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Biomedical subjects

M M Hess

Publications and source records attributed to M M Hess.

32 records · Page 2Linked to original sources
PubMed1997

Effect of acute phase response on phenytoin metabolism in neurotrauma patients.

The purpose of this prospective study was to correlate measures of the acute phase response, associated therapeutic interventions, and other clinical variables with the process of altered drug metabolism previously observed in patients with severe neurotrauma. Nine patients with severe head injury (Glasgow Coma Scale < or = 8) requiring intravenous phenytoin were included in the study. A loading dose of phenytoin was followed by daily maintenance doses. Serial blood samples were taken after the loading dose and every even-numbered study day for 10 to 14 days for measurement of total and unbound concentrations of phenytoin, interleukin-1 beta, interleukin-6 (IL-6), tumor necrosis factor alpha, alpha 1-acid-glycoprotein, C-reactive protein, and albumin. Time-invariant and time-variant Michaelis-Menten models were fit to the phenytoin concentration-time data. Protein intake was closely monitored. The mean (+/- SEM) unbound fraction of phenytoin increased from 0.17 +/- 0.02 on day 1 to 0.24 +/- 0.04 on day 10 (P < 0.05). The time-variant model was superior in describing the concentration-time data of unbound phenytoin in eight of nine patients. Mean (+/- SEM) pharmacokinetic parameter estimates for unbound phenytoin were: Vmax delta = 605 +/- 92 mg/day, VmaxB = 149 +/- 26.3 mg/day, K(ind) = 0.013 +/- 0.004 hr-1. Interleukin-6 was the only cytokine with significant concentration changes over time; it was inversely correlated with Vmax,t. Peak concentrations of interleukin-6 also proved to be inversely correlated with VmaxB. The daily amount of protein administered was significantly correlated with Vmax,t. Significant alterations in the metabolism of phenytoin occur after severe neurotrauma. The etiology of these changes is probably multifaceted. These results suggest that low initial phenytoin Vmax may be explained by the presence of interleukin-6. An increase in oxidative metabolism that correlated with nutritional protein administration was observed later in these patients.

Acute-Phase Reaction↗
PubMed1996

[Endoscopic imaging of vocal cord vibrations. Digital high speed recording with various systems].

Vocal fold vibration patterns during phonation are presented with different digital imaging systems. With newly developed technical equipment color images up to 1000 digital images/s were obtained without light intensifying enhancement techniques via rigid and flexible endoscopy. With this color high-speed system, morphologic structures, such as small blood vessels, were visualized in high-resolution quality as a result of additional color information. In another system, zooming of endoscopic pictures via pixel interpolation algorithms provided full-monitor presentation of vocal fold vibratory patterns. This system allows PC-based synchronization with microphone and electroglottographic signals in a frame-by-frame technique. Although only processing gray scale images, analyses of dynamic changes in modes of vibration were facilitated by the higher frame rate recording of up to 2000 frames/s and, in addition, they display corresponding analog signals. Both methods provide clinically important information. Furthermore, we demonstrated irregular vocal fold vibration patterns in a healthy adult volunteer. In this experiment, the irregular vibratory modes were induced by voluntarily applying asymmetric vocal fold tension. The asymmetric vocal fold vibration pattern resulted in (functionally induced) roughness of the voice as predicted by computer models of asymmetric vocal fold vibration. Digital high-speed cinematography proved to be a highly promising technique in the analysis of dysphonia and provided physiological examples that could be compared with models of coupled nonlinear oscillators.

Adult↗
PubMed1994

Superiority of aztreonam/clindamycin compared with gentamicin/clindamycin in patients with penetrating abdominal trauma.

There were 73 evaluable patients entered into a prospective, double-blinded trial comparing aztreonam/clindamycin (A/C) to gentamicin/clindamycin (G/C) for the prevention of infection after penetrating abdominal trauma. Aztreonam was administered at a dosage of 2 g every 8 hours and gentamicin at 5 mg/kg for the first 24 hours and then adjusted by serum monitoring to a peak of 6 to 8 micrograms/mL and a trough of less than 2 micrograms/mL; all patients received 900 mg of clindamycin every 8 hours. Patients with colon wounds received 4 days of antibiotics, and the remaining patients received a 24-hour course. Gunshot wounds occurred in 69% of patients: 74% of all patients had some hollow viscus injury, and 26% had only solid viscus injury. The groups were well matched according to abdominal trauma index, percentage with colon injury, and transfusion requirements. Failures occurred in eight patients (11%): two wound infections, five intra-abdominal infections, and one case of necrotizing fasciitis. Seven infections occurred in 36 (19%) G/C patients compared with 1 in 37 (3%) A/C patients (p < 0.03). The hospital stay was 12 +/- 11 days for G/C patients and 8 +/- 7 for A/C patients (p < 0.12). The superiority of the A/C regimen may be partially attributable to relative underdosing of gentamicin (approximately half of the patients had inadequate levels after 24 hours) combined with a favorable pharmacokinetic profile (significantly prolonged half-life) of aztreonam in this clinical setting.

Abdominal Injuries↗
PubMed1994

Cytogenetic abnormalities in B-immunoblastic lymphoma.

We have considered the cytogenetic abnormalities present in 27 unpublished cases of B-immunoblastic lymphoma. Among these 27 patients, the chromosome changes were heterogeneous and complex. The chromosomes most commonly gained were 3 (44% of cases), 18 (44%), 6 (30%) and 11 (30%). The most common structural abnormalities involved band 14q32 (26%), band 18q21 (15%) and bands 6q16-21 (19%). Study of these 27 immunoblastic lymphomas did not allow us to tentatively identify a common primary cytogenetic abnormality unique to B-immunoblastic lymphoma, however, a translocation at 14q32 may be the primary cytogenetic lesion in some of the cases. Rather, we have added to the number of abnormalities reported in immunoblastic lymphoma and in non-Hodgkin's lymphoma in general.

Adolescent↗
PubMed1993

High-speed, light-intensified digital imaging of vocal fold vibrations in high optical resolution via indirect microlaryngoscopy.

Digital imaging of vocal fold vibrations is mainly limited by lighting problems. We present a new technique for high optical resolution of vocal fold vibrations (via indirect microlaryngoscopy) using a light intensifier camera. Superficial epithelial structures and secretions can be followed during vibrations by means of high magnification. Recordings of up to 2.4 seconds and 6,000 frames per second, combined with simultaneous recording of acoustic and electroglottographic signals, are possible. This technique allows instant slow-motion monitor control and subsequent documentation on a normal video recording system. We also present preliminary findings of typical vocal fold motion patterns.

Female↗
PubMed1992

[Experimental study of airflow in the main nasal cavity of the human using a nose model].

Airflow patterns of nasal cavities in a human nasal fossa model were examined in this study. Our 1:1 model of the whole nose (both nasal fossae were moulded) gives a good insight into all parts of the nasal cavities. Staining of flow paths visualised that the main stream of air flow passes through the inferior nasal duct in inspiration and expiration. All regions of the nasal fossa were reached by fluid movements and could be marked with staining solution. Under static conditions laminar flow without turbulent profiles was seen in all sections of the nasal cavities. This technique of detection of flow characteristics in the nasal cavities provides a good tool for further research on flow and deposition characteristics of aerosols.

Humans↗
PubMed1991

[Measuring evoked otoacoustic emissions at various times during intubation anesthesia].

Evoked otoacoustic emissions (EOAE) remain intraindividually similar in repeated measurements. After application of medication for general anesthesia no significant changes of EOAE could be seen. Damping of amplitude and energy, mostly seen in the late phase of general anesthesia, might be caused by possible middle ear pressure changes from nitrous oxide. The recording of EOAE under general anesthesia provides an additional method in objective infant hearing evaluation and expands our diagnostic tools in those cases when children do not cooperate.

Anesthesia, General↗
PubMed1991

[Neuro-otologic diagnosis after long-term exposure to wood preservatives containing pentachlorophenol].

We examined the possible vestibulotoxicity of 16 patients subject to chronic exposure to wood preservatives containing pentachlorophenol. A vestibular test battery showed no abnormal findings except in one patient with pre-existing Menière's disease. The discrepancy between a clear history of exposure contrasted with the normal vestibular finding, and illustrates the diagnostic problems in patients chronically exposed to wood preservative.

Adult↗
PubMed1990

[Aerodynamics of respiratory flow in the nasopharynx].

The authors present a new technique for studying airflow patterns and particle deposition in the nasopharynx. The nasal cavities and the nasopharynx from the head of a human cadaver were filled with siliconrubber and a "positive" model was then produced by moulding with plastic. An apparatus was constructed to provide calibrated flow of propandiol in both directions. Flow characteristics were visualized by introducing small particles in suspension or by injecting methylene blue with a needle. In addition, test aerosol was drawn in through the model to demonstrate dust deposition sites in the nasopharynx. In the future, this method will enable us to examine the nasopharyngeal airflow patterns and deposition sites of inhaled particles.

Airway Resistance↗
PubMed1990

Cytogenetic findings in a primary malignant fibrous histiocytoma of bone and the lung metastasis.

Cytogenetic studies were performed on a malignant fibrous histiocytoma of bone and its metastasis to lung. Numerical chromosome abnormalities were described for all chromosomes except chromosomes 2, 4 and 16. Structural abnormalities in the primary tumor involved chromosomes 1, 3, 5, 10, 11, 13, 15, 16 and 17. The chromosomal rearrangements seen both in the primary tumor and its metastasis involved chromosomes 13, 15 and 17. Two X chromosomes contained large homogeneously staining regions (HSRs) in the primary tumor which were replaced by multiple double minutes (DMs) in the metastatic tumor.

Bone Neoplasms↗
PubMed1990

[Diagnosis and therapy of benign paroxysmal positional vertigo].

The clinical features and therapeutical aspects of 31 patients with benign paroxysmal positional vertigo (BPPV) were studied. Attention is drawn to diagnostic criteria such as the "Hallpike manoeuvre" and guidelines are given for the differentiation of BPPV and cervical nystagmus. The results of this study are discussed with special regard to habituation training.

Female↗
PubMedDate not supplied

Trimethoprim-sulfamethoxazole pharmacokinetics in trauma patients.

STUDY OBJECTIVES: To characterize the pharmacokinetic profile of trimethoprim-sulfamethoxazole (TMP-SMX) in trauma patients and to compare these parameter estimates with those obtained in nontrauma patients. DESIGN: Open-label, multidose, pharmacokinetic study. SETTING: Trauma intensive care unit of a level 1 trauma center located within a regional medical center. PATIENTS: Fifteen adult trauma patients with serious gram-negative infections. All patients were studied on day 1 of treatment, nine on day 3, three on day 5, and two on day 7. One patient was discontinued from the study because of a possible drug-induced rash. INTERVENTIONS: Study patients received TMP 4 mg/kg and SMX 20 mg/kg intravenously every 12 hours. Serial blood sampling was performed up to 4 times per patient between treatment days 1 and 7. Serum was assayed for TMP-SMX using high-performance liquid chromatography. A one-compartment model was fit to the data using maximum likelihood estimation. MEASUREMENTS AND MAIN RESULTS: Mean (SD) baseline parameter estimates for TMP were volume 2.1 (0.65) L/kg, half-life 9.7 (3.0) hours, and clearance 2.6 (0.80) ml/min/kg. Estimates for SMX were volume 0.51 (0.10) L/kg, half-life 7.8 (2.0) hours, and clearance 0.80 (0.29) ml/min/kg. Both volume (p < 0.01) and clearance (p < 0.001) for SMX were significantly higher and half-life (p < 0.05) significantly shorter than previously reported estimates in nontrauma patients. No significant differences in TMP parameter estimates were found. Neither TMP nor SMX clearance was significantly correlated with estimated creatinine clearance (p > 0.05). CONCLUSION: The results indicate that the pharmacokinetics of SMX in trauma patients differ significantly from nontrauma patients, which may result in lower than expected concentrations using standard dosing guidelines.

Accidents↗
PubMedDate not supplied

Pharmacokinetics of aztreonam and imipenem in critically ill patients with pneumonia.

STUDY OBJECTIVE: To evaluate the pharmacokinetic profiles of aztreonam and imipenem in critically ill trauma patients with pneumonia. METHODS: Trauma patients in intensive care units who were intubated within 3 days of hospital admission were eligible for the study. Patients with the clinical diagnosis of pneumonia were consecutively randomized to receive either aztreonam plus vancomycin or imipenem-cilastatin. Serial blood samples were taken and sputum was collected to determine aztreonam and imipenem concentrations after 2-3 days and 7-8 days of therapy. Pharmacokinetics of both agents were estimated and compared with estimates from healthy volunteers. RESULTS: Twenty patients were enrolled in the study, 10 patients received imipenem-cilastatin, and 10 received aztreonam plus vancomycin. Steady-state volume of distribution (Vss) for aztreonam at 2-3 days and 7-8 days was significantly greater in patients than in historical controls, whereas the Vss for imipenem was greater at 2-3 days. The beta-half-life for aztreonam at both sampling periods was significantly greater in patients than in controls. No significant changes in pharmacokinetics occurred over time for either antibiotic. Sputum concentrations of aztreonam and imipenem were highly variable when sampled 2 hours after the infusion. CONCLUSION: Larger volumes of distribution were observed for both aztreonam and imipenem in trauma patients than in volunteers, suggesting that standard initial dosages of the antibiotics may result in lower concentrations in these critically ill patients. Both antibiotics penetrated into the sputum of most patients; however, the degree of penetration was highly variable in relation to serum concentrations.

Adolescent↗