Biomedical subjects

M Weiss

Publications and source records attributed to M Weiss.

At least 91 records · Page 5Linked to original sources

PubMed2002

Influence of the emulsion components and preparation method on the laboratory-scale preparation of o/w emulsions containing different types of dispersed phases and/or emulsifiers.

Emulsification is a complex process, strongly influenced by emulsion composition as well as by preparation procedure, and the characterisation of emulsions with regard to their structure and stability can be carried out with many different methods. To evaluate the influences of emulsion composition and preparation procedure on the structure and properties, oil-in-water emulsions were prepared using the model dispersed phase dodecane and the surfactant Tween on the one hand and the real food components sunflower oil (dispersed phase) and casein (emulsifier) on the other hand. The emulsions were prepared in a small laboratory-scale with a turbo-mixer alone and in combination with ultrasonic treatment. The emulsion activity was measured by photometry, the emulsion stability was evaluated visually and the droplet size was determined by laser particle analysis. The results of the investigations made with the model substances agree only partly with those made with the real food substances. For the model emulsions strong correlation were found between the emulsion activity and the particle sizer data because of the high purity and the defined structure of the model substances. On the contrary, for the emulsions made with the real food components sunflower oil and sodium caseinate the correlation were much weaker. Therefore a proper characterisation of the structure and properties of food emulsions requires examinations with several methods which are independent from each other. Furthermore, for laboratory-scale emulsification the combination of turbo-mixer and ultrasonic treatment is suitable to obtain small droplets and a narrow droplet distribution also for very small emulsion volumes.

Emulsions↗

PubMed2002

[Herniotomy in a former preterm infant. Which anaesthetic is best?].

Former preterm infants with postconceptual age <50-60 weeks are at risk of postoperative apnea and bradycardia when operated under general anaesthesia. In addition, after general anaesthesia with endotracheal intubation preterm infants, who had suffered from severe respiratory distress syndrome, often require prolonged postoperative mechanical ventilation. Pure regional anaesthetic techniques can avoid most of these postoperative respiratory complications. Spinal anaesthesia has been used extensively so far. Recently, pure caudal anaesthesia for this indication has become a promising alternative. If a pure regional anaesthesia technique is not indicated or feasable, the combination of light inhalational anaesthesia with a caudal block seems appropriate. Overnight cardiorespiratory monitoring is mandatory in these patients regardless of the anaesthetic technique used.

Anesthesia↗

PubMed2002

T cell reactivity in neonates from an East and a West German city--results of the LISA study.

BACKGROUND: Within an ongoing birth cohort study (LISA) the cytokine production of cord blood T cells was compared between neonates from Leipzig (East Germany) and Munich (West Germany). The aim of this study was to analyse regional differences and influencing factors of the immune status. METHODS: Cytokine production was measured in a randomly selected subgroup of 158 children from the LISA (Life style - Immune system - Allergy) cohort by intracellular cytokine staining. Information on family "atopy" history (FAH) and home characteristics was obtained from questionnaires. RESULTS: Reduced numbers of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) producing T cells were found in association with biparental FAH and housing renovation during pregnancy. In addition, cytokine production was influenced by season. In Munich, the frequency of biparental FAH and of renovation measures during pregnancy was significantly higher as compared to Leipzig. Neonates from Munich showed significantly decreased amounts of IFN-gamma and TNF-alpha and elevated levels of interleukin-4 (IL-4) producing T cells. Differences in cytokine production between Munich and Leipzig were influenced by season (IL-4) and housing renovation (IFN-gamma, TNF-alpha). CONCLUSIONS: Since differences in the T cell cytokine production of neonates in Munich and Leipzig are independent from FAH our findings may provide evidence for the impact of environmental factors upon the fetal immune system.

Cohort Studies↗

PubMed2002

[Non-typical measurements during a isokinetic training session after ACL-reconstruction].

Rehabilitative resistance work programs after ACL-injuries are derived from programs known from competitive sports training. The development of different parameters (max. Power output, total work per set) was examined in 12 patients after ACL-reconstruction during a training session on an isokinetic training machine with a velocity of 120 degrees /sec and 60 degrees /sec. The results let suppose that neuromuscular structures of patients with ACL-reconstruction react different to those of healthy people in the control group. Therefore the rehabilitation programs have to be adjusted to the recruitment pattern of motor units after ACL-injury. In this case there has to be a progression of intensity during the isokinetic training session.

Adult↗

PubMed2002

Influence of seasonal variations in training loads on selected amino acids and parameters of the psychoimmunological network in a swimming team.

In the last years a shift in amino acid profile was discussed as one reason for the development of staleness. Signs of staleness are among others susceptibility to infection and disturbances in well-being. Beside tryptophane and branched-chain amino acids (BCAA) glutamine is the most discussed amino acid (AA) in this context. Based on the hypothesis of a multifactorial genesis of staleness and these AA being the metabolic link in psychoimmunology, seven young swimmers of regional top level were examined in a longitudinal field monitoring for biochemical, biomechanical and psycho-physiological data at six different training phases across one year. Special interest was spent on phases with the highest training loads (HT I and II) because of the increased risk of appearance of staleness compared with the regeneration phase (RP). The results point out that well controlled and regulated HT does not reduce but increases the plasma levels of glutamate (means and SD; RP 20 +/- 8 micromol/l, HT I 34 +/- 11 micromol/l), glutamine (RP 489 +/- 155 micromol/l, HT I 634 +/- 113 micromol/l) and BCAA (valine RP 164 +/- 54 micro mol/l, HT I 283 +/- 58 micromol/l, isoleucine RP 59 +/- 20 micromol/l, HT I 101 +/- 24 micromol/l, leucine RP 88 +/- 32 micromol/l, HT I 142 +/- 35 micro mol/l). The immunological parameters did not show any significant training-induced changes (sIL-2-R: RP 422 +/- 98 U/ml, HT I 522 +/- 70 U/ml, s-ICAM: RP 157 +/- 11 ng/ml, HT I 185 +/- 32 ng/ml) and don't seem to be suitable as indicators for a "biochemical-psychophysiological" justified control and regulation of training. Possibly the increasing of plasma concentrations of AA by intensive and high volume endurance training is the "store shape" of AA in view of saving and provisioning the organism for further exhausting training loads.

Adolescent↗

PubMed2002

A case of idiopathic nodular glomerulosclerosis mimicking diabetic glomerulosclerosis (Kimmelstiel-Wilson type).

A case of idiopathic nodular glomerulosclerosis mimicking diabetic Kimmelstiel-Wilson glomerulopathy is reported. The patient was a 45-year-old man suffering from nephrotic syndrome. Light and electron microscopy revealed diffuse and nodular glomerulosclerosis indistinguishable from diabetic nodular glomerulosclerosis. Diabetes mellitus, however, had been excluded both by extensive clinical and by laboratory investigation. The differential diagnosis also included amyloidotic and non-amyloidotic fibrillary glomerulopathy, light chain glomerulopathy, collagen type III disease, immunotactoid glomerulopathy, and the sclerosing variant of membranoproliferative glomerulonephritis. Immunohistochemistry and ultrastructural investigations, however, excluded these entities, and the diagnosis of idiopathic nodular glomerulosclerosis was made. This variant has to be included in the differential diagnosis of nodular glomerulopathy associated with nephrotic syndrome.

Amyloidosis↗

PubMed2002

Variability in infusion pressure and continuous flow rate delivered from pressurized bag pump flush systems.

Using 10 different infusion bag pressure pumps, indicated manometer pressures were compared with measured infusion pressures proximal to the flow-regulating device in an in vitro experiment. Flow rates delivered through the flow-regulating device were gravimetrically measured at different monitored pressure levels. Significant differences were found between manometer and measured infusion pressures among the tested pressure bagpumps (e.g. 500 ml bag volumepressurized to 300 mmHg manometerpressure: 219.6 +/- 7.8 to 407.2 +/- 2.7 mmHg). The infusion pressures were additionally affected by the vertical level of the infusion bag pump and by the volume of the infusion bag. Flow rates delivered through the flow-regulating device were directly correlated to the measured infusion pressure (r2= 0.9926). Differences inflow rates can have a considerable impact on maintaining catheter patency and avoidance of fluid overload and retrograde flushing into the central arterial circulation in neonates and small children. A simple manoeuvre using the invasive pressure transducer allows monitoring and adjustment of the infusion pressure in the clinical setting.

Humans↗

PubMed2002

Factors affecting performance of air tonometry using the TONOCAP.

Saline tonometry has been replaced by automated air tonometry (TONOCAP). As with saline tonometry there are some pitfalls to consider. We investigated the influence of different filling handicaps to the tonometry catheter sampling balloon on measurement of regional PCO2 (PrCO2). In an in vitro set-up, PrCO2 was measured using the TONOCAP at intervals of 10 minutes from a 8F tonometry catheter sampling balloon placed in a container with constant PCO2 (PcCO2). Catheter alarms displayed by the TONOCAP device were noted. The following experiments were performed: A) control measurement without modifications; B) adding deadspace of 7 ml into the sampling line; C) placing the sampling balloon in a 3 ml syringe; D) cross-clamping of the sampling balloon. Each experiment was performed four times using two catheters on two TONOCAP devices. Differences between PcCO2 and PrCO2 were calculated as Pc-rCO2. Results are presented as mean +/- SD and were compared using ANOVA with Scheffe's correction. Pc-rCO2 in the control set-up (A) amounted to 0.16 +/- 0.22%. Increasing catheter deadspace (B) resulted in a higher Pc-rCO2 of 3.2 +/- 0.57% (P < 0.0001). Restriction of balloon expansion (C) caused an Pc-rCO2 gap of 1.17 +/- 0.36% (P < 0.0001). With filling restriction (D) the Pc-rCO2 gap increased to 3.87 +/- 0.29% (P < 0.0001). The catheter alarms provided were not able to indicate all catheter problems and initial alarms disappeared although the problems continued. We conclude that impaired catheter deadspace to balloon volume relation can negatively influence accuracy of PrCO2 measurement by the TONOCAP.

Carbon Dioxide↗

PubMed2002

Allergens and endotoxin on mothers' mattresses and total immunoglobulin E in cord blood of neonates.

The current authors examined whether mite and cat allergen and bacterial endotoxin levels in dust of the mothers' mattresses were associated with cord blood immunoglobulin (Ig)E (CB-IgE) levels in newborns. Data from 1,332 term and normal weight neonates, from an ongoing birth cohort study, influences of life-style related factors on the immune system and the development of allergies in childhood (LISA), with complete information on exposure to biocontaminants in mattress dust and CB-IgE were analysed. Two thirds of CB-IgE were undetectable (<0.35 kU x L(-1)). Thus, 0.35 and 0.45 kU x L(-1) (4th quartile) were chosen as cut-offs. Nonparametric smoothing (generalised additive models) showed statistically significant confounder-adjusted associations between elevated CB-IgE levels (> or = 0.45 kU x L(-1)) and log-transformed exposures to cat (linear), mite (inverse u-shaped), and endotoxin (u-shaped). After adjustment for covariables, elevated CB-IgE levels (logistic regression using the 1st-4th quartiles of exposure) were positively associated with high cat-allergen exposure and medium exposure to mite allergen, but were inversely associated with exposure to endotoxin. The associations were similar, but somewhat weaker, when 0.35 kU x L(-1) was used as cut-off. These results, showing an association between prenatal allergen and endotoxin exposures and immunoglobulin E production, suggest that the development of foetal immune responses may be affected.

Allergens↗

PubMed2002

Distribution kinetics of solutes in the isolated in-situ perfused rat head using the multiple indicator dilution technique and a physiological two-barrier model.

The purpose of this study was to determine the pharmacokinetics of [14C]diclofenac, [14C]salicylate and [3H]clonidine using a single pass rat head perfusion preparation. The head was perfused with 3-[N-morpholino] propane-sulfonic acid-buffered Ringer's solution. 99mTc-red blood cells and a drug were injected in a bolus into the internal carotid artery and collected from the posterior facial vein over 28 min. A two-barrier stochastic organ model was used to estimate the statistical moments of the solutes. Plasma, interstitial and cellular distribution volumes for the solutes ranged from 1.0 mL (diclofenac) to 1.6 mL (salicylate), 2.0 mL (diclofenac) to 4.2 mL (water) and 3.9 mL (salicylate) to 20.9 mL (diclofenac), respectively. A comparison of these volumes to water indicated some exclusion of the drugs from the interstitial space and salicylate from the cellular space. Permeability-surface area (PS) products calculated from plasma to interstitial fluid permeation clearances (CL(PI)) (range 0.02-0.40 mL s(-1)) and fractions of solute unbound in the perfusate were in the order: diclofenac > salicylate > clonidine > sucrose (from 41.8 to 0.10 mL s(-1)). The slow efflux of diclofenac, compared with clonidine and salicylate, may be related to its low average unbound fraction in the cells. This work accounts for the tail of disposition curves in describing pharmacokinetics in the head.

Animals↗

PubMed2002

[Diagnosis of initial changes in the hand of patients with rheumatoid arthritis--comparison between low-field magnetic resonance imaging, 3-phase bone scintigraphy and conventional x-ray].

UNLABELLED: Besides conventional X-rays, in the diagnostic work up of initial changes in patients suffering from rheumatoid arthritis (RA), 3-phase bone scintigraphy (3P-Sz) is as well established as magnetic resonance imaging (MRI). The aim of this study was to compare the diagnostic value of the newly developed low field MRI with the proven methods X-rays and 3P-Sz. METHODS: 65 patients (47f, 18m; 20-86 yrs) were studied on a one day protocol with 3P-Sz (550 MBq Tc-99m DPD), MRI and X-rays of the hands. Images were visually analysed by two blinded nuclear medicine physicians and radiologists and classified as a) RA-typical, b) inflammatory, non-RA-typical and c) non inflammatory changes. All methods were compared to 3P-Sz as golden standard. RESULTS: In comparison to 3P-Sz, low field MRI presents with almost equal sensitivity and specificity in rheumatoid-typical and inflammatory changes. Conventional X-rays revealed in arthritis-typical changes as well as in inflammatory changes a significantly lower sensitivity and also a lower negative predictive value while specificity equals the one of MRI. Quantitative analysis of 3P-Sz using ROI-technique unveiled significantly higher values in patients with rheumatoid arthritis than in those with no inflammatory changes. CONCLUSION: MRI represents an equally sensitive method in the initial diagnosis of rheumatoid-typical and inflammatory changes in the region of the hands as compared to the 3P-Sz. Besides the basic diagnosis with conventional X-rays, 3P-Sz is still the recommended method of choice to evaluate the whole body when RA is suspected. Additionally, quantitative analysis of the 3P-Sz using the ROI technique in the region of the hands reveals statistically significant results and should therefore be taken into account in the assessment of inflammatory changes.

Adult↗

PubMed2001

Sorting of Golgi resident proteins into different subpopulations of COPI vesicles: a role for ArfGAP1.

We present evidence for two subpopulations of coatomer protein I vesicles, both containing high amounts of Golgi resident proteins but only minor amounts of anterograde cargo. Early Golgi proteins p24alpha2, beta1, delta1, and gamma3 are shown to be sorted together into vesicles that are distinct from those containing mannosidase II, a glycosidase of the medial Golgi stack, and GS28, a SNARE protein of the Golgi stack. Sorting into each vesicle population is Arf-1 and GTP hydrolysis dependent and is inhibited by aluminum and beryllium fluoride. Using synthetic peptides, we find that the cytoplasmic domain of p24beta1 can bind Arf GTPase-activating protein (GAP)1 and cause direct inhibition of ArfGAP1-mediated GTP hydrolysis on Arf-1 bound to liposomes and Golgi membranes. We propose a two-stage reaction to explain how GTP hydrolysis constitutes a prerequisite for sorting of resident proteins, yet becomes inhibited in their presence.

ADP-Ribosylation Factor 1↗

PubMed2001

CD64 surface expression on neutrophils is transiently upregulated in patients with septic shock.

OBJECTIVE: To clarify the changes in total leukocyte counts, CD64 neutrophil receptor expression and serum granulocyte colony-stimulating factor (G-CSF) concentrations in critically ill patients without infection and sepsis and in patients with septic shock. DESIGN: Prospective study. SETTING: Intensive care unit (ICU) and research laboratory of a university hospital. PATIENTS: Eleven critically ill patients without infections and 22 patients with proven infections in septic shock for the first time and of at least 3 days' duration. MEASUREMENTS AND RESULTS: Over a 6month period, a longitudinal analysis of expression of the monomeric Fc receptor type I (CD64, FcgammaRI) on neutrophils was performed by flow cytometric analysis on a daily basis in all postoperative/post-traumatic patients admitted to the ICU until discharge from the ICU or death. Out of 273 patients, 11 patients without sepsis had organ failure and 22 patients with proven infections had septic shock for the first time and of at least 3 days' duration. Ten out of the 22 patients survived, 12 died. CD64 expression was greater in patients with septic shock than in patients without sepsis. Moreover, CD64 expression was only initially and transiently elevated in most survivors (9/10) and non-survivors (8/12) of septic shock. In survivors, G-CSF serum concentrations were markedly decreased in the 2nd week. CONCLUSIONS: Decreased neutrophil CD64 expression in an acutely ill population with septic shock may reflect the development of a non-responsive state as well as the early downregulation of neutrophil activation prior to the resolution of an ongoing infection.

Aged↗

PubMed2001

Early postmenopausal bone loss in hyperthyroidism.

OBJECTIVES: To evaluate the effect of hyperthyroidism on bone in relation to the menopausal state. METHODS: Fifty-nine hyperthyroid (HYPER), 40 hypothyroid (HYPO), and 51 control euthyroid (EUTH) women were studied. Bone mineral density (BMD) was assessed by dual X-rays absorptiometry (DXA) at the lumbar spine, and at the femoral neck. A multi-site QUS device evaluated speed of sound (SOS) at the radius (RAD), tibia (TIB), metatarsus (MTR), and phalanx (PLX). Bone markers used were serum bone specific alkaline phosphatase (BSAP) and urinary deoxypyridinoline (DPD). RESULTS: At all sites, SOS was lower in HYPER than in EUTH (RAD P<0.05, TIB P<0.01, MTR P<0.05, PLX P=0.01). The low SOS was only noted at the early postmenopausal period. BMD at the femoral neck but not at the lumbar spine was lower in HYPER as compared to EUTH (P<0.05). Both femoral neck and tibia were the sites with the highest odds ratio for being hyperthyroid (2.3 and 2.04, respectively). There was no correlation between BMD or SOS and FT(4), TT(3) or duration of hyperthyroidism. BSAP and DPD positively correlated with FT(4) and TT(3) (P<0.05). CONCLUSIONS: This study suggests that hyperthyroidism affects bone mineralization especially during the early postmenopausal period, and the effect is mainly at the cortical bone.

Absorptiometry, Photon↗

PubMed2001

Drop metastasis from sinonasal undifferentiated carcinoma: clinical implications.

STUDY DESIGN: The first reported case of multiple intradural, extramedullary spinal metastasis from sinonasal undifferentiated carcinoma is presented. OBJECTIVES: To elucidate the mechanisms by which metastatic disease invades the spinal axis, and to discuss the possibility of spinal drop metastasis from head and neck tumors that invade the dura. SUMMARY OF BACKGROUND DATA: Sinonasal undifferentiated carcinoma is a rare yet aggressive neoplasm of the upper airways and anterior skull base. This neoplasm is known to invade the cranial vault and brain locally. However, it has not previously been reported to seed the cerebrospinal fluid or result in drop metastasis. Such drop metastasis may result in significant neurologic deficit if not diagnosed and treated in a timely manner. METHODS: This report is based on a single patient treated by a multidisciplinary team from the departments of neurosurgery, otolaryngology, and radiation oncology at the University of Southern California School of Medicine. RESULTS: This patient initially underwent resection and local radiation therapy for sinonasal undifferentiated carcinoma of the anterior skull base. At the time of surgery, the tumor was noted to violate the dura and arachnoid along the subfrontal plane. At 11/2 years after the initial treatment, a bandlike distribution developed at T2 as well as paresthesias and numbness below that level. Imaging of the spine showed an intradural, extramedullary tumor at T2 consistent with a schwannoma or meningioma. The patient underwent a laminectomy and tumor resection, which showed poorly differentiated sinonasal carcinoma. Local radiation therapy was administered, and the patient experienced complete recovery of neurologic function. Bilateral leg pain and weakness developed 14 months later. Magnetic resonance imaging of the spine showed a new intradural, extramedullary lesion at T12, remote from the first lesion. This second metastasis was managed with surgical resection and adjuvant radiation therapy. CONCLUSIONS: This is the first reported case of a sinonasal carcinoma leading to intradural extramedullary metastasis. The primary tumor likely seeded the cerebrospinal fluid, thus resulting in drop metastasis. Patients with sinonasal undifferentiated carcinoma that invades the dura should be monitored closely for evidence of metastasis before symptoms develop.

Carcinoma↗

PubMed2001

Differences in the expression of CD64 and mCD14 on polymorphonuclear cells and on monocytes in patients with septic shock.

The present study was performed to clarify the time course of the expression of CD64, the Fc gamma receptor type I (FcgammaR1), and membrane-bound CD14 (mCD14), one of the major receptors for endotoxin, on polymorphonuclear leukocytes (PMN) and monocytes in 22 postoperative/post-traumatic patients with septic shock. Therefore, the expression of CD64 and mCD14, and serum concentrations of granulocyte colony-stimulating factor (G-CSF) and interferon-gamma (IFN-gamma) were determined by flow cytometric analysis and enzyme-linked immunosorbent assay (ELISA), respectively, from the first day of septic shock onwards over a period of 14 days. When compared to the values of 12 healthy controls, CD64 expression was elevated significantly on PMN and monocytes of the patients, whereas the expression of mCD14 was decreased significantly at all days. The initially increased expression of CD64 on PMN and monocytes decreased within the first days of septic shock. The already initially decreased mCD14 expression decreased further on PMN, but not on monocytes. Serum concentrations of G-CSF and IFN-gamma during the study period were significantly higher than those of the control group. The differences in the kinetics of CD64 and mCD14 expression in patients with septic shock may be explained by different regulatory effects of cytokines, such as G-CSF and IFN-gamma.

Adult↗

PubMed2001

Evaluation of the FASTSTART mode for reducing start-up delay in syringe pump infusion systems.

OBJECTIVE: The aim of the study was to evaluate the IVAC P7000 FASTSTART mode with regard to start-up performance in a 50-ml infusion syringe at a flow rate of 1 ml.h-1. METHODS: The time from depression of the start button to first fluid flow (T1) and to establishment of a pre-set flow rate (T2) were gravimetrically recorded with and without FASTSTART and with and without priming of the infusion system with a 1-ml fluid bolus prior to connection of the infusion line to the patient. RESULTS: FASTSTART significantly reduced start-up times in the unprimed syringe pump infusion system from (mean [SD]) 9.4 (6.0) to 2.5 (3.5) min for T1 and from 21.8 (9.8) to 9.4 (6.2) min for T2 (all p < 0.001). The greatest improvement in shortening of T1 and T2 was obtained when the system was primed prior to starting (p < 0.0001). After priming the infusion system, FASTSTART shortened T2 by some 50% from 1.4 (1.4) to 0.7 (0.6) min. CONCLUSION: Our data indicate that the FASTSTART procedure is effective and that substantial improvements can be obtained by priming the system prior to starting.

Catheterization, Central Venous↗

PubMed2001

Taming chaos by impurities in two-dimensional oscillator arrays.

The effect of impurities in a two-dimensional lattice of coupled nonlinear chaotic oscillators and their ability to control the dynamical behavior of the system are studied. We show that a single impurity can produce synchronized spatiotemporal patterns, even though all oscillators and the impurity are chaotic when uncoupled. When a small number of impurities is arranged in a way, that the lattice is divided into two disjoint parts, synchronization is enforced even for small coupling. The synchronization is not affected as the size of the lattice increases, although the impurity concentration tends to zero.

Journal Article↗