Biomedical subjects

C Hess

Publications and source records attributed to C Hess.

At least 19 recordsLinked to original sources

PubMed2006

Cluster clinics for migrant Hispanic farmworkers with diabetes: perceptions, successes, and challenges.

INTRODUCTION: Diabetes is a chronic disease that requires individuals to schedule multiple office visits with a multidisciplinary team to learn how to successfully manage and delay the progression of complications. To respond to the health-care and educational needs of Hispanic migrant farmworkers who travel to Minnesota and North Dakota, the Migrant Health Service Inc diabetes program coordinator implemented evening cluster clinics. The purpose of this research project was to describe Hispanic migrant farmworkers' perceptions of the services provided to them at 37 multidisciplinary cluster clinics designed to serve this rural population diagnosed with diabetes. METHODS: This descriptive research employed a questionnaire and individual interviews. Both quantitative and qualitative data were obtained from cluster clinic clients. Quantitative data consisted of the numbers and percentages of clients providing various responses to questionnaire items. The qualitative data consisted of the verbal responses of clients to two open-ended questionnaire items and to an interview protocol. RESULTS: The main findings of the project indicated that 75-88% of the clients rated the services provided at the 37 cluster clinics as 'excellent'; an additional 21-25% rated them as 'good.' More than 85% of the clients indicated either that 'nothing should be changed' (59%) or that 'everything was fine' (26%). These ratings and content analysis of the interview data revealed that the clients perceived they had received quality services at these cluster clinics. The authors also discuss six characteristics that they believed contributed to the successful delivery of health care and education through cluster clinics. These characteristics include: (1) provision of both direct and referral services for this underserved population; (2) comprehensive delivery of services in a single setting; (3) collaborative delivery of services; (4) access-driven delivery of services; (5) delivery of culturally-sensitive and linguistically-appropriate services; and (6) evidence-based service delivery. CONCLUSIONS: Cluster clinics are an effective way to improve health-care services, education, and counseling for the under-served or unserved Hispanic migrant population diagnosed with diabetes. The authors conclude with four primary challenges to the implementation of these cluster clinics which include: (1) locating and preparing facilities; (2) recruiting health-care providers for the clinics; (3) achieving effective, appropriate communication with clients; and (4) securing funding.

Adult↗

PubMed2006

[Hearing impairment in children and adolescents with Down's syndrome].

BACKGROUND: There are controversial opinions about the incidence of hearing impairment of children and adolescents with Down's syndrome as an additional cause for obstruction in social and communicative live. Next to congenital diseases of the inner ear, functional limitations can often lead to conductive hearing disorders in patients with Down's syndrome. PATIENTS AND METHODS: The hearing ability, otoscopic and audiometric characteristics of 115 patients aged 3.2+/-2.9 years were analysed retrospectively over 42 months. RESULTS: A total of 86 children showed morphologic otoscopic peculiarities: transitory evoked otoacoustic emissions (TEOAE) were often non-reproducible, even in patients with normal hearing abilities(14.1% of cases), and were not evaluable in 32.8% of cases. Half of the patients showed hearing loss, 82% of whom suffered from a conductive hearing loss, 6.9% from a combined, and 8.6% from isolated sensorineural hearing loss. Hearing loss was first diagnosed when the children were 4.6+/-3.4 years old. CONCLUSION: The frequent occurrence of hearing loss justifies and requires an early and continuous pedaudiological examination. As a common screening examination, TEOAE is limited due to its cost, however, it fulfils its purpose as a means of distinguishing healthy children from those with possible hearing disorders. In most cases, objective and subjective audiometric methods must be combined in order to precisely define the hearing ability.

Adolescent↗

PubMed2004

Magnon-hole scattering and charge order in Sr14-xCaxCu24O41.

The magnon thermal conductivity kappa(mag) of the hole-doped spin ladders in Sr14-xCaxCu24O41 has been investigated at low doping levels x. The analysis of kappa(mag) reveals a strong doping and temperature dependence of the magnon mean free path l(mag), which is a local probe for the interaction of magnons with the doped holes in the ladders. In particular, this novel approach to studying charge degrees of freedom via spin excitations shows that charge ordering of the holes in the ladders leads to a freezing out of magnon-hole scattering processes.

Journal Article↗

PubMed2003

Electronic excitation and dynamic promotion of a surface reaction.

The mechanism of recombinative desorption of hydrogen from a Ru(0001) surface induced by femtosecond-laser excitation has been investigated and compared to thermally initiated desorption. For the laser-driven process, it is shown that hot substrate electrons mediate the reaction within a few hundred femtoseconds resulting in a huge isotope effect between H2 and D2 in the desorption yield. In mixed saturation coverages, this ratio crucially depends on the proportions of H and D. Deviations from second order desorption kinetics demonstrate that the recombination is dynamically promoted by excitation of neighboring, but nonreacting adatoms. A concentration dependent rate constant which accounts for the faster excitation of H versus D is proposed.

Journal Article↗

PubMed2003

Magnon heat transport in doped La2CuO4.

We present results of the thermal conductivity of La2CuO4 and La(1.8)Eu(0.2)CuO4 single crystals which represent model systems for the two-dimensional spin-1/2 Heisenberg antiferromagnet on a square lattice. We find large anisotropies of the thermal conductivity which are explained in terms of two-dimensional heat conduction by magnons within the CuO2 planes. Nonmagnetic Zn substituted for Cu gradually suppresses this magnon thermal conductivity kappa(mag). A semiclassical analysis of kappa(mag) is shown to yield a magnon mean free path which scales linearly with the reciprocal concentration of Zn ions.

Journal Article↗

PubMed2003

Autoantibodies against complement receptor 1 (CD35) in SLE, liver cirrhosis and HIV-infected patients.

The acquired loss of CR1 (CD35) on erythrocytes in specific autoimmune diseases and chronic infections may be due to autoAb against CR1. An ELISA using rCR1 was established to measure antiCR1 IgG autoAb. Plasma containing alloAb to polymorphism on CR1 (Knops blood group Ab) reacted strongly against rCR1 and were used as positive controls. AntiCR1 Ab was found in 3/90 (3.5%) plasma samples from healthy blood donors. The binding of these Ab was not inhibited by high salt concentrations. AntiCR1 Ab were present in the IgG fractions of plasma, and they bound to rCR1 on Western Blot. Affinity chromatography on rCR1-sepharose depleted the plasma of antiCR1, and the acid-eluted fractions contained the antiCR1 Ab. An increased frequency of antiCR1 autoAb was found in patients with SLE (36/78; 46%), liver cirrhosis (15/41; 36%), HIV infection (23/76; 30%) (all P < 0.0001), and in patients with anticardiolipin Ab (4/21; 19%, P < 0.01) multiple sclerosis (7/50; 14%, P < 0.02), and myeloma (autoAb (8/56; 14%, P < 0.02), but not in those with acute poststreptococcal glomerulonephritis (1:32; 3%). Because C1q binds to CR1, antiC1q Ab were analysed in the same patients. There was no correlation between levels of antiC1q and antiCR1 autoAb. In HIV patients, levels of antiCR1 did not correlate with low CR1 levels expressed on erythrocytes or soluble CR1 in plasma. The binding of antiCR1 autoAb to rCR1 fixed on ELISA plates was not inhibited by soluble rCR1 or by human erythrocyte CR1, in contrast to alloAb and one SLE serum, which induced partial blockade. Thus, antiCR1 autoAb recognize mostly CR1 epitope(s) not present on the native molecule, suggesting that they are not directly involved in the loss of CR1. Rather antiCR1 autoAb might indicate a specific immune response to denatured CR1.

Autoantibodies↗

PubMed2003

Adjuvant vs. neoadjuvant radiochemotherapy for locally advanced rectal cancer: the German trial CAO/ARO/AIO-94.

AIM: The standard treatment for patients with clinically resectable rectal cancer is surgery. Postoperative radiochemotherapy (RCT) is recommended for advanced disease (pT3/4 or pN+). In recent years, encouraging results of pre-operative radiotherapy have been reported. This prospective randomized phase-III-trial (CAO/ARO/AIO-94) compares the efficacy of neoadjuvant RCT to standard postoperative RCT. We report on the design of the study and first results with regard to toxicity of RCT and postoperative morbidity. PATIENTS AND METHODS: Patients with locally advanced operable rectal cancer (uT3/4 or uN+, Mason CS III/IV) were randomly assigned to pre or postoperative RCT: A total dose of 50.4 Gy (single dose 1.8 Gy) was applied to the tumour and the pelvic lymph nodes. 5-FU (1000 mg/m2/d) was administered concomitantly in the 1th and 5th week of radiation as 120 h-continuous infusion. Four additional cycles of 5-FU-chemotherapy (500 mg/m2/d, i.v.-bolus) were applied. RCT was identical in both arms except for a small-volume boost of 5.4 Gy postoperatively. The time interval between RCT and surgery was 4-6 weeks in both arms. Techniques of surgery were standardized and included total mesorectal excision. Primary endpoints of the study are 5-year survival and local and distant control. Secondary endpoints include the rate of curative (R0) resection and sphincter saving procedures, toxicity of RCT, surgical complications and quality of life. RESULTS: As of July 2002, 805 patients were randomized from 26 participating institutions. Acute toxicity (WHO) of RCT was low, with less than 15% of patients experiencing grade 3 or higher toxicity: The principal toxicity was diarrhea, with 12% in the postoperative RCT-arm and 11% in the pre-operative RCT-arm having grade 3-, and 1% in either arm having grade 4-diarrhea. Erythema, nausea and leukopenia were the next common toxicities, with less than 3% of patients in either arm suffering grade 3 or greater leukopenia or nausea. Postoperative complication rates were similar in both arms, with 12% (postop. RCT) and 12% (pre-op. RCT) of patients, respectively, suffering from anastomotic leakage, 3% (postop. RCT) and 3% (pre-op. RCT) from postoperative bleeding, and 6% (postop. RCT) and 4% (pre-op. RCT) from delayed wound healing. CONCLUSION: The patient accrual to the trial is satisfactory. Neoadjuvant RCT is well tolerated and bears no higher risk for postoperative morbidity.

Adult↗

PubMed2001

Effect of VEGF receptor inhibitor PTK787/ZK222584 [correction of ZK222548] combined with ionizing radiation on endothelial cells and tumour growth.

The vascular endothelial growth factor (VEGF) receptor is a major target for anti-angiogenesis-based cancer treatment. Here we report the treatment effect of ionizing radiation in combination with the novel orally bioavailable VEGF receptor tyrosine kinase inhibitor PTK787/ZK222584 on endothelial cell proliferation in vitro and with tumour xenografts in vivo. Combined treatment of human umbilical vein endothelial cells with increasing doses of PTK787/ZK222584 and ionizing radiation abrogated VEGF-dependent proliferation in a dose-dependent way, but inhibition of endothelial cell proliferation was not due to apoptosis induction. In vivo, a combined treatment regimen of PTK787/ZK222584 (4 x 100 mg/kg) during 4 consecutive days in combination with ionizing radiation (4 x 3 Gy) exerted a substantial tumour growth delay for radiation-resistant p53-dysfunctional tumour xenografts derived from SW480 colon adenocarcinoma cells while each treatment modality alone had only a minimal effect on tumour size and neovascularization. SW480 tumours from animals that received a combined treatment regimen, displayed not only an extended tumour growth delay but also a significant decrease in the number of microvessels in the tumour xenograft. These results support the model of a cooperative anti-tumoral effect of angiogenesis inhibitor and irradiation and show that the orally bioavailable VEGF receptor tyrosine kinase inhibitor PTK787/ZK222584 is suitable for combination therapy with irradiation.

Adenocarcinoma↗

PubMed2001

Novel surface vibrational spectroscopy: infrared-infrared-visible sum-frequency generation.

A novel type of surface vibrational sum-frequency generation spectroscopy is presented that enables a highly specific measurement of the coupling of molecules on surfaces. With this doubly vibrationally resonant technique, two-dimensional vibrational spectroscopy of molecules on surfaces becomes possible. The technique is demonstrated for the C-O stretch vibration of CO on a ruthenium (001) surface. It allows for the determination of the intermolecular coupling strength of dipole-coupled CO molecules on the surface.

Journal Article↗

PubMed2001

Key targets for the execution of radiation-induced tumor cell apoptosis: the role of p53 and caspases.

In many human hematologic and solid malignancies, intrinsic or acquired treatment resistance remains a major obstacle for successful cancer therapy. The molecular understanding of how tumor cells respond to chemotherapy and ionizing radiation is rapidly evolving. Induction of programmed cell death, apoptosis, is one important strategy for successful cancer therapy. This has been shown convincingly for oncogene-transformed normal cells as well as tumor cells of lymphoid origin. However, the relevance of apoptosis in solid human malignancies is less clear. Loss of apoptosis might be linked to specific mutations in the often tissue-specific apoptotic pathways due to aberrations in the stress-related signal transduction cascades. Restoration of a dysfunctional apoptotic program in cancer tissue where apoptosis has been identified as an important mechanism for tissue homeostasis is one rational approach for innovative cancer therapy. In this review, we focus on the relevance of the tumor suppressor p53 for apoptosis-induction and successful cancer therapy outlining the importance of an intact caspase machinery for apoptosis execution. Strategies are discussed to overcome treatment resistance and a high apoptotic threshold in human malignancies where apoptosis is the dominant mode of cell death and the status of p53 is an important determinant for apoptosis induction.

Adenoviridae↗

PubMed2001

Adjuvant versus neoadjuvant radiochemotherapy for locally advanced rectal cancer. A progress report of a phase-III randomized trial (protocol CAO/ARO/AIO-94).

AIM: The standard treatment for patients with clinically resectable rectal cancer is surgery. Postoperative radiochemotherapy is recommended for patients with advanced disease (pT3/4 or pN+). In recent years, encouraging results of preoperative radiotherapy have been reported. This prospective randomized phase-III trial (CAO/ARO/AIO-94) compares the efficacy of neoadjuvant radiochemotherapy to standard postoperative radiochemotherapy. We report on the design of the study and first results with regard to toxicity of radiochemotherapy and postoperative morbidity. PATIENTS AND METHODS: Patients with locally advanced operable rectal cancer (uT3/4 or uN+, Mason CS III/IV) were randomly assigned to pre- or postoperative radiochemotherapy: A total dose of 50.4 Gy (single dose 1.8 Gy) was applied to the tumor and the pelvic lymph nodes. 5-FU (1,000 mg/m2/d) was administered concomitantly in the first and fifth week of radiation as 120-h continuous infusion. Four additional cycles of 5-FU chemotherapy (500 mg/m2/d, i.v. bolus) were applied. Radiochemotherapy was identical in both arms except for a small-volume boost of 5.4 Gy in the postoperative setting. Time interval between radiochemotherapy and surgery was 4-6 weeks in both arms. Techniques of surgery were standardized and included total mesorectal excision. In addition, stratification according to surgeons involved has been provided for. Primary endpoints of the study are 5-year overall-survival, local and distant control, secondary endpoints include rate of curative (R0) resections and sphincter saving procedures, toxicity of radiochemotherapy, surgical complications and quality of life. RESULTS: As of 15th November 2000, 628 patients were randomized from 26 participating institutions: 310 patients were randomized to postoperative radiochemotherapy, 318 patients to preoperative radiochemotherapy. Acute toxicity (WHO) of radiochemotherapy was low, with less than 15% of patients experiencing Grade 3 or higher toxicity: The principal toxicity was diarrhea, with 12% in the postoperative radiochemotherapy arm and 10% in the preoperative radiochemotherapy arm having Grade-3, and 1% in either arm having Grade-4 diarrhea. Erythema, nausea and leukopenia were the next common toxicities, with less than 3% of patients in either arm suffering Grade 3 or greater leukopenia or nausea. Postoperative complication rates were similar in both arms, with 12% (postoperative radiochemotherapy) and 13% (preoperative radiochemotherapy) of patients, respectively, suffering from anastomotic leakage, 4% (postoperative radiochemotherapy) and 3% (preoperative radiochemotherapy) from postoperative bleeding, and 6% (postoperative radiochemotherapy) and 5% (preoperative radiochemotherapy) from delayed wound healing. CONCLUSION: The patient accrual of our trial is satisfactory, neoadjuvant radiochemotherapy is well tolerated and bears no higher risk for postoperative morbidity.

Adult↗

PubMed2001

Melatonin protects SHSY5Y neuroblastoma cells from cobalt-induced oxidative stress, neurotoxicity and increased beta-amyloid secretion.

Heavy metals are increasingly being implicated as causative agents in neurodegenerative diseases such as Alzheimer's disease (AD). Cobalt, a positively charged transition metal, has previously been shown to be in elevated levels in the brain of AD patients compared with age-matched controls. In this study, we investigate the effects of cobalt as an inducer of oxidative stress/cell cytotoxicity and the resultant metabolic implications for neural cells. We show that cobalt is able to induce cell cytotoxicity (reduced MTT metabolism) and oxidative stress (reduced cellular glutathione). The pre-treatment of cells with the pineal indoleamine melatonin, prevented cell cytotoxicity and the induction of oxidative stress. Cobalt treatment of SHSY5Y cells increased the release of beta-amyloid (Abeta) compared with untreated controls (ratio Abeta 40/42). Melatonin pre-treatment reversed the deleterious effects of cobalt. These findings are significant as cobalt is an essential nutritional requirement, usually bound to cobalamin (vitamin B12), for all animals which in the unbound form could lead to neurotoxicity.

Alzheimer Disease↗

PubMed2001

The first activating TSH receptor mutation in transmembrane domain 1 identified in a family with nonautoimmune hyperthyroidism.

Sporadic and familial nonautoimmune hyperthyroidism are very rarely occurring diseases. Within the last years constitutively activating TSH receptor mutations were identified as one possible pathomechanism. Except for S281N in the extracellular N-terminal domain, all other germline mutations are located in the transmembrane domains 2, 3, 5, 6, and 7 of the TSH receptor, whereas no mutation was reported in transmembrane domains 1 and 4 to date. Here we report the first family with a constitutively active TSHR mutation in transmembrane domain 1 resulting in a substitution of the conserved Gly(431) for Ser. This mutation was found in the investigated patient, his father, and the paternal grandmother. As known from other familial cases of nonautoimmune hyperthyroidism, the age of onset of the disease was variable, ranging from early childhood in the patient and his father to adolescence in the grandmother. Functional characterization of this mutation showed a constitutive activation of the G(s)/adenylyl cyclase system. Moreover, this germline mutation also activates the G(q/11)/phospholipase C pathway. The importance of Gly(431) for receptor quiescence is supported further by introduction of other mutations at this position, all leading to constitutive receptor activity. Our data show now that constitutively activating mutations can be found in the entire transmembrane domain region of the TSH receptor, indicating the important role of all parts of the transmembrane domain region for maintaining the inactive receptor conformation.

Adenylyl Cyclases↗

PubMed2000

Direct observation of vibrational energy delocalization on surfaces: CO on Ru(001)

We report the experimental observation of the gradual transition from a local oscillator to a two-dimensional delocalized phonon, observed for the CO-stretch vibration of carbon monoxide adsorbed on a Ru(001) surface by means of broadband-infrared saturation sum-frequency spectroscopy. The data are theoretically reproduced by an exchange model with residence times of the excitation down to 2.5 ps.

Journal Article↗

PubMed2000

Induction of neutrophil responsiveness to myeloperoxidase antibodies by their exposure to supernatant of degranulated autologous neutrophils.

Antibodies against myeloperoxidase (MPO) and proteinase 3 (PR3) are the predominant autoantibodies present in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Their binding to the corresponding antigen on the surface of polymorphonuclear neutrophils (PMNs) is believed to trigger the disease process. Cytokines released during an inflammatory reaction are thought to prime resting PMNs, making them responsive to autoantibodies. In the present study we found that MPO but not PR3 could be detected on the cell surface of unstimulated PMNs after incubation with the supernatants of activated autologous PMNs. MPO was shown to be acquired from these supernatants, because PMNs did not express MPO when the supernatants were specifically MPO-depleted. In addition, purified soluble MPO bound to unstimulated PMNs. Unstimulated PMNs that had passively acquired MPO released oxygen radicals when incubated with monoclonal antibody anti-MPO or the immunoglobulin G fraction of a patient with MPO-ANCA. The data presented here suggest that, in ANCA-associated vasculitis, soluble MPO released by activated PMNs may bind to unstimulated PMNs, thereby making them reactive to anti-MPO antibodies. This mechanism of dispersing PMN activation would be specific for MPO-ANCA and may explain differences in the pathologic and clinical expression of MPO-ANCA versus PR3-ANCA vasculitis. (Blood. 2000;96:2822-2827)

Adsorption↗

PubMed2000

[Adolescent crisis with cyclic abdominal complaints and regressive behavior].

In this 18 year old female patient with adolescent crisis, psychic regression and cyclic abdominal pain, the diagnosis of an acute intermittent porphyria was made by positive urine finding of porphobilinogen, by low serum measurement of the enzyme urosynthase and the positive genetic mutation of this enzyme. The article gives a brief report of the pathogenesis, clinical findings, diagnostic tests and the current therapies being undertaken. Further, a list of medications which are indicated or contraindicated relating to the patient with acute intermittent porphyria is noted.

Abdominal Pain↗

PubMed2000

Femtosecond surface vibrational spectroscopy of CO adsorbed on Ru(001) during desorption

Using time-resolved sum-frequency generation spectroscopy, the C- O stretch vibration of carbon monoxide adsorbed on a single-crystal Ru(001) surface is investigated during femtosecond near-IR laser excitation leading to desorption. A large transient redshift, a broadening of the resonance, and a strong decrease in intensity are observed. These originate from coupling of the C- O stretch to low-frequency modes, especially the frustrated rotation, that are highly excited in the desorption process.

Journal Article↗

PubMed2000

Thermal and electronic transport properties and two-phase mixtures in La(5/8-x)Pr(x)Ca(3/8)MnO3

We measured thermal conductivity kappa, thermoelectric power S, and electric conductivity sigma of La(5/8-x)Pr(x)Ca(3/8)MnO3, showing an intricate interplay between metallic ferromagnetism (FM) and charge ordering (CO) instability. The change of kappa, S, and sigma with temperature (T) and x agrees well with the effective medium theories for binary metal-insulator mixtures. This agreement clearly demonstrates that with the variation of T as well as x, the relative volumes of FM and CO phases drastically change and percolative metal-insulator transition occurs in the mixture of FM and CO domains.

Journal Article↗