropractic and medical texts. A mini-Medline version of Index Medicus was utilized. Terms for indexing included compartment syndromes, shin splints and stress fractures. The bibliographies of the journals selected were then evaluated and, where appropriate, the specific journal or text references regarding diagnosis and management were then reviewed. This information was then included in this article, where useful, to further clarify or reference statements made. CONCLUSION: Differential diagnosis of the acute CS from chronic CS and SS requires clinical methods and imaging procedures. The pathogenesis of the acute CS of the lower leg is associated with external pressure or internal hemorrhage. If the tissue pressure were to rise above 30-40 mm Hg for 4-12 h, irreversible muscular damage would result. Emergency surgical intervention is the only appropriate form of treatment in acute CS. In chronic CS, where elevated pressures exist on a transient basis, influenced by activity, conservative management procedures are felt to be effective. However, if these methods are not helpful, surgical intervention may be necessary. The etiology of pain associated with SS is not associated with compartmental pressure elevations, but rather, results from periostitis occurring along the tibia caused by muscular and tendinous strain associated with inflammation. Conservative management is most appropriate for this disorder, with surgical intervention being an uncommon treatment approach. Although clinical findings are useful in the diagnosis of these disorders, fluid pressure findings may be necessary to fully differentiate acute CS from other disorders. Up until recently, common methods of obtaining pressure measurements of compartments included the use of a needle manometer. More recently, however, a hand-held miniature fluid pressure monitor has been developed that produces reproducible measurements of interstitial fluid, making testing potentially practical for the clinician.

Acute Disease↗
PubMed1992

Drosophila single-minded gene and the molecular genetics of CNS midline development.

Our goal is to understand the molecular mechanisms that govern the formation of the central nervous system. In particular, we have focused on the development of a small group of neurons and glia that lie along the midline of the Drosophila CNS. These midline cells possess a number of unique attributes which make them particularly amenable to molecular, cellular, and genetic examinations of nervous system formation and function. In addition, the midline cells exhibit distinctive ontogeny, morphology, anatomical position, and patterns of gene expression which suggest that they may provide unique functions to the developing CNS. The single-minded gene encodes a nuclear protein which is specifically expressed in the midline cells and has been shown to play a crucial role in midline cell development and CNS formation. Genetic experiments reveal that sim is required for the expression of many CNS midline genes which are thought to be involved in the proper differentiation of these cells. In order to identify additional genes which are expressed in some or all of the midline cells at different developmental stages, a technique known as enhancer trap screening was employed. This screen led to the identification of a large number of potential genes which exhibit various midline expression patterns and may be involved in discrete aspects of midline cell development. Further molecular, genetic, and biochemical analyses of sim and several of the enhancer trap lines are being pursued. This should permit elucidation of the genetic hierarchy which acts in the specification, differentiation, and function of these CNS midline cells.

Animals↗