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Biomedical subjects

K Dietz

Publications and source records attributed to K Dietz.

At least 19 recordsLinked to original sources

[Quantitative analysis of recurrence and spontaneous regression of basalioma parts left in situ].

To some extent, parts of basalomas found remaining in situ following tumour excision tend to spontaneous regression. This is a well-known phenomenon and has significance for the recurrence of incompletely excised tumors. The present study involved a quantitative investigation of the relationship between recurrence and spontaneous regression. Following precisely defined excision of basalomas, the entire exterior of the excised material was examined by contrast microscopy in HE-stained paraffin sections (3-dimensional histology). Whenever tumour outgrowths were found, it was possible to document exactly their type, localization, extent, and depth of invasion. In 66 such cases no follow-up operation was performed, but only a follow-up examination after a minimum of 31 and a maximum of 113 months (average: 60 months). Only 50% of these undisturbed tumour outgrowths resulted in a recurrence during the follow-up period. A very high rate of spontaneous regression (71%) was found among the solid tumour outgrowths, but a significantly lower rate (19%) among the fibrosing tumours. Moreover, regression was dependent on the tumour remnant's mass and the clinical diameter of the tumour removed. It was independent of the depth of infiltration. Although the rate of spontaneous regression of tumour outgrowths persisting after therapy is relatively high, it cannot be predicted in individual cases. It is not possible to be certain that tumour removal has been achieved unless micrographic surgery has been continued until complete absence of tumour is proved. In all procedures that are not subsequently monitored, an unacceptably high rate of recurrence must be expected, especially in the case of fibrosing basaloma. This is commented on at length.

Aged

[Extrahepatic bile duct atresia. Comparison of surgical and non-surgical therapy].

In recent years hepatoportoenterostomy according to Kasai undoubtedly was the only successful therapy for extrahepatic biliary atresia. Since liver-transplantation becomes more successful than previously, the question arises if the Kasai procedure is still justified. From this point of view a prospective study was started based on the following findings in 15 EHBA-children after hepatoportoenterostomy compared to those in 15 patients without the Kasai procedure: the survival rate at the end of two years of life; the development of ascites until the end of the first year of life; the weight and length percentiles at the end of the first year of life; and the activity of serum cholinesterase. In order to calculate significant differences in weight and length percentiles, the exact Fisher test was used. Serum cholinesterase activities of both the above mentioned groups were compared with each other, as well as with the normal values of a third group of 50 healthy children, by analyzing variances and then comparing one by one with adjustment for multiple comparisons. There was a significant difference between the operated and not-operated group, and in addition between the non-operated and the healthy group. In contrast, no significant difference was detected between the operated and the healthy group. These differences were best demonstrated by the findings of weight and length percentiles and the activity of serum cholinesterase. From this we conclude sofar hepatoportoenterostomy undoubtedly is standard procedure in the treatment of EHGA. However, if the Kasai procedure fails or the liver disease progresses to a greater extent, liver transplantation will become the method of choice.

Biliary Atresia

[Statistical approach to forensic conversion values for alcoholics].

With collaboration of the study groups from Tübingen, Munich and Kiel and consideration of the results of Bonnichsen et al 1968, alcohol elimination curves of 98 alcoholics were subjected to a joint evaluation for determination of the beta 60 values. The average elimination rate was 0.21 g/kg/h (s = 0.05 g/kg/h). By analogy to average beta 60 values and back-conversion factors of nonalcoholics, the limit values for alcoholics were estimated as being between 0.12 g/kg/h (minimum value) and 0.29 g/kg/h (maximum value).

Adult

Seroepidemiological correlations of antibodies to human herpesviruses and human immunodeficiency virus type 1 in African patients.

A seroepidemiological evaluation of the humoral immune response against human herpes viruses was carried out in patients with and without HIV infection in Tanzania to study the role of these viruses as a cofactor in AIDS. Serum specimens were obtained from 321 outpatients and 100 healthy schoolchildren of a rural population in the Kagera Region, Tanzania, and from 149 inpatients of an urban population in Dar-es-Salaam, Tanzania. The data were analysed by logistic models taking into account demographic variables. The data obtained revealed no differences in the prevalence of antibodies to human herpes viruses between the different groups. Therefore, our study under the present conditions and the observed stages of AIDS does not suggest an influence of HIV infection on human herpesvirus infection or serologic response.

Acquired Immunodeficiency Syndrome

Prediction of subclinical tumor infiltration in basal cell carcinoma.

Two thousand-sixteen basal cell carcinomas (BCCs) were documented in terms of age, anatomic location, tumor diameter, initial excision depth, safety margin, histologic type, and the position of tumor outgrowths as determined by three-dimensional histologic study of the tumor margins in paraffin sections (micrographic surgery). The extent of each subsequent excision was recorded until tumor-free tissue was reached. The results showed that BCCs have a highly irregular infiltration pattern and a predilection for small, fingerlike outgrowths whose bases occupy 1-30 degrees of the tumor circumference. When superficial extension was expressed mathematically, the resulting exponential functions varied highly significantly (P = .001) according to histologic tumor type and diameter. The resulting curves permitted very precise prediction of the probability of tumor-positive margins (ie, subtotal excision), depending on the safety margin, histologic tumor type, and tumor diameter. For example, the probability of tumor-positive margins after excision of a BCC up to 10 mm in diameter is 30% with a safety margin of 2 mm, 16% with a safety margin of 3 mm, and 5% with a safety margin of 5 mm. The probability of tumor-positive margins for fibrosing primary BCCs 10-20 mm in diameter is 48, 34, and 18% with safety margins of 2, 3, and 5 mm, respectively. Recurrent tumors have a significantly higher probability of positive margins (P = .001) than primary ones. Anatomic location and tumor age affect subclinical extension only indirectly.

Basal Cell Carcinoma

Mathematical models of myosin heterodimer formation in the rat heart during thyroid hormone alterations.

To characterize the mechanisms involved in the formation of the myosin heavy chain (MHC) heterodimer V2 (alpha beta-MHC) and the homodimers V3 (beta beta-MHC) and V1 (alpha alpha-MHC), 82 5-week-old normotensive rats with homogeneous V1 were made hypothyroid with propylthiouracil (0.8%, drinking water), and the proportion of V2, V3, and V1 was determined by pyrophosphate gel electrophoresis in multicellular specimens of the left and right ventricles. After the switch from alpha-MHC to beta-MHC, the beta-MHC occurred initially in the form of the heterodimer. After 4 and 6 days, V2 was greater (p less than 0.05) than V3. At day 8, V2 was smaller than V3, and at day 10, V2 was not statistically different from V3. From day 12 onward, V2 was smaller than V3. After 21 days, the propylthiouracil treatment was stopped, and the remaining 34 hypothyroid rats were injected with a daily dose of thyroxine (average, 0.1 mg/kg body wt), resulting in a switch from beta-MHC to alpha-MHC. After 1 day, V2 still was greater than V1; however, already from day 3 onward, V2 was smaller than V1. This characteristic but unexplained heterodimeric and homodimeric organization of the thick filament was analyzed by mathematical models involving probability calculations. Two principally different models were established that assume either the exchange of MHC dimers or of single MHC in the thick filament. The parameters of the models were estimated by minimization routines using the squared discrepancies between the experimental and predicted isoenzyme populations. Based on goodness of fit and crucial model parameters, we concluded that the characteristic organization of the thick filament can be accounted for by an exchange involving predominantly MHC dimers and not single MHC. The fact that V2 was lower than expected if formation of heterodimers and homodimers were random was attributed to the preferred homodimerization of 35% of the newly synthesized MHC.

Animals

[Locally infiltrative growth of squamous cell carcinoma of the skin and treatment guidelines resulting from it].

The infiltrative growth behaviour of squamous cell of the skin carcinomas is characterized by subclinical outgrowths, very frequently extending horizontally and sometimes over long distances. They are presented in the form of a negative exponential function. These outgrowths have an irregular pattern. It is much more extensive in the case of tumours with a clinical diameter of more than 20 nm. All types of "blind" therapy such as cryopexy, irradiation, laser, and surgery monitored in only two dimensions involve an inevitable risk of recurrences, which can be calculated statistically from the results available. Routine histographical surgery of skin carcinomas in the form of continuous, 3-dimensional histology can dramatically reduce the risk of local relapse, especially in the case of small and medium-sized carcinomas. The test group presented here (411 carcinomas) was treated with histographic surgery using the paraffin section method; during the follow-up period (maximum: 7 years, minimum: 3 years) the danger of recurrence was 2.2% for all carcinomas but only 0.6% for those up to 20 mm in diameter (n = 340). Carcinomas with a diameter of more than 20 mm (n = 71) involved a much higher risk of recurrence with 9.8%. This is probably because of local micrometastases, which require more generous local excision with a safety margin of about 10 mm.

Carcinoma, Squamous Cell

[The subclinical portion in the periphery of lentigo maligna and lentigo maligna melanoma].

Lentigo maligna is a precancerosis or a melanoma in situ, whose level of malignancy has not yet been definitively clarified. Recurrences are not rare after excision, even when an ample safe margin is observed. One reason for this is the existence of a subclinical ramification in the marginal area of the lentigo maligna. Such subclinical ramifications were investigated by means of excision with histological monitoring of the margins by the paraffin section technique. There was a clear relationship between the frequency of these ramifications and the clinical safe margin left in 64 excisions. With the aid of parametric evaluation methods the distribution of the subclinical portion referred to the distance from the clinical margin could be determined with a special formula. If an invasion, in the form of a lentigo maligna melanoma had already taken place, then the subclinical portion within the marginal area was significantly more extensive. For the treatment of lentigo maligna, and especially of lentigo maligna melanoma, we therefore recommend excision with histological monitoring of the margins. There were no local recurrences within an average follow-up period of about 2 1/2 years.

Adult

Evaluation of seroepidemiological associations between HIV-infection, hepatitis B and other sexually transmitted diseases in African patients.

To assess the possible role of sexually transmitted diseases as cofactors for the spread of AIDS, 248 adult patients were tested for the presence of antibodies against human immunodeficiency virus (HIV), hepatitis B virus (HBV) and syphilis. The survey was conducted in a hospital at Kagondo, Kagera Region, Northwest Tanzania, Africa. Subjects were randomly chosen from the outpatient clinic to include those with and without sexually transmitted diseases, as well as AIDS/pre-AIDS patients. The data were univariately and multivariately analysed by linear logit models, including interactions of demographic parameters. The results obtained reveal a strong association between the presence of antibodies against HIV, syphilis and HBV, respectively. The HBV/HIV-correlation remained stable in the multivariate analysis including interactions of social parameters, in contrast to the syphilis/HIV-correlation. We assume that this reflects the lower virulence of HBV as compared to that of syphilis. The prevalence of anti-HBV antibodies seems to be a more reliable marker for high sexual activity than those against syphilis. The possibility that HBV and HIV act as cofactors for each other's transmission could not be ruled out.

Acquired Immunodeficiency Syndrome

Infection with human T-cell leukemia virus type I in patients with leukemia.

Among 211 adults with leukemia who received multiple transfusions, 6 were found to be seropositive for human T-cell leukemia virus Type I (HTLV-I). Before the positive serum specimens were obtained, these patients received a mean of 14 units of red cells and 78 units of platelets. Seroconversion could be documented in three patients. None of the 6 patients seropositive for HTLV-I had a T-cell leukemia, other illnesses attributable to HTLV-I infection, or risk factors for HTLV-I infection other than transfusion: none were seropositive for human immunodeficiency virus. Patients with leukemia who receive multiple transfusions appear to be at risk for HTLV-I infection.

Antibodies, Viral

Epidemiological models for sexually transmitted diseases.

The classical models for sexually transmitted infections assume homogeneous mixing either between all males and females or between certain subgroups of males and females with heterogeneous contact rates. This implies that everybody is all the time at risk of acquiring an infection. These models ignore the fact that the formation of a pair of two susceptibles renders them in a sense temporarily immune to infection as long as the partners do not separate and have no contacts with other partners. The present paper takes into account the phenomenon of pair formation by introducing explicitly a pairing rate and a separation rate. The infection transmission dynamics depends on the contact rate within a pair and the duration of a partnership. It turns out that endemic equilibria can only exist if the separation rate is sufficiently large in order to ensure the necessary number of sexual partners. The classical models are recovered if one lets the separation rate tend to infinity.

Epidemiologic Methods

Emergence of Onchocerca volvulus microfilariae from skin snips before and after treatment of patients with ivermectin.

As ivermectin is supposed to have a paralyzing effect, the emergence of Onchocerca volvulus microfilariae from skin snips before and after treatment was examined. Before treatment 79.8% of the microfilariae emerged from the skin snips. Three days after treatment the microfilarial skin density had dropped to 83% (placebo), 28% (100 microgram/kg ivermectin), 19% (150 micrograms/kg) and 14% (200 micrograms/kg) of the pretreatment values but the microfilarial emergence was not altered distinctly. The majority of the remaining microfilariae were mobile and able to leave the biopsy. Only a slight, but significant, dose-dependent trend of reduced emergence could be shown. From our results no direct support is derived for the hypothesis that O. volvulus microfilariae are paralyzed or immobilized by ivermectin.

Analysis of Variance

Human immunodeficiency virus infection in patients with leukemia.

Eighteen human immunodeficiency virus (HIV)-seropositive patients were found among 211 previously treated adult patients with a variety of leukemias who had been multiply transfused before April 1985. Patients known to be homosexual or intravenous drug users were excluded from this study. The spouse of one HIV-seropositive patient became HIV infected and subsequently developed the acquired immune deficiency syndrome. Patients with leukemia who were multiply transfused before the availability of screening of blood products for HIV antibody should be counseled regarding their individual risks of HIV infection and the risk to sexual contacts.

Female

Common respiratory and gastrointestinal illness in paediatric student nurses and medical technology students.

The aim of this study was to establish the risk of acquiring common respiratory and gastrointestinal illness for paediatric nurses. Using self-administered questionnaires, student nurses at two children's hospitals and students at one school of medical technology reported biweekly the number of minor illnesses, symptoms, and indicators of severity of infection over a 3-year period (1975-8). Although a systematic bias was evident with some symptoms, others appeared to be quite reliable. The following four syndromes were defined to estimate the risk: upper respiratory syndrome (URS), lower respiratory syndrome (LRS), respiratory and gastrointestinal syndrome (RGS), and gastrointestinal syndrome (GS). Surveillance days were allocated to groups with high- or low-intensity contact with children. The incidence of all illnesses was 2.9 per person-year in the low-intensity contact group and 4.4 per person-year in the high-intensity contact group. The reported incidence of LRS and RGS in the high-intensity contact group was 1.55 times higher than in the low-intensity group (P less than 0.001). LRS and RGS incidence was similar in nurses at both schools. During low contact periods it corresponded to that of the medical technologists.

Adolescent