Biomedical subjects

J L Parkin

Publications and source records attributed to J L Parkin.

At least 19 recordsLinked to original sources

PubMed1992

Long-term measures of electrode impedance and auditory thresholds for the Ineraid cochlear implant.

Measures of electrode impedance and of detection thresholds for electrical stimuli were extracted from the records of patients implanted with the Ineraid cochlear prosthesis. An analysis of impedance measures, obtained at 1, 12, 24, and 36 months after surgery, demonstrated (a) a significant decrease in impedance over the first year for electrodes that carried current and (b) significant increases in impedance at 24 and 36 months for electrodes that did not carry current. An analysis of detection thresholds, obtained at the same times as the impedance measures, demonstrated that averaged thresholds for the current-carrying electrodes varied no more than 0.5 dB over the 3-year period. These results support the conclusion that stimulation with the Ineraid device does not produce deleterious changes in the electrodes or in the target neural tissue.

Acoustic Impedance Tests↗

PubMed1991

Tumor necrosis factor/cachectin decreases catalase activity of rat liver.

Tumor bearing hosts and animals treated with endotoxin commonly show a decrease in the catalase activity of the liver and kidney. Since tumor necrosis factor (TNF)/cachectin may play a significant role in these conditions, we investigated its effects on the catalatic and peroxidatic activity of catalase in the liver and kidney of the rat. The activities of glucose-6-phosphate dehydrogenase and lactate dehydrogenase were measured simultaneously to monitor the pentose phosphate and glycolytic pathways, respectively. Injection i.p. of 100 micrograms/kg/day human recombinant TNF-alpha for 5 days resulted in a significant (P less than 0.01) decrease in the catalatic activity of the liver when compared to rats fed ad libitum. The decrease in four experiments ranged from 21 to 56%. A significant decrease (18%; P = 0.01) in liver catalatic and peroxidatic activity was also observed in another experiment using pair fed rats as controls. The peroxidatic activity of catalase with ethanol as hydrogen donor closely paralleled the catalatic activity. TNF treatment had no detectable effect on the catalatic or peroxidatic activity of catalase in the kidney. The activity of glucose-6-phosphate dehydrogenase increased (31-80%) significantly (P less than or equal to 0.02) in the liver and, to a lesser extent, in the kidney (5-27%, P = 0.05). Lactate dehydrogenase activity decreased (14-19%) significantly (P less than or equal to 0.05) in the liver and kidney but mainly in rats treated with TNF and additionally fasted for 24 h. Electron microscopic examination of liver sections showed that the hepatocytes of TNF-treated rats were undamaged but contained fewer and smaller peroxisomes than those of the control rats.

Animals↗

PubMed1991

Auditory performance with simultaneous intracochlear multichannel stimulation.

Different sound processing strategies are used in the various cochlear implant designs. This report presents auditory data on 35 patients implanted at the University of Utah from April 1984 to April 1989. A multichannel monopolar electrode system is inserted intracochlearly. During daily use and auditory performance testing, four electrodes receive simultaneous input. The incoming acoustic signal is amplified and routed to the different electrodes through a band-pass filter system. Mean pure-tone performances were: 500 Hz-29.6 +/- 9.4 dB; 1000 Hz-23.5 +/- 13.2 dB; 2000 Hz-25.4 +/- 9.6 dB; 4000 Hz-32.1 +/- 11.5 dB; and 6000 Hz-42.2 +/- 7.7 dB. Audio-only CID sentence testing showed 51.4% of patients scoring better than 60% and 40% scoring better than 80%. The percutaneous pedestal is well tolerated; patients have had the systems in place for 13 and 15 years.

Adolescent↗

PubMed1991

Vowel and consonant recognition with the aid of a multichannel cochlear implant.

In this report we review the vowel and consonant recognition ability of patients who use a multichannel cochlear implant and who achieve relatively good word identification scores. The results suggest that vowel recognition is accomplished by good resolution of the frequency of the first formant (F1) combined with poor resolution of the frequency of the second formant (F2). The results also suggest that consonant recognition is accomplished (1) by using information from the amplitude envelope, including periodicity/aperiodicity, as cues to manner and voicing, (2) by using F1 as an aid to the identification of manner and voicing, and (3) by using information from cochlear place of stimulation to provide a very crude indication of the shape of the frequency spectrum above 1 kHz.

Adult↗

PubMed1991

Acute basophilic leukemia. A clinical, morphologic, and cytogenetic study of eight cases.

The authors describe eight cases of acute basophilic leukemia. In six of the eight cases, basophilic involvement was not apparent by light microscopic examination. The cases were identified on the basis of ultrastructural evidence for basophil/mast cell differentiation of the blasts with little or no differentiation into other lineages. Ultrastructural analysis revealed immature basophil granules in blasts in all eight cases and theta granules in blasts in four cases. In three cases, ultrastructural evidence of mast cell differentiation also was present, with rare cells showing evidence for both basophil and mast cell differentiation. No clinical features distinguished this group of patients from others with acute myeloid leukemia. Cytogenetically, the cases were heterogeneous. Three had a Philadelphia chromosome; none had a t(6;9). The authors conclude that ultrastructural analysis usually must be used to diagnose acute basophilic leukemia, that acute basophilic leukemia is associated frequently with the Philadelphia chromosome, and that the ultrastructural findings provide evidence for a common origin of basophils and mast cells.

Adolescent↗

PubMed1990

Longitudinal changes in word recognition by patients who use the Ineraid cochlear implant.

The time course for reacquisition of spondee word recognition was examined for 27 patients who use the Ineraid cochlear implant. At 1 month postfitting, test scores ranged from 0 to 84% correct. The median score was 10% correct. At 22 to 28 months postfitting, the scores ranged from 0 to 100% correct. The median score was 56% correct. The rate of improvement in spondee recognition varied greatly within the sample. Most patients continued to extract new information from the electrically evoked representation of the speech signal over a period of a year or more.

Cochlear Implants↗

PubMed1990

Percutaneous pedestal in cochlear implantation.

Direct electrical connection between an external sound-processing device and intracochlear electrodes is accomplished via a percutaneous pedestal. Patient pedestal complaints and experience have been recorded. Pedestal problems have been classified into six classes, with class 0 indicating no problems and the severity of problem increasing in classes 1 through 4. Class 5 indicates pedestal trauma. No class 5 problems were encountered. At 48 months of experience, 53% of patients were class 0 and 26% were class 1. The pedestal experience is detailed in the paper. The percutaneous pedestal has been found to be a well-tolerated, efficient system for information transfer in cochlear implant patients.

Cochlear Implants↗

PubMed1990

Selective management of early glottic cancer.

Seventy patients with stage I and II glottic cancer were treated at the University of Utah School of Medicine hospitals from 1980 through 1987. Forty-four patients had stage I cancer and 26 patients had stage II. The overall survival in the stage I group was 82%. Primary site control was 93% with only three deaths due to laryngeal cancer. Local control rates were 93% with CO2 laser excision, 80% with CO2 laser and irradiation, and 67% with radiation alone. Stage II glottic patients had an overall survival of 61.5% with a local control rate of 76%. Twenty-one of 24 patients were treated by full-course irradiation. Of the eight patients who recurred at the primary site, all were irradiation failures who had initial bulky disease and impaired vocal cord mobility. Selective CO2 laser excision was highly effective, whereas radiation therapy results were somewhat disappointing. Open partial laryngectomy should be considered in bulky stage II disease patients.

Adult↗

PubMed1990

Rhinologic applications of laser surgery.

The use of lasers in the treatment of rhinologic conditions is described. Both intranasal and extranasal laser applications are discussed. The choice of an appropriate laser to suit the clinical situation is also examined.

Argon↗

PubMed1990

Lasers in tympanomastoid surgery.

This article describes the lasers available for use by otolaryngologists--head and neck surgeons. It emphasizes the advantages of each type for specific otolaryngologic problems and discusses the considerations for choosing the appropriate laser to treat a particular lesion.

Ear Canal↗

PubMed1989

Mature T-lineage leukemia with growth factor-induced multilineage differentiation.

We report an acute T-lymphoblastic leukemia with a predominantly mature CD3+ CD7+ WT31+ phenotype that was induced to differentiate into different cell lineages by various recombinant human growth factors. In the presence of IL-3 or GM-CSF, the leukemic cells gave rise to myeloid and monocytic cells including terminally differentiated, partially functional, segmented neutrophilic granulocytes as assessed by morphologic, cytochemical, immunophenotypic, and functional criteria. In the presence of IL-2, leukemic granulated lymphoid cells exhibiting MHC-unrestricted cytotoxicity and expressing a CD2+ CD3+ CD5+ CD7+ CD8+ CD33+ WT31+ Leu19+ phenotype arose. Leukemic cell cultures initiated with IL-3 yielded growth factor-independent cells with a mixed lineage phenotype and morphologic and cytochemical evidence of immature blasts. These were T lymphocyte and myeloid surface antigen (CD2,CD3,CD5,CD7,CD13,CD33,WT31) positive. Identical rearrangements of the constant region of the TCR-delta gene and of the joining regions of the TCR-beta, -gamma, and -delta genes were observed in the fresh and all cultured leukemic cells, indicating that they were derived from the same malignant clone. Consistent with the molecular genetic data, the cytogenetic analyses of the GM-CSF-, IL-3-cultured and the growth factor-independent leukemic cells showed the presence of multiple, closely related abnormal clones, all of which had an interstitial deletion of part of the long arm of chromosome 6 and a complex 1;10;12 translocation. In conclusion, these data demonstrate the involvement of a multipotent leukemic precursor cell in this predominantly mature CD2+ CD3+ CD5+ CD7+ WT31+ T-ALL. This multipotent leukemic precursor may be susceptible to various growth factors and respond with ordered differentiation and maturation.

Adult↗

PubMed1989

Prognostic indicators in head and neck cancer patients receiving combined therapy.

In 1983 we initiated a prospective nonrandomized study of the value of preoperative chemotherapy in previously untreated patients with stages III and IV squamous cell carcinoma of the head and neck. In 1983 and 1984, 50 patients were entered in the study. Prior to therapy all patients were evaluated by a representative from the Medical Oncology, Radiation Therapy, and Head and Neck Surgery Divisions, University of Utah School of Medicine, Salt Lake City. In addition to the standard preoperative evaluation, pretreatment computed tomographic scans were performed on all patients. Follow-up computed tomographic scans were performed after the second cycle of chemotherapy and at the completion of treatment. Initial therapy in all patients consisted of induction chemotherapy with cisplatin (day 1, 100 mg/m2) and fluorouracil (days 1 through 5, 1000 mg/m2). Several factors were examined for their utility in predicting response to therapy and survival. Factors evaluated included: (1) extent and timing of chemotherapeutic response; (2) computed tomographic quantitated primary tumor size; (3) size of computed tomographic quantitated regional (neck) metastases; (4) performance status; (5) cancer stage; (6) total lymphocyte count; and (7) serum liver function tests. The factor found to be most useful in predicting improved survival was the extent of response to chemotherapy. The remaining factors, performance status, regional lymph node status, serum gamma-glutamyltransferase levels, and cancer stage, were also found to correlate with length of survival but were much less important than the response to chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1989

Prognosticating speech performance in multichannel cochlear implant patients.

Twenty patients received multichannel cochlear implants between April 1984 and May 1986 at the University of Utah Medical Center. All patients have been followed for at least 1 year postimplant. Preimplant screening included audiometric testing, electronystagmogram (ENG), promontory stimulation, computed tomography (CT) scanning, and psychological evaluation. Based on postimplant audio-only CID sentence discrimination scores, these patients were divided into three groups: good (CID greater than 79%), intermediate (CID, 21% to 79%), and poor (CID less than 21%). Preimplant factors that correlated with CID scores were hearing loss duration, previous use of hearing aids, lip-reading ability, tinnitus, positive ENG calorics, preimplant pure-tone average, promontory stimulation threshold, and understanding of the project. Only previous hearing aid usage approached statistical significance (p = 0.05). A larger patient sample is needed to verify these results.

Adult↗

PubMed1988

Multichannel cochlear implantation: Utah-design.

The Utah-design multichannel cochlear implant consists of six intracochlear monopolar electrodes, one promontory electrode, and an indifferent electrode. Connection of the intracochlear system to the external sound processor is via a percutaneous pedestal system. Four of the intracochlear electrodes receive simultaneous stimulation. Twenty patients implanted at the University of Utah with more than 1 year of sound processor use were evaluated for the study. All patients wear their sound processors on a daily basis. Seven of the 20 are able to use the telephone without special devices. Nineteen patients were tested with open set CID sentences with an average 42.2% response. A comparison was made between live voice and taped voice open-set spondee word list performance, showing slightly better overall performance with live voice.

Adult↗

PubMed1987

Cochlear implant candidates: assessment with CT and MR imaging.

Eighty-seven patients with severe to profound hearing loss were evaluated for possible placement of a multichannel cochlear implant hearing device. After initial clinical screening, 42 patients underwent computed tomographic (CT) examination. Five of these patients were also examined with magnetic resonance (MR) imaging. Twenty-two patients received implants. CT of the middle and inner ear was normal in 24 patients (57.1%) and showed labyrinthine ossification in 12 (28.6%), cochlear or fenestral otosclerosis (or both) in four (9.5%), and congenital cochlear malformation in two (4.8%). The information provided by CT was used to (a) exclude patients in whom multichannel cochlear implantation would most likely be unsuccessful (owing to obliterative labyrinthine ossification, or congenital cochlear malformation, severe cochlear, or fenestral otosclerosis), (b) help select the best ear for implantation, and (c) provide a preoperative picture of normal variants and avoidable surgical pitfalls. MR experience is limited but assessment of the size of the cochlear nerve and the membranous labyrinth is possible with this modality and may provide additional information in the evaluation of these patients.

Adolescent↗

PubMed1987

Vagal neuropathy: evaluation with CT and MR imaging.

The vagus nerve, as a result of its protracted course from the brain stem to the abdomen, can present a difficult imaging problem when it is compromised by a clinically occult lesion. The clinical and radiologic records of 48 patients with suspected vagus nerve dysfunction were reviewed to derive an efficient and effective approach to imaging this patient population. An imaging algorithm is proposed in which vagal neuropathies are divided both clinically and radiologically into proximal and distal categories. Proximal vagal lesions are part of a cranial neuropathy complex and have associated oropharyngeal signs and symptoms (e.g., abnormal gag reflex, uvular deviation). Distal vagal lesions occur as an isolated paralysis of the vagus nerve with no symptoms or signs referable to the oropharynx. Either computed tomography (CT) or magnetic resonance imaging can be used to diagnose proximal or distal lesions. However, CT will be insensitive in the detection of the more cephalic proximal lesions, especially those in the brain stem, basal cisterns, and skull base.

Algorithms↗

PubMed1987

Absorbable gelatin film verses silicone rubber sheeting in orbital fracture treatment.

Orbital floor fractures can result in herniation of orbital tissues and impairment of ocular function. In this experimental study, orbital defects were created surgically in cats. The gross and histologic healing of these defects was compared among animals implanted with silicone rubber sheeting or absorbable gelatin film and animals that received no implants. Both implanted animal groups demonstrated enhancement of healing. The absorbable gelatin film showed less migration, less inflammatory response, and improved healing. This animal study supports the use of absorbable gelatin film in the surgical management of orbital fractures.

Absorption↗

PubMed1987

Immunophenotyping of acute myeloid leukemia using monoclonal antibodies and the alkaline phosphatase-antialkaline phosphatase technique.

The leukemic cells from 41 cases of acute myeloid leukemia (AML) and 17 cases of acute lymphocytic leukemia (ALL) were immunophenotyped by the alkaline phosphatase-antialkaline phosphatase (APAAP) immunocytochemical technique utilizing eight monoclonal antibodies (MoAb) reactive with cells of myeloid origin and seven MoAb reactive with lymphoid antigens. Ninety percent of the cases of AML reacted with one or more of the pan-myeloid MoAb, My7, My9, or 20.3. Reactivity of the myeloid panel of MoAb showed some correlation with the French-American-British (FAB) classification of AML. Five of six cases of acute promyelocytic leukemia (APL) were HLA-DR negative; the one HLA-DR-positive APL had a minor population of HLA-DR-negative promyelocytes. OKM5 and/or My4 reacted with 16 of 16 monocytic leukemias. No specific marker of early erythroid development was identified. AP3, a MoAb reactive with platelet glycoprotein (GPIIIa), was specific for acute megakaryoblastic leukemia. Immunocytochemistry was also helpful in classifying seven cases of AML with equivocal or negative routine cytochemistry. Two cases of AML had minor populations of blasts detected by the APAAP technique that were immunologically distinct from the major blast population; these minor populations emerged as the predominant cell type at relapse. Two cases of ALL expressed multiple myeloid and lymphoid antigens. Two other cases that morphologically were ALL reacted with only myeloid MoAb; one consisted entirely of immature basophils on ultrastructural examination. Immunophenotyping results using the APAAP technique were comparable with those obtained with flow cytometry. The APAAP technique is a reliable method for immunophenotyping leukemia that complements other methods of immunologic evaluation. The primary advantages of this method include its use with routinely prepared blood and bone marrow smears and the ability to correlate immunocytochemical reactions with morphology.

Alkaline Phosphatase↗