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Biomedical subjects

J Richter

Publications and source records attributed to J Richter.

At least 73 records · Page 4Linked to original sources
PubMed2001

Productivity, quality, and patient satisfaction: comparison of part-time and full-time primary care physicians.

CONTEXT: Although few data are available, many believe that part-time primary care physicians (PCPs) are less productive and provide lower quality care than full-time PCPs. Some insurers exclude part-time PCPs from their provider networks. OBJECTIVE: To compare productivity, quality of preventive care, patient satisfaction, and risk-adjusted resource utilization of part-time and full-time PCPs. DESIGN: Retrospective cohort study. SETTING: Boston. PARTICIPANTS: PCPs affiliated with 2 academic outpatient primary care networks. MEASUREMENTS: PCP productivity, patient satisfaction, resource utilization, and compliance with screening guidelines. RESULTS: Part-time PCP productivity was greater than that of full-time PCPs (2.1 work relative value units (RVUs)/bookable clinical hour versus 1.3 work RVUs/bookable clinical hour, P< .01). A similar proportion of part-time PCPs (80%) and full-time PCPs (75%) met targets for mammography, Pap smears, and cholesterol screening (P = .67). After adjusting for clinical case mix, practice location, gender, board certification status, and years in practice, resource utilization of part-time PCPs (138 dollars [95% confidence interval (CI), 108 dollars to 167 dollars]) was similar to that of full-time PCPs (139 dollars [95% CI, 108 dollars to 170 dollars], P = .92). Patient satisfaction was similar for part-time and full-time PCPs. CONCLUSIONS: In these academic primary care practices, rates of patient satisfaction, compliance with screening guidelines, and resource utilization were similar for part-time PCPs compared to full-time PCPs. Productivity per clinical hour was markedly higher for part-time PCPs. Despite study limitations, these data suggest that academic part-time PCPs are at least as efficient as full-time PCPs and that the quality of their work is similar.

Academic Medical Centers↗
PubMed2001

Optical coherence tomography of the esophagus and proximal stomach in health and disease.

OBJECTIVE: Surveillance of Barrett's esophagus is problematic, as high-grade dysplasia cannot be recognized endoscopically. Endoscopic ultrasound lacks the resolution to detect high-grade dysplasia. Optical coherence tomography (OCT) employs infrared light reflectance to provide in vivo tissue images at resolution far superior to endoscopic ultrasound, nearly at the level of histology. We have developed a catheter-based system well suited for study of the GI tract. The purpose of this study was to test this catheter-based OCT system and characterize the OCT appearance of normal squamous mucosa, gastric cardia, Barrett's esophagus, and carcinoma. METHODS: The OCT catheter was passed through the operating channel of the endoscope and placed in contact with the esophageal mucosa. Image acquisition occurred in approximately 3 s. OCT images were correlated with biopsy and/or resection specimens. RESULTS: OCT was used to construct 477 images of the esophagus and stomach in 69 patients. There were unique, distinct OCT appearances of squamous mucosa, gastric cardia, Barrett's esophagus, and carcinoma. Further, these OCT images were accurately recognized by observers unaware of their site of origin. CONCLUSIONS: OCT provides a highly detailed view of the GI wall, with clear delineation of a multiple layered structure. It is able to distinguish squamous mucosa, gastric cardia, Barrett's esophagus, and cancer. This technique holds great potential as an adjunct to the surveillance of patients with Barrett's esophagus, ulcerative pancolitis, and other premalignant conditions.

Adenocarcinoma↗
PubMed2001

Doctors' authoritarianism in end-of-life treatment decisions. A comparison between Russia, Sweden and Germany.

OBJECTIVES: The study was performed in order to investigate how end-of-life decisions are influenced by cultural and sociopolitical circumstances and to explore the compliance of doctors with patient wishes. PARTICIPANTS AND MEASUREMENT: Five hundred and thirty-five physicians were surveyed in Sweden (Umeå), Germany (Rostock and Neubrandenburg), and in Russia (Arkhangelsk) by a questionnaire. The participants were recruited according to availability and are not representative. The questionnaire is based on the one developed by Molloy and co-workers in Canada which contains three case vignettes about an 82-year-old Alzheimer patient with an acute life-threatening condition; the questionnaire includes different levels of information about his treatment wishes. We have added various questions about attitudes determining doctors' decision making process (legal and ethical concerns, patient's and family wishes, hospital costs, patient's age and level of dementia and physician's religion). RESULTS: Swedish physicians chose fewer life-prolonging interventions as compared with the Russian and the German doctors. Swedish physicians would perform cardiopulmonary resuscitation (CPR) in the event of a cardiac arrest less frequently, followed by the German doctors. More than half the Russian physicians decided to perform CPR irrespective of the available information about the patient's wishes. Level of dementia emerged as the most powerful determining attitude-variable for the decision making in all three countries. CONCLUSIONS: The lack of compliance with patient wishes among a substantial number of doctors points to the necessity of emphasising ethical aspects both in medical education and clinical practice. The inconsistency in the treatment decisions of doctors from different countries calls for social consensus in this matter.

Advance Directives↗
PubMed2001

Report of the second satellite symposium on ultrasound in schistosomiasis.

A group of experts on schistosomiasis and ultrasonography discussed the experiences and results obtained with the Niamey-Belo Horizonte Protocol on Ultrasonography in Schistosomiasis. A series of recommendations about qualitative and quantitative data obtained by ultrasound in studies performed in Africa and Brazil are presented. Immunological, genetic and epidemiological studies must rely on ultrasound for the identification of patients with periportal thickening/fibrosis.

Africa↗
PubMed2001

Distributions by age and sex of the dimensions of temperament and character inventory in a cross-cultural perspective among Sweden, Germany, and the USA.

Distribution by age and sex of the dimensions of the Temperament and Character Inventory were assessed cross-culturally for samples in Sweden, Germany, and the USA. The Temperament and Character Inventory is a 240-item (Sweden, 238-item), self-administered, true-false format, paper-and-pencil test developed by Cloninger and his coworkers based on his unified biosocial theory of personality. The inventory measures the Temperament dimensions Novelty Seeking, Harm Avoidance, Reward Dependence, and Persistence as well as the Character dimensions, Self-directedness, Cooperativeness, and Self-transcendence. The samples consisted of 300 German subjects, 300 Swedish subjects, and 300 U.S. subjects matched by age cohort and sex. Stability of the personality dimensions was evaluated across samples as were their age and sex distributions. We found significant effects of age, sex, and culture in univariate and multivariate comparisons on the personality dimensions. However, several significant differences in the personality dimensions for both European samples appear to be similar compared with those of the U.S. sample. We have to conclude that sex- and age-specific norms for the dimensions of the Temperament and Character Inventory are necessary given the established significant differences.

Adolescent↗
PubMed2001

Malaria and tourism: retrospective analysis of German malaria cases imported from the Dominican Republic.

We report on malaria acquired by German tourists to formerly non-endemic tourist resorts in the Dominican Republic between July 1999 and March 2000. Falciparum malaria is endemic in the western provinces and the hinterland of the Dominican Republic. By contrast, the risk of contracting malaria has always been considered so low in the main tourist resorts in the eastern part of the country that antimalarial chemoprophylaxis was not recommended.

Disease Outbreaks↗
PubMed2001

Molecular cytogenetic alterations associated with rapid tumor cell proliferation in advanced urinary bladder cancer.

Invasive urinary bladder carcinomas are characterized by a high number of cytogenetic alterations which are thought to pinpoint the location of critical genes, some of which may be involved in cell cycle control. To identify genomic alterations that may affect such genes the proliferative activity (Ki67 labeling index) was assessed in 93 invasively growing bladder carcinomas analyzed by comparative genomic hybridization. Only a few changes were significantly associated with rapid tumor cell proliferation, including 3p+ (p=0.0357), 6p+ (p=0.003), 8q+ (p=0.0273), and 11q- (p=0.0329). Among these alterations 6p+ is of particular interest because high level 6p22 amplifications occur frequently in bladder cancer. The particular strong association between 6p+ and a high tumor cell proliferation being independent of grade and stage suggests that a putative oncogene on 6p22 involved in cell cycle regulation.

Carcinoma, Transitional Cell↗
PubMed2001

Tree models for dependent copy number changes in bladder cancer.

We analyzed comparative genomic hybridization data on a collection of 237 bladder cancer tumors with the aim of identifying sets of copy number aberrations (CNAs) that tend to occur together. A test based on Fisher's exact test for pairs, but taking into account multiple testing, showed strong dependencies amongst several pairs of aberrations including (+1q, -11p), (+17q, +20q), (+10p, -17p), (-8p, -17p), (+5p, +10p). To determine whether co-occurrence of CNAs may characterize tumor subtypes, we used two recently proposed methods to construct tree models of tumor progression. We constructed tree models for all the tumors, the tumors of stage pT1, and the tumors of stages pT2-4. The tree models confirmed that most of the non-random events and the associations are the same for different stages. We conclude that the combination of large data sets and tree models provide a useful approach to systematically identifying tumor subgroups characterized by more than a single chromosomal aberration.

Algorithms↗
PubMed2000

Construction of evolutionary tree models for renal cell carcinoma from comparative genomic hybridization data.

Renal cell carcinoma is characterized by an accumulation of complex chromosomal alterations during tumor progression. Chromosome 3p deletions are known to occur early in the carcinogenesis, but the nature of subsequent events, their interrelationships, and their sequence is poorly understood, as one usually only obtains a single "view" of the dynamic process of tumor development in a particular cancer patient. To address this limitation, we used comparative genomic hybridization analysis in combination with a distance-based and a branching-tree method to search for tree models of the oncogenesis process of 116 conventional (clear cell) renal carcinomas. This provides a means to analyze and model cancer development processes based on a more dynamic model, including the presence of multiple pathways, as compared with the fixed linear model first proposed by Vogelstein et al. (N. Engl. J. Med., 319: 525-532, 1988) for colorectal cancer. The most common DNA losses involved 3p (61%), 4q (50%), 6q (40%), 9p (35%), 13q (37%), and Xq (21%). The most common gains were seen at chromosome 17p and 17q (20%). The tree model derived from the distance-based method is consistent with the established theory that -3p is an important early event in conventional (clear cell) renal cancer and supports the prediction made from the branching tree that -4q is another important early event. Both tree models suggest that there may be two groups of clear cell renal cancers: one characterized by -6q, +17q, and + 17p, and another by -9p, -13q, and -18q. Putative prognostic parameters were -9p and -13q. The distance-based tree clarifies that -8p (present in 12% of tumors) is a late event, largely independent of other events. In summary, tree modeling of comparative genomic hybridization data provided new information on the interrelationships of genetic changes in renal cancer and their possible order, as well as a clustering of these events. Using tree analysis, one can derive a more in-depth understanding of the renal cancer development process than is possible by simply focusing on the frequencies of genetic events in a given cancer type.

Carcinoma, Renal Cell↗
PubMed2000

Evolution of schistosomiasis-induced pathology after therapy and interruption of exposure to schistosomes: a review of ultrasonographic studies.

Ultrasonography (US) is suitable for diagnosing schistosomiasis-related organic pathology and is particularly useful to assess its evolution after therapy and/or interruption of exposure to the Schistosoma parasites. Evolution of pathology after treatment: Regression of hepatic abnormalities in Schistosma mansoni-infected children and adolescents has been observed already from 7 months post-therapy on. This does, however, not occur in all cases: individual differences are great ranging from spontaneous regression of pathology without treatment to persistence of pathology lasting for years after therapy even without re-infection. Intensity and duration of exposure, different parasite strains, patients' age and genetic background all influence the evolution of pathology. In communities at continuous exposure to S. mansoni infection, repeated re-treatment is required to control hepatosplenic morbidity. In Schistosoma japonicum infection, changes around the portal tree may regress, but characteristic diffuse abnormalities described as 'network pattern' abnormalities do not resolve. In Schistosoma haematobium infection bladder abnormalities and urinary tract obstruction frequently resolve after treatment. Clinically relevant pathology may resurge from 1 year after therapy on if exposure continues. Subjects with more advanced pathology before therapy, appear to be at higher risk of pathology re-appearance. Evolution of pathology after interruption of exposure to schistosomiasis: Knowledge on the evolution of pathology induced by S. mansoni is limited to some reports in emigrants and to the experience of ultrasonographists working in areas, where transmission has been partially interrupted. Due to the longevity of the parasite, infection may last for many years. Even after elimination of the parasites severe pathology may persist for long. In S. haematobium infection spontaneous healing after interruption of re-exposure may occur, but cases have been reported where urogenital lesions led to complications many years after exposure. Contrary to hepatosplenic and urinary pathology, knowlegde on the evolution of other organic abnormalities is very limited: studies on the evolution of biliary abnormalities or intestinal pathology have not been published. Genital pathology may be induced by all Schistosoma spp. Post-therapy evolution of genital schistosomiasis is largely ignored. In some European travellers partial regression of prostatic fibrosis has been described. Schistosomal adnexitis leading to infertility and/or ectopic pregnancy has been reported occurring many years after interruption of exposure. Ultrasonography (US) has never been used to study the influence of schistosomiasis on pregnancy. Concluding, current knowlegde on the evolution of pathology after treatment and/or interruption of exposure is still fragmentary. Frequently, fibrosis reverses after therapy, but advanced pathology may persist for long. Therefore, the possibility of severe clinical complications has to be taken into account, even if the infection is inactive since many years. In interventions aimed at controlling schistosomiasis-related morbidity, evolution of pathology must be monitored by US in representative patient cohorts. Further systematic US-studies are needed not only on the evolution of hepatosplenic and urinary pathology but also on that of intestinal, biliary and genital pathology induced by schistosomiasis, as well as on the influence of schistosomiasis on the outcome of pregnancy.

Adolescent↗
PubMed2000

Intercalated clear cells or pale cells in the sinus node of canine hearts? An ultrastructural study.

Two types of sinus nodal cells were responsible for the main differences in the literature concerning the ultrastructure of the sinuatrial node: the intercalated clear cells and pale cells. Canine hearts were arrested by (1) aortic cross clamping, (2) coronary perfusion with the cardioplegic solution St. Thomas, and (3) coronary perfusion with the cardioplegic solution HTK (Custodiol(R)). After fixation by immersion or perfusion the sinus node tissue was prepared for electron microscopy. Following cardioplegic arrest and perfusion fixation, three nodal cell types in the non-ischemic sinuatrial node were observed: typical nodal cells, transitional cells, and intercalated clear cells. Less than 1% of the non-ischemic sinuatrial cells were intercalated clear cells, surrounded by typical nodal cells or transitional cells. The contractile apparatus of the intercalated clear cells was extremely poorly developed. Great structural variations in the mitochondria were observed in intercalated clear cells, variations that would not appear under conditions of ischemia. In contrast, after 15-25 min of ischemia at 25 degrees C the appearance of the sinus nodal cells was strikingly different from that of the non-ischemic sinuatrial cells. More than 10% of the nodal cells showed typical ischemic alterations, e.g., mitochondrial swelling, clumping of nuclear chromatin, loss of glycogen particles, and cell swelling in varying degrees. Because they look very pale, these nodal cells have been described as pale cells in the literature. Intercalated clear cells appear mainly in non-ischemic nodal tissue. Pale cells are ischemically damaged sinus nodal cells.

Animals↗
PubMed2000

[Arthropathy in beta-thalassemia minor].

CASE REPORT: A 25-year-old Turkish patient presented with a "swelling" of the ankles which now persisted for 5 years. He had previously been diagnosed as having HLA-B27 negative spondylarthropathy with peripheral joint involvement. The symptoms failed to respond to different therapies. Serological markers and radiological procedures revealed beta-thalassemia minor. DISCUSSION: Symptoms, diagnostic procedures and differential diagnostic options are discussed.

Adult↗
PubMed2000

Marked genetic similarities between hepatitis B virus-positive and hepatitis C virus-positive hepatocellular carcinomas.

Hepatocellular carcinoma (HCC) is one of the most common neoplasms worldwide. Well-established risk factors include infections with two very different viruses: the DNA virus causing hepatitis B (HBV) and the RNA virus inducing hepatitis C (HCV). In order to determine whether genetic differences exist between HBV- and HCV-induced HCC, 41 HCC samples of known vival status were examined by comparative genomic hybridization (CGH). The analysis revealed frequent deletions of 1p (24%), 4q (39%), 6q (41%), 8p (44%), 9p (24%), 11q (24%), 12q (22%), and 13q (39%), as well as common gains of 1q (46%), 6p+ (20%), 8q+ (41%), 11q (27%), and 17q+ (37%). There was no significant difference in the number and type of chromosomal imbalances between 25 HCV- and 16 HBV-infected tumours. This is consistent with models suggesting that HBV and HCV cause cancer through non-specific inflammatory and regenerative processes, rather than through virus-specific interactions with defined target genes. Chromosomal imbalances were also unrelated to the grade and stage of HCC. This may suggest that most gross genomic alterations occur early during HCC development and that further progression of these tumours may be associated with other types of genetic changes, not detectable by CGH. In summary, these data show that characteristic gross genomic changes occur in HCC, but these alterations at present do not appear to have diagnostic or prognostic applications.

Adult↗
PubMed2000

[Not Available].

The investigation of Lenin's brain by the German neurobiologist Oskar Vogt from Berlin and his Russian collaborators in Moscow is one of the most exciting and simultaneously oddest chapters in the history of medicine. With the bizarre claim to be able to detect the material substrate of genius it provoked as much unrealistic expectations in the public as strong criticism by the scientific community of brain researchers. The present paper deals in a brief survey with the history of collecting and measuring the brains of famous persons in general and particularly with the historical, political and social circumstances of the performed investigation of Lenin's brain. In this connection the epistemological and technical prerequisites of architectonical brain research and its means of the topographical representation of complex histo-anatomical and physiological differences in the brain cortex are shortly discussed. The opening of Russian archives after the socio-economic turn of the year 1991 brought up new background facts in Lenin's pathobiography; together with the sources from German archives a rather extensive reconstruction of the historical events between Lenin's death in 1924 and the final report of the Moscow Brain Research Institute (Institute Mozga) to the Politburo of the Russian Communist Party (Bolsheviki) in 1936 is possible now.

Brain↗
PubMed2000

Temperament and character during the course of unipolar depression among inpatients.

Cloninger has developed a novel approach concerning relationships between psychopathological syndromes and personality by his biosocial theory. Increased levels of harm avoidance (HA) were consistently found in unipolar disorders. The present study was conducted to cross-validate, in part, previous findings that high harm avoidance (HA) persisted in the course of disorder and to explore the distinct role of character dimensions. One hundred and twenty-six inpatients with an unipolar depressive disorder and 126 healthy controls, strictly matched for age and gender have been included in the study. Our findings underline that higher harm avoidance among unipolar depressives compared to healthy controls persisted after treatment even if a significant reduction could be observed. Recurrent disorders and comorbidity with anxiety disorders seem to be related to a relatively immature character in terms of consistently lower scores for the character dimensions (e.g. self-directedness and cooperativeness) of the patients classified into these groups both at admission and at discharge compared with their healthy counterparts.

Adult↗
PubMed2000

[Optimized 3-D planning by simple means. An example].

AIM: A treatment technique favorable for linacs with asymmetric jaws, which combines cranio-caudal matching fields with fields enclosing the whole target volume, is investigated with respect to field matching and sparing of normal tissue and organs at risk. PATIENT AND METHODS: For a pelvic target volume rapidly varying in cranio-caudal direction a 5-field technique was planned with individually weighted and blocked fields. Three fields adjoining in cranio-caudal direction were completed by 2 fields enclosing the whole target volume. The matching line was measured and calculated with Helax TMS. Furthermore a 4-field box and opposing fields were planned. The dose-volume histograms for target, bladder, intestine and soft tissue were exported. Normal tissue complication probability and tumor control probability, respectively, were calculated for all techniques. RESULTS: In the region of the matching line the summation of the measured normalized curves resulted in relative dose maxima of 6.0% (caudal) and 4.5% (cranial), respectively. For fields enclosing the whole target volume the dose maxima in the region of the matching line decreased to 2.0% (caudal) and 1.8% (cranial), respectively. For the dose profiles calculated with Helax TMS no overdose was found. The 5-field technique with adjoining fields results in a better sparing of the organs at risk compared to the other techniques, whereas the tumor control remains the same. CONCLUSIONS: In specific cases a technique with cranio-caudal adjoining fields can be recommended with respect to sparing of normal tissue and organs at risk.

Humans↗