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Biomedical subjects

J Volmer

Publications and source records attributed to J Volmer.

At least 19 recordsLinked to original sources
PubMed2006

Determination of the pion charge form factor at Q2=1.60 and 2.45 (GeV/c)2.

The 1H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F(pi)) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which F(pi) is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative quantum chromodynamics prediction.

Journal Article↗
PubMed2001

Longitudinal electroproduction of charged pions from (1)H, (2)H, and (3)He.

Separated longitudinal and transverse cross sections for charged pion electroproduction from (1)H, (2)H, and (3)He were measured at Q(2) = 0.4 (GeV/c)(2) for two values of the invariant mass, W = 1.15 GeV and W = 1.60 GeV, in a search for a mass dependence which would signal the effect of nuclear pions. This is the first such study that includes recoil momenta significantly above the Fermi surface. The longitudinal cross section, if dominated by the pion-pole process, should be sensitive to nuclear pion currents. Comparisons of the longitudinal cross section target ratios to a quasifree calculation reveal a significant suppression in (3)He at W = 1.60 GeV. The W = 1.15 GeV results are consistent with simple estimates of the effect of nuclear pion currents, but are also consistent with pure quasifree production.

Journal Article↗
PubMed2001

Measurement of the charged pion electromagnetic form factor.

Separated longitudinal and transverse structure functions for the reaction 1H(e,e(')pi(+))n were measured in the momentum transfer region Q2 = 0.6--1.6 (GeV/c)(2) at a value of the invariant mass W = 1.95 GeV. New values for the pion charge form factor were extracted from the longitudinal cross section by using a recently developed Regge model. The results indicate that the pion form factor in this region is larger than previously assumed and is consistent with a monopole parametrization fitted to very low Q2 elastic data.

Journal Article↗
PubMed1986

[Malignant clear cell hidradenoma of the external auditory canal].

A patient with a clear cell (malignant) hidradenoma of the external auditory canal and a detailed review of the literature are presented. Tumours of the ceruminous glands are rare. A sub-classification into distinct histological tumour types is useful with respect to therapy and prognosis. About two-thirds of all these neoplasms are malignant and the frequency of recurrence is very high (50%). Most of the adenomas are not encapsulated. The well differentiated adenocarcinomas (low grade malignancy) of the ceruminous glands can only be distinguished histologically from adenomas by their tendency to invade and infiltrate. Therapy of the ceruminous adenomas is wide excision; the treatment of carcinoma is radical block resection.

Adenoma, Sweat Gland↗
PubMed1986

[Coincidence of liver cirrhosis and gallstones].

In the years 1957-1975 we found out of 13336 autopsies in a medium-sized urban general hospital 912 cases of cirrhosis of the liver. In comparison these persons with sections of non-cirrhotic controls the frequency of gallstones was neither for the total group (33.9%) nor for the males (27.1%) significantly raised. Only in the female subgroup of cirrhotic patients we could demonstrate a significantly increased frequency of gallstones (43.5%) in comparison to the female control group (38.3%). With regards to all kinds of predominantly lithogenous alterations of the gallbladder (concrements, chronic cholecystitis, cholecystectomy) we found for the cirrhotic group and its subgroups a significant positive coincidence of both diseases. The female to male ratio for the frequency of cholelithiasis and for all kinds of lithogenous alterations of the gallbladder was 1.6:1 for the cirrhotic group and the controls.

Aged↗
PubMed1985

[Malignant fibrous histiocytoma of the larynx].

Report on two patients with (malignant) fibrous histiocytomas of the larynx. Fibrous histiocytomas of the larynx, malignant or benign are extremely rare. Because of the variety of the tissue the histiological diagnosis of these tumours--especially with regard to the tumour status--can cause great difficulties. Basing on our cases and on the few previous publications on this subject, the biological behaviour and therapy of laryngeal histiocytomas, as well as differential diagnoses of other neoplasms, are discussed. Since the (malignant) fibrous histiocytomas often recur locally, even tumours without unequivocal histological malignancy must be treated by extensive excision.

Adult↗
PubMed1985

Semiquantitative and morphometric investigations on the histopathology of chronic hepatitis non-A, non-B.

Ninety-five cases (202 liver biopsies) with chronic hepatitis Non-A, Non-B (NANB) were investigated histologically. The alterations were analysed semiquantitatively. The histological indices (e. g. volume of the portal tracts, number of acidophilic bodies) of various case groups of chronic hepatitis NANB were determined morphometrically and the results were checked for internal statistical significance and for correlations with comparison groups of chronic hepatitis B. The large number of acidophilic bodies and sinusoidal cells are the sole characteristic histological sign of hepatitis NANB which enable its differential diagnosis, especially from hepatitis B. The chronic post-transfusion hepatitis NANB has a relatively good prognosis and in 80% of the cases shows the course of a chronic persistent hepatitis (CPH). In sporadic hepatitis NANB a chronic aggressive hepatitis (CAH) is present in 60%. The frequency of cirrhosis based on an already chronic stage is 12.6%. An indication for immunosuppressive therapy of sporadic chronic aggressive hepatitis NANB can only be established individually after a sufficiently long observation of the biochemical and histological alterations.

Biopsy↗
PubMed1984

[Intraductal (intracystic) papilloma of the male breast].

Report on a case of a 26-year-old man with an intraductal papilloma of the brast developed on a preexisting gynecomastia. Simultaneously the patient is suffering from a tumor of the pituitary gland with signs of acromegaly and pathologically increased serum concentrations of STH and ACTH. The possibility that the pituitary gland tumor has indirectly induced the intraductal papilloma by hormonal stimulation is discussed.

Adult↗
PubMed1983

[Pseudoplasmacytoma of the uterine cervix].

Report on a case of a 21 year old woman with a pseudoplasmocytoma of the cervix of the uterus. A tumour-like proliferation of plasma cells had developed in the area of a glandular ectopia of the cervix mucosa with a secondary erosion, which stretched continuously into the myometrium. The morphological changes were difficult to differentiate diagnostically from an extra-medullary plasmocytoma. After taking into account all histological and clinical data as well as the progression of the disease, the lesion was interpreted to be a well defined tumour-like reactive plasmocytosis of the cervix of the uterus.

Abortion, Spontaneous↗
PubMed1983

[A case of bleeding angiodysplasia of the colon].

Report on a patient with bleeding angiodysplasia of the ascending colon. The clinical course was characteristic for this kind of lesions: long-term, chronic, recurrent intestinal hemorrhages with a gradual increase of anemia. Diagnosis was complicated by lack of success in finding the source of the hemorrhage and by evidence of various pathological findings. Histologically, there were vessel variations typical for angiodysplasia and, furthermore, cholesterol emboli of the submucosal colic arteries. The latter's pathogenetic role as trigger for the hemorrhage is discussed.

Aged↗
PubMed1982

The effectivity of immunosuppressive therapy on chronic aggressive (active) hepatitis and on chronic nonsuppurative destructive cholangitis (PBC). Morphometric investigations on the portal tracts of the liver.

Morphometric investigations were carried out on liver biopsies of chronic aggressive (active) hepatitis (CAH), type IIa, chronic aggressive (active) hepatitis, type IIb, and on chronic nonsuppurative destructive cholangitis (CNDC) (primary biliary cirrhosis (PBC) in the second and third stages. The goal of the histometric analysis was a comparison of the portal tracts before and after immunosuppressive therapy with azathioprine and corticosteroids as well as with azathioprine alone. The volume and surface measurements of the portal tracts and their components showed that for an evaluation of the effectivity of the immunosuppressive therapy on CAH, along with a division into HBsAg-positive and -negative cases, a histologically determined degree of the severity of the inflammatory activity is extremely significant. The therapeutic effect is significant for all cases of CAH IIb, evident for HBsAg-negative cases of CAH IIa and slight for HBsAg-positive cases of CAH IIa. Immunosuppressive therapy of CNDC has no effect on the characteristic destruction process of the bile ducts and ductule proliferation.

Azathioprine↗
PubMed1981

Morphometric investigations on the portal tracts of the liver, the differentiation of variable progression in chronic persistent hepatitis.

Morphometric investigations were carried out on the portal tracts of the liver in different forms of chronic hepatitis. The investigation groups each contained 25 liver biopsies, which were subdivided into cases with normal liver, a subsiding acute virus hepatitis, three different forms of chronic persistent hepatitis (CPH) and chronic aggressive hepatitis type IIa (CAH IIa). Determinations of the volume and surface of the portal tracts and their components enabled three forms of COH (type Ia, Ib, Ic) to be characterised. Preliminary clinical and semiquantitative histological investigations were correlated with a significant difference in the histological characteristics and prognosis. HBsAg-positive and HBsAg-negative cases showed no significant morphologically detectable differences in all grups investigated. Morphometry is suitable for investigation of pathological changes in liver tissue, especially the portal tracts.

Adult↗
PubMed1980

Vascular tumors in the region of the breast.

Three vascular tumors in the breast region with different degrees of differentiation are presented. The first neoplasm is a haemangiosarcoma (of the vascular neoplasms, these tumors are the type which occur most frequently in the breast). Haemangiosarcomas show an infiltrative growth of atypical blood capillaries, frequently with formation of highly cellular and solid capillary sprouts. Ultrastructurally, the tumor cells are characterized as endothelial, also in the region of the capillary sprouts. The second tumor (an angiosarcoma in Stewart-Treves-syndrome, STS) is characterized by an intensive endothelial proliferation. Solid spindle-celled regions are also found in which the tumor cells correspond to undifferentiated mesenchymal cells, but other cells possessing properties of smooth muscle cells and pericytes may be found. The third tumor corresponds light and electron microscopically to a haemangiopericytoma of the soft tissue. The pericytic character of the tumor cells is most clearly seen in the immediate vicinity of the vessels. With increasing distance from the capillaries, the tumor cells take on the characteristics of fibroblasts. The tumors reflect the diversity of the angioplastic differentiation potential of the mesenchyme.

Adult↗
PubMed1979

[Chronic persistent hepatitis. Histological and clinical study of different forms of the course of CPH].

Among 4903 liver biopsies were found 96 cases (241 biopsies) of non-active hepatitis persisting for longer than one year (up to 12 years). Three forms of the course of chronic persistent hepatitis could be delimited in morphological terms taking into account clinical laparoscopic and clinical chemical data. The type Ia presents the picture of a largely subsided, lobular accentuated acute virus hepatitis. The type Ib corresponds to a chronic inflammation with emphasis on the portal system without destruction of the limiting plate, without fibrosis and with only slight intralobular involvement. The type Ic is characterized by a portal and slight septal fibrosis with round-cell infiltrates and a slight facultative periportally active inflammation as well as a moderate intralobular mesenchyme reaction. The typing permits a clear subdivision and a differentiated prognosis: 10% of the cases of type Ic pass into an active chronic hepatitis of the type IIa.

Adult↗
PubMed1979

[A tapeworm infection with fatal outcome (author's transl)].

Parasitoses of the intestinal tract are rare in Europe. Their diagnosis is difficult since the general symptoms are frequently only little pronounced or completely lacking. On the other hand, the course of the disease may be fatal. Such cases from the literature and our own observations are intended to call to memory the differential diagnosis of intestinal parasitosis.

Aged↗