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Biomedical subjects

J Helms

Publications and source records attributed to J Helms.

At least 37 records · Page 2Linked to original sources
PubMed1994

Human-papillomavirus DNA in cholesteatomas.

Cholesteatoma of the middle ear is a relatively common disorder, often with severe consequences. Histologically, the aggressively growing, bone-destructing form shows papillary growth and koilocytosis, which are characteristic of papillomavirus-induced lesions. A PCR (polymerase chain reaction) method using degenerate primers for the detection of any known or as yet unknown HPV (human papillomavirus) type was applied in screening 51 biopsies from 42 patients. A resulting 36% (16/45) of the cholesteatomas were found to contain papillomavirus DNA, which hybridized under stringent conditions with an HPV-II DNA probe. In 3 cases the presence of HPV-II DNA could be confirmed by sequencing the PCR products. The mere presence of this HPV DNA does not prove an etiological role of this group of viruses in the induction of cholesteatomas. It does, however, identify another group of human proliferative lesions putatively linked to papillomavirus infections.

Adolescent↗
PubMed1994

Closure of the petrous apex of the temporal bone with ionomeric cement following translabyrinthine removal of an acoustic neuroma.

When performing translabyrinthine surgery for acoustic neuroma, the surgeon opens the cerebrospinal fluid space. To prevent the development of post-operative meningitis, the surgical defect should be closed reliably in a watertight fashion. To date, this has been done with success in 12 patients altogether using a self-curing bone cement (ionomeric cement). During follow-up for a maximum of three years there has been no evidence of cerebrospinal fluid leaks.

Bone Cements↗
PubMed1994

[Restoration of sound transmission in the middle ear by reconstruction of the ossicular chain in its physiologic position. Results of incus reconstruction with ionomer cement].

We report the use of an ionomeric based bone substitute to reconstruct the ossicles in their normal position. To reconstruct small defects of the incudo-stapedial joint, this bone replacement material is applied to the long process of the incus and the head of the stapes. After setting and hardening a stable contact to the adjacent bone is formed. The audiological results after reconstruction of small incus defects with ionomeric cement are discussed in comparison to stapedectomy and tympanoplasty.

Adult↗
PubMed1994

Simultaneous measurement of cardiac output by thermodilution, thoracic electrical bioimpedance and Doppler ultrasound.

To evaluate the accuracy of two non-invasive techniques for cardiac output (CO) measurement, we have measured CO simultaneously by thoracic electrical bioimpedance (TEB), pulsed Doppler ultrasound (DU) and standard thermodilution methods (TD) under different clinical conditions. Measurements were made in 10 patients: (I) during steady state anaesthesia with controlled IPPV ventilation (n = 131), spread over the entire ventilatory cycle; (II) during apnoea (n = 56); (III) during spontaneous breathing (n = 152) in the intensive care unit. Mean (SD) cardiac output values were: (I) COTD 3.5 (1.0) litre min-1, COTEB 3.4 (0.7) litre min-1, CODU 2.8 (0.7) litre min-1; (II) COTD 3.6 (0.6) litre min-1, COTEB 3.5 (0.4) litre min-1, CODU 2.9 (0.7) litre min-1; (III) COTD 7.7 (1.5) litre min-1, COTEB 7.6 (1.9) litre min-1, CODU 5.2 (1.4) litre min-1. The mean percentage deviation of TEB from TD ranged from -2.2% to 1.4% and that of DU from TD was from -16% to -32%. There were no statistically significant differences between TD and TEB, but TD and DU differed significantly during IPPV, apnoea and spontaneous ventilation (P < 0.0001).

Adult↗
PubMed1994

Presentation and diagnosis of small acoustic tumors.

With the recent advent of magnetic resonance imaging and auditory brain stem response, it is now possible to diagnose acoustic tumors while they are still quite small. As a result, it is becoming obvious that the clinical presentation of these smaller lesions can be somewhat variant to what is considered typical for an acoustic neuroma. Likewise, although the sensitivity of auditory brain stem response for larger tumors is believed to be quite good, the sensitivity for smaller tumors has recently been questioned, particularly when the patient is first seen early in the course of the disease with only mild otologic complications. To assess auditory brain stem response results as well as clinical and audiologic presentations, we conducted a retrospective study of patients treated for small acoustic tumors (less than 1 cm). Of the 70 patients included in the study, auditory brain stem response was abnormal in 65 (93%), on the basis of wave V latency prolongation and interaural latency differences. This would indicate that auditory brain stem response is a valid screening test for acoustic tumors, even in early stages of development. The clinical presentation of patients with small acoustic tumors was similar to that reported for acoustic tumors in general, but with vertigo occurring more frequently in patients with smaller tumors. Several atypical patterns of hearing loss were also noted.

Adult↗
PubMed1994

Relationship between retinoic acid and sonic hedgehog, two polarizing signals in the chick wing bud.

Local application of all-trans-retinoic acid (RA) to the anterior margin of chick limb buds results in pattern duplications reminescent of those that develop after grafting cells from the zone of polarizing activity (ZPA). RA may act directly by conferring positional information to limb bud cells, or it may act indirectly by creating a polarizing region in the tissue distal to the RA source. Here we demonstrate that tissue distal to an RA-releasing bead acquires polarizing activity in a dose-dependent manner. Treatments with pharmacological (beads soaked in 330 micrograms/ml) and physiological (beads soaked in 10 micrograms/ml) doses of RA are equally capable of inducing digit pattern duplication. Additionally, both treatments induce sonic hedgehog (shh; also known as vertebrate hedgehog-1, vhh-1), a putative ZPA morphogen and Hoxd-11, a gene induced by the polarizing signal. However, tissue transplantation assays reveal that pharmacological, but not physiological, doses create a polarizing region. This differential response could be explained if physiological doses induced less shh than pharmacological doses. However, our in situ hybridization analyses demonstrate that both treatments result in similar amounts of mRNA encoding this candidate ZPA morphogen. We outline a model describing the apparently disparate effects of pharmacologic and physiological doses RA on limb bud tissue.

Animals↗
PubMed1994

[Auditory results after transtemporal removal of acoustic neurinoma].

A retrospective study was conducted to assess results of hearing in patients who underwent resections of acoustic neuromas via the middle fossa approach. A statistical correlation of results with preoperative clinical and audiological data determined if any prognostic indicators could be associated with successful preservation of hearing. Of 93 patients included in the study, useful hearing was preserved in 54 (58%), while hearing was preserved within 10 dB of preoperative levels in 42 patients (45%). The possibility for hearing preservation appeared to be inversely related to the size of the acoustic tumor, with hearing preserved in 39 of 65 patients (60%) with tumors less than or equal to 0.5 cm. Preoperative hearing levels and electronystagmography seemed to have no prognostic value. However, auditory brain stem responses showed that a wave V latency of less than 6.8 msec was associated with an increased chance of hearing preservation. Additionally, the presence of vertigo as a pre-operative complaint appeared to be a good prognostic indicator for successful hearing preservation.

Adult↗
PubMed1993

Ionomer-based bone substitute in otologic surgery.

During post-set hardening the self-curing bone substitute Ionocem develops a solid bond with the adjacent bony tissue, leaving no empty spaces. The fully matured material can be fixed to bone with freshly mixed cement or it may be used as a blank, e.g. an ossicular implant (Ionos ossicle). After insertion of 945 alloplastic middle ear prostheses over a period of 4.5 years, the take-rate was 94%. In some patients revision surgery became necessary, in 50% of cases because of prosthesis dislocation. A granular version of the cement (Ionogran) was implanted in 46 ears for obliteration of mastoid cavities and showed complete mucosal overgrowth within a maximal period of 3 months. Posterior canal wall reconstruction with the self-curing bone substitute was done in 74 patients, with revisions required in 12 cases because of persistent epithelial deficits in the external ear canal or epitympanic retraction. Overall results showed that the ionomer-based cement was a useful substitute for bone in reconstructive otologic surgery.

Animals↗
PubMed1993

[Ionomer cement in cochlear implant surgery].

Ionomer-based cement is a new bone replacement material. After promising results have been obtained with this material in middle ear and skull base surgery as well as in plastic reconstructive surgery, this material can be used to fix a cochlear implant system (internal receiver as well as the electrode) to the temporal bone. This material is formed via a reaction of a glass powder with a polycarboxylic acid. The cement has a manipulation period of about 5 minutes. After setting, the cement is well tolerated by tissue and has the additional advantage of being biocompatible and permanently stable in a biological environment. The cement and the acid are commercially available as a two-component capsulated system. In cochlear implant surgery this material is used to achieve a stable attachment of the internal receiver to the temporal bone. Displacement and damaging of the internal receiver and the electrode are prevented.

Cochlear Implants↗
PubMed1993

Cloning, sequencing, and molecular analysis of the sol operon of Clostridium acetobutylicum, a chromosomal locus involved in solventogenesis.

A DNA region of Clostridium acetobutylicum contiguous with the adc operon has been cloned and sequenced. Structural genes encoding the acetoacetyl coenzyme A:acetate/butyrate:coenzyme A transferase (ctfB and ctfA) and an alcohol/aldehyde dehydrogenase (adhE) could be identified. These three genes together with a small open reading frame (ORF) of unknown function (upstream of adhE) formed an operon (sol operon), as shown by mRNA analyses. The complete sol operon was transcriptionally induced or derepressed before the onset of solventogenesis, thus confirming earlier results of Northern hybridizations with a ctfB gene probe (U. Gerischer and P. Dürre, J. Bacteriol. 174:426-433, 1992). Upstream of the sol operon, we identified two putative promoters that were located in regions with possible stem-loop structures formed by several inverted repeats. The distal promoter P1 showed only minor transcription initiation in solventogenic C. acetobutylicum cells but was recognized in Escherichia coli, presumably because of its high similarity to the sigma 70 consensus sequence. The adhE-proximal promoter P2 directed the major transcription start point in solventogenic C. acetobutylicum but was not recognized in E. coli. The clostridial AdhE showed high similarity to a novel family (type III) of alcohol dehydrogenases. Two other ORFs (ORF 5 and ORF 6) were found on the cloned DNA region that showed no significant similarity to sequences in various available data bases. mRNA studies revealed that ORF 5 formed a monocistronic operon and showed increased expression before onset of solventogenesis.

Alcohol Dehydrogenase↗
PubMed1992

[Immunohistochemistry of the Scarpa's ganglion and the crista ampullaris of patients with Menière disease].

In certain long-lasting cases of Menière's disease with recurrent attacks, despite of saccotomy, the removal of the vestibular ganglion is the only procedure that relieves vertigo. During ganglionectomy of this group of patients all fresh tissues gotten and gathered from operation are frozen immediately and preserved for immunohistochemical assay with direct and indirect incubations. The positive findings such as ASMA+, AEA+ and ANA+ in tissues of patient's own as well as in control tissues further confirmed the results previously reported by us. The immune-complex mediated arteriolar and capillary vasculitis on the basis of an autoimmune disorder as a secondary autoimmune marker might play a dominant role in this patients group. The demyelination of vestibular neurons in the Ganglion Scarpae might be the cause of the Menière symptoms. To confirming the hypothesis, the research plan must be continuously carried out.

Antibodies, Antinuclear↗
PubMed1992

Hearing preservation in acoustic neurinoma surgery.

The chances of hearing conservation in patients with acoustic neurinoma increases by early diagnosis of small tumors. An early diagnosis of an acoustic neurinoma is achieved through the application of a minimal diagnostic test battery to evaluate unilateral otological complaints such as tinnitus, sensorineural hearing loss and balance disturbances. This minimal evaluation comprises puretone audiometry and ABR. Patients showing abnormal findings should be pursued with imaging evaluation such as MRI with gadolinium contrast. The choice of surgical approach for removal of an acoustic neurinoma (transtemporal, translabyrinthine or suboccipital) will depend on the size of the tumor and the patients' hearing. The possibilities should be discussed with the patients. Postponing the surgical intervention due to the possibility of facial paralysis or loss of hearing is difficult to rationalise. During the last 15 years, the development in diagnostic and surgical techniques has made it possible to conserve hearing during surgery at least in some patients suffering from acoustic neurinoma. Early diagnosis of small tumors increases the chances to conserve hearing. Therefore, all nonspecific early otologic symptoms should be thoroughly evaluated to exclude the presence of an acoustic neurinoma. Acoustic neurinomas usually arise within the internal auditory meatus and grow further into the posterior cranial fossa. The first symptoms usually are hearing loss, tinnitus and balance disturbance. These symptoms can occur in combination or individually. Accordingly, all cases presenting with one or all of these symptoms in the absence of an obvious etiology, such as posttraumatic hearing loss, require the exclusion of an acoustic neurinoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Audiometry, Pure-Tone↗
PubMed1990

Immunohistochemical findings in the vestibular ganglion from a patient with Menière's disease.

Immunofluorescent staining techniques were performed on a series of cryostat sections of the vestibular ganglion taken during ganglionectomy from a patient with Menière's disease. The direct technique using FITC-labelled antiserum proved the presence of immunoglobulins in the patient's blood vessels and endoneural connective tissue. Preincubation with unlabelled antiserum blocked this reaction. An additional positive reaction of ganglion cells was demonstrated by incubating tissue with the patient's serum. These findings prove antibodies in the patient's serum against the autologous ganglion cells. The vestibular ganglion from a patient with dizziness following a skull base fracture served as a control specimen. No autoimmune reaction was found in the ganglion cells when incubation was carried out with the patient's serum. A positive reaction in the blood vessels and connective tissue was less pronounced. The findings of the present study underline the occurrence of immunological reactions in the vestibular ganglion of patients with Menière's disease. A subsequent degeneration of ganglion cells could provoke clinical Menière's attacks.

Antigen-Antibody Complex↗
PubMed1990

Determination of cardiac output during positive end-expiratory pressure--noninvasive electrical bioimpedance compared with standard thermodilution.

Many investigators have demonstrated the accuracy and reliability of thoracic electrical bioimpedance (TEB) in spontaneously breathing patients and under mechanical intermittent positive-pressure ventilation. Most of these studies showed a good correlation between TEB and invasive methods, such as thermodilution (TD) or the Fick method. But during PEEP, contrary results occur when comparing TEB and TD. In six patients undergoing neurosurgical interventions, TEB cardiac output measurements were compared during zero end-expiratory pressure (ZEEP) and during PEEP at 8 cm H2O with a low respiratory rate. The data revealed a good correlation during ZEEP (r = .93) and during PEEP (r = .91). There was no significant statistical difference when measuring cardiac output by TEB during ventilation with PEEP. During normal or decreased cardiac output, TEB overestimated cardiac output compared with TD, whereas TEB underestimated cardiac output compared with TD during increased cardiac output, especially during PEEP.

Brain Neoplasms↗
PubMed1988

Otosurgical aspects in diagnostics and therapy of acoustic neurinomas.

136 acoustic neurinomas were operated upon by otosurgical transtemporal or translabyrinthine interventions. The otosurgical approach was used when a suboccipital craniectomy with a certain retraction of the cerebellum seemed to be avoidable. The pure otosurgical tumour removal was restricted to a tumour extension up to 2.5 cm starting from the fundus of the internal auditory meatus. The transtemporal route was used when hearing was worth saving and the translabyrinthine when the pure tone auditogram showed an average loss of 50 dB or the speech audiogram a discrimination loss of 50% or more. In larger tumours the neurosurgeon removed the intracranial part of the acoustic neurinome preserving the facial nerve and, if possible, the cochlear nerve as well. If parts of the tumour had remained within the internal auditory meatus or if some uncertainty concerning complete tumour removal persisted, an otosurgical second intervention was considered indicated. In 41 patients the cochlear nerve could be preserved at operation. 12 of these patients showed a preservation of their hearing.

Audiometry, Pure-Tone↗