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Biomedical subjects

I Glass

Publications and source records attributed to I Glass.

At least 19 recordsLinked to original sources
PubMed2000

The short stature homeobox gene SHOX is involved in skeletal abnormalities in Turner syndrome.

Turner syndrome is characterized by short stature and is frequently associated with a variable spectrum of somatic features including ovarian failure, heart and renal abnormalities, micrognathia, cubitus valgus, high-arched palate, short metacarpals and Madelung deformity. Madelung deformity is also a key feature of Leri-Weill syndrome. Defects of the pseudoautosomal homeobox gene SHOX were previously shown to lead to short stature and Leri-Weill syndrome, and haploinsufficiency of SHOX was implicated to cause the short stature phenotype in Turner syndrome. Despite exhaustive searches, no direct murine orthologue of SHOX is evident. SHOX is, however, closely related to the SHOX2 homeobox gene on 3q, which has a murine counterpart, Og12x. We analysed SHOX and SHOX2 expression during human embryonic development, and referenced the expression patterns against those of Og12x. The SHOX expression pattern in the limb and first and second pharyngeal arches not only explains SHOX -related short stature phenotypes, but also for the first time provides evidence for the involvement of this gene in the development of additional Turner stigmata. This is strongly supported by the presence of Turner-characteristic dysmorphic skeletal features in patients with SHOX nonsense mutations.

Adult↗
PubMed2000

New insights into the genetic basis of intellectual disabilities.

BACKGROUND: Within general practice patients with intellectual disabilities are common. OBJECTIVE: This article sheds some new light on the underlying genetic mechanisms of intellectual disabilities. It outlines the genetic basis of known inherited and sporadic causes that have recently been understood through new molecular advances. DISCUSSION: General practice has an important role to play in pursuing a precise biomedical diagnosis by improving information provided to the patient and family regarding recurrence risks and prognoses as well as management issues specific to the underlying condition. New molecular techniques are providing us with specific diagnostic tools as well as improving our understanding of the complex mechanisms that contribute to what is known as human intelligence.

Child↗
PubMed1998

Mapping "cognitive" event-related potentials in prolonged postcoma unawareness state.

"Cognitive" auditory event-related potentials (ERPs) were mapped to examine the putative conscious responsiveness of eight patients in a postcoma unawareness (PCU) state and of eight matched normal controls. A "passive P3" paradigm was used to evaluate waves N2, P3, and Slow Waves of the ERPs. Results showed that the signal/noise ratio of the patients' waveshapes was poorer than that of the controls. Yet, on the whole, no between-group significant differences were noted for most of the averaged characteristics of the waves. In general, in the patients, the left hemisphere was dominated by negative potentials relative to the right one, whereas in the controls, the opposite asymmetry was apparent. Thirty-eight percent of the patients had passive N2 and P3 waves, and 67% of the responders regained consciousness (versus none of the non-responders). These findings suggest that the presence of intact "cognitive" waves is compatible with a higher probability for improvement, although nondetection of certain waves at the postcoma unawareness state does not necessarily indicate the worst prognosis.

Adolescent↗
PubMed1995

Median nerve conduction tests and Phalen's sign in carpal tunnel syndrome.

Carpal tunnel syndrome (CTS) is associated with sensory and/or motor dysfunction of the hand's fingers. The syndrome is caused by a continuous or intermittent pressure on the median nerve (NM) at the patient's wrist. 82 patients suffering from recent CTS symptoms, and 24 matched asymptomatic controls were tested. In the present study we examined five electrophysiological parameters and their correlations with a most commonly used clinical test--the Phalen test. The Phalen measure is the time from initial provocation until positive sign. The electrophysiological measurements are: NM Onset Sensory Velocity, NM Peak Sensory Velocity, NM Motor Nerve Velocity, NM Distal Motor Velocity, NM Residual Latency. Most of the symptomatic hands exhibited pathological values of their clinical or electrophysiological parameters. Phalen and Residual Latency were the most sensitive parameters. Phalen times were not significantly correlated with any of the five electrophysiological parameters, yet sensory velocity tended to decrease in patients with pathological Phalen values.

Adult↗
PubMed1993

Direct diagnosis of myotonic dystrophy with a disease-specific DNA marker.

BACKGROUND: Myotonic dystrophy is the most common inherited form of muscular dystrophy affecting adults. Its symptoms are not confined to muscle, and variability in their nature and in the patient's age at their onset can make diagnosis difficult. A specific unstable DNA sequence associated with myotonic dystrophy has recently been identified. We describe the use of a DNA probe (p5B1.4) that can detect this mutation directly, improving the accuracy and speed of diagnosis. METHODS: We analyzed DNA extracted from the peripheral-blood lymphocytes of 112 unrelated patients with myotonic dystrophy and their families, using molecular genetic techniques. Southern blot analysis and amplification with the polymerase chain reaction were used to determine the extent of expansion of the unstable DNA sequence. RESULTS: Probe p5B1.4 allowed direct identification of the myotonic dystrophy mutation in 108 of the 112 unrelated patients. In three families for whom the clinical and genetic data obtained with linked probes were ambiguous, the probe identified persons at risk for symptoms of this disorder and demonstrated that a possible sporadic case of myotonic dystrophy was familial. In one of these families the size of the unstable myotonic dystrophy-specific fragment decreased on transmission to offspring, who remained asymptomatic. CONCLUSIONS: The diagnosis of myotonic dystrophy is improved by the use of a probe that detects directly the mutation responsible for this disorder.

Adolescent↗
PubMed1990

A trial of family therapy versus a relatives' group for schizophrenia. Two-year follow-up.

The results are reported of a two-year follow-up of a trial of family sessions in the home (including patients) (12 families) versus a relatives' group (excluding patients) (11 families). Subjects were patients with schizophrenia living in high face-to-face contact with high-EE relatives. Patients were maintained on neuroleptic drugs for two years where possible. Relatives' critical comments and hostility were significantly lowered by nine months, but no significant changes occurred subsequently. Relatives' overinvolvement reduced steadily throughout the trial, and reduction in relatives' EE, either alone or in combination with reduced face-to-face contact, appeared to be associated with a lower relapse rate. The relapse rates for patients in the family-therapy and relatives'-group streams were 33% and 36% at two years. When these data were combined with the results of a previous trial, it was found that patients in families assigned to any form of social intervention had a two-year relapse rate of 40%, significantly lower than the 75% relapse rate for patients whose families were offered no help. We therefore recommend that relatives' groups are established in conjunction with some family sessions in the home for patients at high risk of relapse.

Communication↗
PubMed1989

Saccadic tracking of a periodic target motion in the cat.

Cats were tested for their ability to follow a dot target which periodically jumps horizontally from side to side. They can learn to perform saccadic tracking of various stimulus frequencies, and often they produce saccades predicting the target displacements. The preferred stimulus frequency for response to synchronize was in the 0.5-Hz range. Cats tend to undershoot the target. They also tend to adopt a strategy of locking predominantly to one direction of displacement, but they can be trained to reverse this preferred side or to lock to both sides. Saccades to the preferred side are more accurate, and longer and slower in comparison to saccades to the other side, thus demonstrating a velocity-accuracy trade-off phenomenon in the cat responses. Saccadic characteristics as expressed by the main sequence are apparently a stable property independent of the stimulus frequency.

Acceleration↗
PubMed1989

A trial of family therapy v. a relatives group for schizophrenia.

Schizophrenic patients living in high contact with relatives having high expressed emotion (EE) were recruited for a trial of social interventions. The patients were maintained on neuroleptic medication, while their families were randomly assigned to education plus family therapy or education plus a relatives group. Eleven out of 12 families accepted family therapy in the home, whereas only six out of 11 families were compliant with the relatives group. Non-compliance was associated with a poorer outcome for the patients in terms of the relapse rate. The relapse rate over nine months in the family therapy stream was 8%, while that in compliant families in the relatives group stream was 17%. Patients' social functioning showed small, non-significant, gains. The data from the current trial were compared with data from a previous trial. The lowering of the relapse rate in schizophrenia appears to be mediated by reductions in relatives' EE and/or face-to-face contact, and is not explained by better compliance with medication. Reduction in EE and/or contact was associated with a minuscule relapse rate (5%). Very little change occurred in families who were non-compliant with the relatives group. On the basis of these findings, we recommend that the most cost-effective procedure is to establish relatives groups in conjunction with family education and one or more initial family therapy sessions in the home. It is particularly important to offer home visits to families who are unable to or refuse to attend the relatives groups.

Adolescent↗
PubMed1987

Rethinking drug policies in the context of the acquired immunodeficiency syndrome.

This article presents a policy analysis of the needed responses to the problems associated with the acquired immunodeficiency syndrome and drug misuse that are now being experienced in the United Kingdom of Great Britain and Northern Ireland. Among the issues considered is the overall organizational and administrative capacity of a country to deal with a new acute demand and the probable need for more national centralization of planning and effort in the drug field. Policies must aim at small multiple gains rather than at master-strokes. International communication must be strengthened. The human immunodeficiency virus (HIV) epidemic requires re-examination of the penal handling of drug misusers. Treating more patients earlier may contribute significantly to prevention strategies, and methods for "harm reduction" deserve attention. Compulsory treatment or testing of HIV infection is not favoured. The importance of professional training and of research is stressed. Although the immediate focus is on one particular country's policy needs, the issues raised are of wider relevance.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Responses of cochlear nucleus units to electrical stimulation through a cochlear prosthesis: channel interaction.

The responses of 39 single units in the ventral cochlear nucleus of acute anesthetized guinea-pigs were studied with continuous electrical stimuli presented through a dual-channel implant in the scala tympani. Implants had four electrodes placed along the axis of the cochlea with 1 mm separations. With a specific pair (either apical or basal) of stimulating electrodes, about half of the units responded when current was flowing apically, while the rest responded to current in the opposite direction. No obvious relation existed between the effective polarity of the basal and apical pairs of electrodes. Two response types were observed while stimulating through both pairs simultaneously. Seventy-nine percent of the units responded to the sum of the current waveforms presented through the two pairs. Twenty-one percent responded to the difference between the waveforms. Both types of responses were observed for suprathreshold as well as for some intensities of stimulation that alone were subthreshold. The type of response was not dependent on the absolute threshold or threshold difference between the two pairs. For equal peak-intensities of stimuli, two-channel stimulation evoked larger responses than single-channel stimulation, provided the two channels were in their effective polarities. Responses to dual-channel stimulation were consistently larger than the summed responses to the two individual single-channel stimuli. The observed responses to the dual-channel stimulation indicate that the adequate stimulus was determined by the linear combination of fields produced by the individual channels in the vicinity of the stimulating electrodes before the auditory nerve is stimulated, and that excitation takes place in a spatially restricted area of the auditory nerve.

Animals↗
PubMed1984

Unit responses at cochlear nucleus to electrical stimulation through a cochlear prosthesis.

Afferent auditory fibers of the guinea pig cochlea were electrically stimulated with current introduced through electrodes in the scala tympani. Thresholds were determined for unit responses recorded in the ventral cochlear nuclei to a sinusoid of 98 Hz from response-rate growth functions versus stimulus intensity. Suprathreshold response rates for most units grew rapidly from threshold to saturation at 2-15 dB above threshold. Peristimulus time histograms were collected for responses to single sinusoids and combinations of two and five sinusoids ranging from 86 to 134 Hz. Spike occurrences were highly synchronous with individual cycles of the pure sinusoids, but responses to the more complex waveforms occurred primarily to the more intense peaks. The amplitude envelope was thus a major contributor to responses to multiple sinusoids. Destruction of cochlear structures with neomycin increased unit thresholds and produced some changes in waveform encoding.

Action Potentials↗
PubMed1983

Tuning characteristics of cochlear nucleus units in response to electrical stimulation of the cochlea.

The responses of single units in the ventral cochlear nucleus of acute anesthetized guinea pigs were studied with continuous sinusoidal electrical stimuli presented through a multi-electrode implant in the scala tympani. Implants had two or four electrodes along the axis of the scala with 1 mm separations. Best frequencies were consistently in the 100 Hz range (50-250 Hz) with thresholds of about 0.063 mA peak-to-peak. Tuning curves were usually symmetrical with slopes of 3-4 dB/octave, both below and above the best frequency. The relative sharpness of the tuning curves, as measured by Q10dB, averaged 0.2. Dynamic ranges as determined by the intensity-rate functions for the various frequencies were 2-15 dB. No significant difference was found between tuning characteristics of units in response to stimulation via the apical or basal pair of implant electrodes. The findings suggest some limitations on the applicability of independent stimulating channels in multi-electrode implants.

Acoustic Stimulation↗
PubMed1983

Responses of cells in the auditory cortex of awake squirrel monkeys to normal and reversed species-specific vocalizations.

Natural vocalizations and their artificial counterparts were found to be equally effective in evoking responses in auditory cortex units of awake squirrel monkeys. Neural responsiveness was presumably based primarily on the sensitivity of the units to acoustic transients embedded in the stimuli. For the left hemisphere, a significantly higher percentage of responding units was found in the primary compared to the secondary auditory cortex. However, the difference in the percentage of responding units between the primary and secondary auditory cortices was not significant for the right hemisphere.

Animals↗
PubMed1983

Auditory cortex responses to sequences of normal and reversed squirrel monkey vocalizations.

Responsiveness of auditory cortex (AC) units of awake squirrel monkeys to a natural sequence of species-specific calls was not significantly different from their responsiveness to a reverse playback of the sequence. No dependency was noted between the percentage of responding units and the average intensity of sounds, their spectral content or their order of presentation. The effectiveness of the sounds in eliciting responses was variable even when the sequence was produced in an unchanging behavioral context. Comparison of these findings with earlier results of individual vocalizations presented normally or backward in an isolated manner suggest that responsiveness of AC neurons to continuous sounds is lower than their responsiveness to isolated sounds, whether natural or artificial.

Animals↗