Search PubMed⌕ Search

Biomedical subjects

M Gross

Publications and source records attributed to M Gross.

At least 235 records · Page 13Linked to original sources
PubMed1997

[Hearing tests in extended high frequency range in pre-school age children. Initial results].

Since reliable headphones are now available, clinical audiometry can also be performed in extended high frequencies (EHF). Hearing in frequencies over 10 kHz is more influenced by age, noise and toxicity. Thus it is useful to take additionally results in children to establish the normal hearing threshold. In the present study, 35 pre-school children (ages 4-7 years) were tested by EHF (8 kHz-16 kHz) using a new Sennheiser HDA-200 headphone. The hearing thresholds recorded corresponded to those of other studied. Median and standard deviations for 10 kHz were 25 dB(SPL) +/- 12 dB(SPL), 35 dB(SPL) +/- 12 dB(SPL) for 12.5 kHz and 50 dB(SPL) +/- 15 dB(SPL) for 16 kHz. In the older children (> 5 years), hearing thresholds could be more reliably determined and were 10 dB(SPL) better than in the younger children (< 5 years). Thresholds at 10 kHz-12.5 kHz corresponded to those found in adults, but were more sensitive by 5 dB(SPL)-15 dB(SPL) in the 14 kHz-16 kHz range.

Adult↗
PubMed1997

[Dysarthric movement disorders of the velopharynx].

In this study we developed another method for the detection of nasopharyngeal closing patterns. This investigation of dynamic closure patterns was based on flexible video-nasopharyngoscopy and was undertaken in both healthy subjects and patients with dysarthria. Quantitative assessments of pharyngeal wall excursions allowed evaluation of closure patterns which were then matched with a predefined, mathematically-based algorithm. The results showed that a greater velopharyngeal constriction was maintained in the following order: resonants, open vowels, forced expiration, closed vowels, consonants, and swallowing. Variations in phonetic expressions of phonemes mainly interfered with velum excursion, whereas the lateral pharyngeal mucosal wall was minimally involved and the posterior wall portions were unaffected. Velopharyngeal closure patterns varied with different tasks: the velum was mainly moved for phonetic parameters, while lateral and posterior pharyngeal wall motion was observed on a large scale for swallowing. Comparison of subject groups revealed that patients with dysarthrias had reduced velar motility, leading to a more frequent hypernasal sound. Here, lateral pharyngeal walls showed a variable motility that in some cases was even more than in healthy subjects. Both groups exhibited qualitatively comparable velopharyngeal closure patterns, but significant differences were proved in their distributions.

Adult↗
PubMed1997

Myoadenylate deaminase deficiency, hypertrophic cardiomyopathy and gigantism syndrome.

We report a 20-year-old man with gigantism syndrome, hypertrophic cardiomyopathy, muscle weakness, exercise intolerance, and severe psychomotor retardation since childhood. Histochemical and biochemical analysis of skeletal muscle biopsy revealed myoadenylate deaminase deficiency; molecular genetic analysis confirmed the diagnosis of primary (inherited) myoadenylate deaminase deficiency. Plasma, urine, and muscle carnitine concentrations were reduced. L-Carnitine treatment led to gradual improvement in exercise tolerance and cognitive performance; plasma and tissue carnitine levels returned to normal, and echocardiographic evidence of left ventricular hypertrophy disappeared. The combination of inherited myoadenylate deaminase deficiency, gigantism syndrome and carnitine deficiency has not previously been described.

AMP Deaminase↗
PubMed1997

How the brain processes complex words: an event-related potential study of German verb inflections.

Event-related brain potentials (ERPs) were recorded as German-speaking subjects read verbs in correct and incorrect participle forms. The critical words were presented in three different versions to three different groups of subjects, as part of a simple sentence, in a word list, and embedded in a story; for each version separate ERPs were recorded. Three types of verbs were investigated, regulars, irregulars and nonce verbs. We compared correct regular and irregular participles with incorrect ones; the latter had -(e)n on verbs that actually take -t participles (* getanz-en), or -(e)t on verbs that require -(e)n (* gelad-et). For the nonce verbs, we compared participles with the unexpected -(e)n ending with the expected -t participle forms. The ERP responses were very consistent across the three versions of the experiment: (i) incorrect irregular participles (* gelad-et) elicited a left frontotemporal negativity; (ii) incorrect regulars (* getanz-en) produced no differences to the correct ones; (iii) nonce verbs were associated with an N400 component but did not show a difference between expected and unexpected endings. We will interpret these findings with respect to psycholinguistic models of morphological processing and argue that the brain processes regularly inflected words differently from irregularly inflected ones, the latter by accessing full-form entries stored in memory and the former by a computational process that decomposes complex words into stems and affixes.

Adult↗
PubMed1997

Structural and mechanistic consequences of polypeptide binding by GroEL.

The remarkable ability of the chaperonin GroEL to recognise a diverse range of non-native states of proteins constitutes one of the most fascinating molecular recognition events in protein chemistry. Recent structural studies have revealed a possible model for substrate binding by GroEL and a high-resolution image of the GroEL-GroES folding machinery has provided important new insights into our understanding of the mechanism of action of this chaperonin. Studies with a variety of model substrates reveal that the binding of substrate proteins to GroEL is not just a passive event, but can result in significant changes in the structure and stability of the bound polypeptide. The potential impact of this on the mechanism of chaperonin-assisted folding is not fully understood, but provides exciting scope for further experiment.

Amino Acid Sequence↗
PubMed1997

Clinical heterogeneity and molecular mechanisms in inborn muscle AMP deaminase deficiency.

Lack of the muscle-specific isoform of AMP deaminase (myoadenylate deaminase deficiency) can cause a metabolic myopathy, with exercise-induced muscle symptoms such as early fatigue, cramps and/or myalgia. It is the most common muscle enzyme defect in man, found in about 2-3% of all muscle biopsies. The genetic basis of the inherited defect is the nonsense mutation C34-T in the AMPD1 gene encoding myoadenylate deaminase. The mutation results in a premature stop of the enzyme synthesis. In a healthy German population, the frequency of the mutant allele was 0.1, and 1% of this population is expected to be homozygous for the mutation. In people with muscle symptoms, the allele frequency was significantly higher (0.145). The correlation between allele frequency and muscle symptoms underscores the clinical significance of this defect. However, the vast majority of homozygous subjects do not develop a metabolic myopathy. This clinical heterogeneity may be due to molecular genetic factors such as alternative splicing of the exon harbouring the mutation, or due to metabolic conditions such as pathways compensating for the defect. The real basis for the high percentage of asymptomatic homozygous subjects remains to be revealed.

AMP Deaminase↗
PubMed1997

The coronoid process as a cause of mandibular hypomobility--case reports.

In an attempt to draw the clinician's attention to the coronoid process site while evaluating the aetiology of the restriction of mandibular opening, four cases are illustrated. These cases represent a diversity of causes hampering the free rotational movement of the coronoid process in space during jaw function. Case 1 is an example of unilateral hyperplastic coronoid process and osteochondroma; case 2 shows unusually shaped short and divergent coronoid processes combined with a bucally displaced maxillary third molar on one side; cases 3 and 4 represent an anatomical variation of an extremely narrow vestibular space due to the close proximity of the medial aspect of the coronoid process to the distal molar. It is suggested that each clinical examination include the width of the buccal vestibular space while performing mandibular movements.

Adult↗
PubMed1997

Splinting osseointegrated implants and natural teeth in rehabilitation of partially edentulous patients. Part I: laboratory and clinical studies.

A significant clinical consideration in the restoration of partial edentulism with implant and tooth-supported prostheses is whether implants and natural teeth abutments should be splinted, and if so, in what manner. This article presents a review of laboratory and clinical studies related to splinting. Stress analysis studies reveal high stress concentration around the implant neck when rigidly connected to teeth. This was not borne out in in vivo studies in short-span bridges. While stress absorbing elements have been advocated to redistribute and reduce stress concentration away from the implant neck where bone resorption is often seen, finite element analysis and photo-elastic studies demonstrate that such stress absorbing elements may be effective only when their resiliency is in the same order of magnitude as the periodontal ligament. Clinical studies reporting life table statistics in combined implant and tooth restorations do not show adverse effects of splinting teeth to implants. These studies, however, are mostly short-term reports on survival with results that are as yet inconclusive. The issue of connecting with rigid or non-rigid connectors remains unresolved with a growing body of information favouring retrievable short-span rigid connection to non-mobile teeth. Root intrusion is a potential clinical hazard of non-rigid connection.

Bone Resorption↗
PubMed1997

Photophobia and phonophobia in migraineurs between attacks.

This study investigated whether migraineurs are more sensitive to light and sound while headache-free than are healthy people. Fifty-two migraineurs (mean age 39 years) were selected using the International Headache Society diagnostic criteria for migraine. Forty-eight healthy controls were matched for age, sex, and race (mean age 36 years). Visual and auditory discomfort thresholds were measured by exposing subjects to increasing light and sound until they complained of discomfort. There were significant differences between groups in both the light discomfort threshold (P < 0.00005) and the hearing discomfort threshold (P < 0.0005). The thresholds for both were lower in the migraineurs. Overall, for both groups together, there was a significant negative correlation between light discomfort threshold and age (correlation coefficient -0.2276, P = 0.011), but not for the hearing discomfort threshold and age (P = 0.275). The results show that the migraineurs were significantly more sensitive to light and sound when headache-free than were healthy controls. The apparent increased intolerance to light in both groups together noted with increased age, did not apply to the migraine group.

Adult↗
PubMed1997

[Spontaneous hematocornea after keratitis of various etiology].

BACKGROUND: Corneal blood staining may occur as a serious complication of persisting hyphema. In our two cases the corneal blood staining is a result of direct bleeding in the corneal stroma. HISTORY AND SIGNS: A female patient presented with a corneal blood staining through rupture of reopened vessels in interstitial keratitis of congenital syphilis after physical effort with high blood pressure. The second patient presented with a blood staining caused by a vessel errosion after corneal ulceration. THERAPY AND OUTCOME: The clearing of the blood staining is thought to be a result of the phagocytic action of the keratocytes and from a diffusion of hemoglobin into the conjunctival circulation and the anterior chamber (2). The therapeutic efforts are directed toward prevention of corneal blood staining. At the first sign of microscopic blood staining of the cornea a surgical evacuation of hyphema is necessary. In our two cases there wasn't a hyphema, so it was only possible to treated the corneal ulcer, entropion and systemic hypertension. CONCLUSION: The clinician has to wait for a spontaneous clearing, although it may take 2 or 3 years or more. In this case a penetrating keratoplasty is indicated.

Aged↗
PubMed1997

Medical prophylaxis of haemorrhage from oesophageal varices in patients with liver cirrhosis.

Haemorrhage from oesophageal varices is a life-threatening event in patients with liver cirrhosis. About 40-80% of patients surviving the first bleeding suffer a recurrence within 1 year. This high recurrence rate substantially contributes to the mortality in patients with liver cirrhosis. Therefore, various treatment regimens in both primary and secondary prophylaxis were studied. Most experience in medical primary prophylaxis was collected with beta-blockers, mainly propranolol. Treating patients with oesophageal varices with propranolol significantly reduces the incidence of first variceal bleeding. However, the effect on mortality is marginal, and primary prophylaxis is generally not recommended in these patients. Several studies support the hypothesis that medical prophylaxis with beta-blockers is more effective in reducing the rate of first oesophageal bleeding in patients with a high risk of haemorrhage, such as those with very large varices with red spots. A score to assess an individual patient's risk of variceal bleeding would be helpful, but until such a score has been validated, no general rule for this treatment decision can be given. In secondary prophylaxis, both beta-blockers and endoscopic therapy (sclerotherapy or ligation of the varices) are effective in lowering the rate of rebleeding. However, the effect on mortality was not significant in most studies. Several studies comparing the efficacy of medical prophylaxis and endoscopic treatment showed advantages of the endoscopic therapy with a greater reduction in recurrent bleeding episodes. However, medical prophylaxis with beta-blockers has the important advantage of being immediately effective, whereas endoscopic procedures provide the best protection against recurrent bleeding after complete obliteration of the varices. Therefore, in the first weeks and months of endoscopic therapy, additional treatment with beta-blockers may further reduce the risk of rebleeding. Only half of all studies on this topic reported a significant advantage with this combined therapy. Therefore, it seems reasonable to restrict this approach to patients with a high risk of rebleeding, such as patients with large sclerotherapy-derived oesophageal ulcers.

Adrenergic beta-Antagonists↗
PubMed1997

Neuropsychology of thallium poisoning.

Cases of thallium poisoning are rare and neuropsychological assessment has only been reported in detail in one other case. In the case reported here, neuropsychological assessments were carried out three, 12, and 54 months after diagnosis of thallium poisoning in a man who had acutely shown a number of neurological signs including confusion and disorientation and generalised slowing of EEG which was more prominent on the left. Evidence suggested that he had been exposed to thallium over a period of weeks. Neuropsychological assessment indicated an unexpected weakness in verbal abilities which persisted. This finding is consistent with the only other published case report which details neuropsychological effects after a single large dose of thallium and which also found a lateralised impairment.

Adult↗
PubMed1997

The cement mantle in femoral impaction allografting. A comparison of three systems from four centres.

An analysis of the cement mantle obtained with the Exeter impaction allografting system at one centre showed that it was either deficient or absent in almost 47% of Gruen zones. We therefore examined the mantle obtained using this system at another hospital and compared the results with those from the CPT and Harris Precoat Systems at other centres. The surgical indications for the procedure and the patient details were broadly similar in all four hospitals. There was some variation in the frequency of use of cortical strut allografts, cerclage wires and wire mesh to supplement the impaction allograft. Analysis of the cement mantles showed that when uncertain Gruen zones were excluded, the incidence of zones with areas of absence or deficiency of the cement was 47% and 50%, respectively, for the two centres using the Exeter system, 21% for the CPT system and 18% for the Harris Precoat system. We measured the difference in size between the proximal allograft impactors and the definitive prosthesis for each system. The Exeter system impactors are shorter than the definitive prosthesis and taper sharply so that the cavity created is inadequate, especially distally. The CPT proximal impactors are considerably longer than the definitive prosthesis and are designed to give a mantle of approximately 2 mm medially and laterally and 1.5 mm anteriorly and posteriorly. The Harris Precoat proximal impactors allow for a mantle with a circumference of 0.75 mm in the smaller sizes and 1 mm in the larger. Many reports link the longevity of a cemented implant to the adequacy of the cement mantle. For this reason, femoral impaction systems require careful design to achieve a cement mantle which is uninterrupted in its length and adequate in its thickness. Our results suggest that some current systems require modification.

Acetabulum↗
PubMed1997

Rehabilitation in Franceschetti syndrome: an interdisciplinary approach using bone-anchored hearing aids.

The purpose of the study was to determine the effectiveness of a concept of combined interdisciplinary rehabilitation for children with mandibulofacial dysostosis, developed at the Center for Facial Malformations. It consists of binaural implantation of bone-anchored hearing aids and gradual distraction of the mandible. After audiological testing and mandibular distraction on a phantom head designed with data from a spiral CT, the surgery was done in three steps: implanting the fixtures for BAHA and the bone-lengthening device, removing the device after six weeks and completing the BAHA implantation two months later. The distraction procedure and orthodontic treatment were performed on an outpatient basis. The results (six patients, ages 6-19 years) were excellent: after implantation of the BAHA system speech perception increased from approximately 85% with the conventional BCHA to 95-100% with the BAHA. Quality of life was reported to be much better because of the general cosmetic improvement as well as the good acoustic orientation and sound quality with the new hearing devices. We conclude that the interdisciplinary approach provides favorable conditions for rehabilitation in cases of complex malformations of the head and neck.

Abnormalities, Multiple↗
PubMed1997

The risk of developing lung cancer associated with antioxidants in the blood: ascorbic acid, carotenoids, alpha-tocopherol, selenium, and total peroxyl radical absorbing capacity.

Lung cancer cases diagnosed during the period 1975 through 1993 and matched controls were identified in the rosters of Washington County, Maryland residents who had donated blood for a serum bank in 1974 or 1989. Plasma from participants in the 1989 project was assayed for ascorbic acid; serum or plasma was assayed for participants in either project for alpha- and beta-carotene, cryptoxanthin, lutein/zeaxanthin, lycopene, alpha-tocopherol, selenium, and peroxyl radical absorption capacity. Among the total group of 258 cases and 515 controls, serum/plasma concentrations were significantly lower among cases than controls for cryptoxanthin, beta-carotene, and lutein/zeaxanthin with case-control differences of -25.5, -17.1, and -10.1%, respectively. Modest nonsignificant case-control differences in a protective direction were noted for alpha-carotene and ascorbic acid. There were only trivial differences for lycopene, alpha-tocopherol, selenium, and peroxyl radical absorption capacity. Findings are reported for males and females and for persons who had never smoked cigarettes, former smokers, and current smokers at baseline. These results and those from previous studies suggest that beta-carotene is a marker for some protective factor(s) against lung cancer; that cryptoxanthin, alpha-carotene, and ascorbic acid need to be investigated further as potentially protective factors or associates of a protective factor; and that lycopene, alpha-tocopherol, selenium, and peroxyl radical absorption capacity are unlikely to be associated with lung cancer risk. Until specific preventive factors are identified, the best protection against lung cancer is still the avoidance of airborne carcinogens, especially tobacco smoke; second best is the consumption of a diet rich in fruits and vegetables.

Adult↗