A high-field superferric NMR magnet

Strong, extensive magnetic fringe fields are a significant problem with magnetic resonance imaging magnets. This is particularly acute with 4-T, whole-body research magnets. To date this problem has been addressed by restricting an extensive zone around the unshielded magnet or by placing external unsaturated iron shielding around the magnet. This paper describes a solution to this problem which uses superconducting coils closely integrated with fully saturated iron elements. A 4-T, 30-cm-bore prototype, based on this design principle, was built and tested. The 5 G fringe field is contained within 1 meter of the magnet bore along the z axis. Homogeneity of the raw magnetic field is 10 ppm over 30% of the magnet's diameter after passive shimming. Compared with an unshielded magnet, 20% less superconductor is required to generate the magnetic field. Images and spectra are presented to demonstrate the magnet's viability for magnetic resonance imaging and spectroscopy.

[A clinical evaluation of MAb BW 835/6 in breast and ovarian cancer]

Studies with the 99mTc-labeled murine monoclonal antibody BW 835/6 in patients suspected of breast (n = 7) or ovarian cancer (n = 8) showed insufficient depiction of primary tumors and metastases of breast cancer, but promising results in the detection of primary tumors in ovarian cancer without metastases. The small number of patients does not allow statistical analysis.

[Results of treatment in vulvar cancer from 1970 to 1990]

From 1970-1990, 159 patients with invasive malignant tumours of the vulva (150 squamous cell carcinomas) underwent surgery at the University Hospitals, department of gynaecology. Heidelberg (1970-1988) and Homburg/Saar (1988-1990). 73% of the patients were more than 60 years old and 3% were less than 40 years old. The mean age was 69 years. 30% of the patients had diabetes mellitus. As a standard therapy, 101 patients had radical vulvectomy with bilateral inguinal node removal in accordance with S. Way. If nodes were found to be positive, the inguinal/pelvic region was irradiated postsurgically with 40-50 Gy. The 5 years survival rate for all patients with vulvar carcinoma was 69%. For early stage carcinomas (pT1, depth of invasion < or = 1 mm) a restricted radical therapy should be considered. 9 patients with early stage carcinomas survived disease-free for a period of 70 months. Significant prognostic differences were noticed if node histology was N- as opposed to N+ (p < 0.001), if depth of invasion was < or = 1 mm as opposed to > 10 mm (p < 0.001), if stage was pT1 as opposed to pT2 to pT4 (p < 0.001) or if lymphangiosis carcinomatosa (p < 0.01) was present or not. Prognostic differences were also noticed, if cytological grading was done in accordance with Broders (p < 0.09). 27 patients had successful reconstructive surgery with local cutaneous or myocutaneous flaps at the time of initial surgery. The median recovery period after radical vulvectomy with bilateral inguinal lymph node excision was 22 days. The median recovery period after radical vulvectomy with bilateral node removal and reconstructive surgery was 25 days. Early recurrence of carcinoma (< or = 6 months after initial therapy) was 5.9%, late recurrence was 12%.

[Use of computer-assisted image analysis for the detection of immunohistochemical receptor status in breast cancer. Immunohistochemical densitometry receptor analysis--IRDA]

A method for the evaluation of the immunohistochemical staining score of steroid receptors in breast cancer using computer-based image analysis is presented. The optical density of tumour cell nuclei was measured using kryostat sections and, using a control section as reference, an objective threshold for specific staining was defined. In intensively stained sections, a good correlation with visual scoring was achieved, but in 9 out of 16 sections, which were regarded as receptor-negative by visual scoring, a specific receptor-positive staining was demonstrated by image analysis. Next to the percentage of positive cells (PP) and the mean staining intensity (SI), a histogram of the receptor concentration in positive nuclei was calculated. The method allows, besides an objective evaluation and documentation, an exact definition of a threshold for specific receptor measurement and furthermore shows the pattern of receptor concentration in the tumour cell nuclei. Hence, the method could contribute towards a more widespread use of immunohistochemical receptor analysis.

Age-related changes in kynurenic acid production in rat brain

Two separate in vitro assays were used to examine the biosynthesis of the broad spectrum excitatory amino acid receptor antagonist kynurenic acid (KYNA) during the life span of the adult rat. Assessment of KYNA's anabolic enzyme kynurenine aminotransferase revealed steady increases between 3 and 24 months of age in all five brain regions examined. No changes were observed in the liver. The changes were particularly pronounced in the cortex and in the striatum where enzyme activity increased three-fold during the period studied. KYNA production from its bioprecursor L-kynurenine was also investigated in tissue slices and was found to be significantly enhanced in the cortex and hippocampus of old animals. The effect of depolarizing agents or sodium replacement was virtually identical in tissues from young and old rats. These data, which are in excellent agreement with reports on an age-dependent increase of KYNA concentration in brain tissue, suggest an enhanced KYNA tone in the aged brain. Together with the reported decline in cerebral excitatory amino acid receptor densities with age, increased production of KYNA may play a role in cognitive and memory dysfunction in old animals.

[Recurrence of vulvar cancer--treatment, experiences and results]

At the University Hospitals of Heidelberg (1970-1988) and Homburg/Saar (1988-1990), 182 patients with vulvar carcinoma were treated. 51 patients had a recurrence of vulvar carcinoma and 21 patients showed a persistence of this tumour. 19 women had a second recurrence of vulvar disease. In these cases, therapy ranged from local surgery to exenteration, depending on the site and tumour extension. 18 patients underwent successful reconstructive surgery. Prognosis was better in cases with local recurrence in comparison to distant sites of metastatic progression (i.e. inguinal nodes or disseminated disease) (p less than 0.001). The five-year survival (after diagnosis of recurrent disease) for patients with early onset of recurrence (less than 20 months after initial therapy) was 28% compared to 68% for patients with late onset of recurrent disease (p less than 0.01).

Localization of kynurenine aminotransferase immunoreactivity in the rat hippocampus

The localization and distribution of kynurenine aminotransferase (KAT), the biosynthetic enzyme of the excitatory amino acid receptor antagonist, kynurenic acid, was studied in the rat hippocampal formation with immunohistochemical methods. The enzyme was found mainly in glial cells that could be distinguished as 3 types on the basis of their shapes and locations. Typically, these cells shared the morphological features of astrocytes and exhibited glial fibrillary acidic protein immunoreactivity as demonstrated by a double-labeling technique. The distribution of KAT-containing glial cells was heterogeneous throughout the hippocampal formation. In the hippocampus, the stratum lacunosum-moleculare of Ammon's horn and the hilus contained a higher density of KAT-positive glial cells than other regions, whereas the lowest density of KAT glial cells was observed in the granule cell layer of the dentate gyrus and in the stratum radiatum of CA subfields. In the subicular complex, the density of KAT-containing glial cells was generally higher in the superficial than in the deep layer. Hippocampal neurons exhibiting KAT immunoreactivity, distinguished as nonpyramidal cells, were very few in number and mainly distributed in strata oriens and pyramidale of Ammon's horn. Substantially more KAT-positive neurons were observed in layers II and III of the subicular complex. The organization of cellular elements containing KAT may be of relevance for the function and possible dysfunction of kynurenic acid in the rat hippocampal formation.

Pentylenetetrazol kindling and factors of glutamate transmitter metabolism in rat hippocampus

Male Wistar rats administered repetitively with pentylenetetrazol developed a dose-dependent enhancement of seizure behaviour referred to as pentylenetetrazol kindling. After a daily dose of 40 mg pentylenetetrazol/kg or physiological saline (control rats) injected intraperitoneally for a period of two weeks, hippocampal tissue was studied autoradiographically for high-affinity uptake of [3H]glutamate and, by activity staining, for aspartate aminotransferase and glutamate dehydrogenase. Most prominent changes were found in neuropil areas known to be endowed with glutamatergic structures. The uptake capacity of glutamate decreased by 48% (maximum rate), whilst activities of aspartate aminotransferase and glutamate dehydrogenase elevated to 140 and 130%, respectively. Cytochrome c oxidase activity was found to be unaffected. The findings indicate an important role of factors of the glutamate metabolism in the kindling process with respect to the production, utilization, and availability of transmitter glutamate.

Bioavailability of vinpocetine and interference of the time of application with food intake

In a pilot study based on an open cross-over design involving four phases, the relative bioavailability of the eburnamenine derivative vinpocetine (CAS 42971-09-5) was investigated in 8 healthy volunteers in relation to different times of drug administration relative to food intake. The substance was applied orally as 10 mg film tablets. The areas under the plasma concentration-time curves (AUC) amounted to 27.3 +/- 18.1 ng.h/ml (fasting) and 42.8 +/- 27.4 up to 54.3 +/- 38.4 ng.h/ml (non-fasting, intake before and after meal, resp.). The relative bioavailability under non-fasting conditions was found to be approx. 60 to 100% higher than under fasting conditions.

[Noninvasive function tests in the evaluation of vascular reactivity in pregnancy and pregnancy-induced hypertension]

At present, there is an increasing discussion regarding the change of the prostacyclin/thromboxane ratio as an aetiological factor of pregnancy-induced hypertension (PIH). By means of videophotometric capillaroscopy in the capillaries of the nailfold, it is possible to visualise the resulting changes in the microcirculation. This method employs a special illumination microscope (magnification of the optical system x 560). Red blood cell velocity is measured under test conditions and microcirculatorical reaction capacity on ischaemic stress. Studies were conducted on healthy non-pregnant women and on healthy pregnant women as well as on patients suffering from pregnancy-induced hypertension. A markedly reduced velocity of red blood cells in patients with pregnancy-induced hypertension was seen as a sign of vasoconstriction, namely, 0.53 mm/sec. versus 0.74 mm/sec. Furthermore, these patients have a higher reactivity to ischaemic stress, probably also as a result of the already existing vasoconstriction; however, the duration of the hyperaemic phases is reduced in pregnancy-induced hypertension. By this method, an insight can be gained into microcirculation in pregnancy and in pregnancy-induced hypertension. In addition, as preliminary studies have already shown, the influence exercised by different medications on microcirculation can be assessed.

Simultaneous interferometric and polarimetric strain measurements on composites using a fiber-optic strain gauge

A fiber-optic Michelson interferometer is used for remote sensing of the bending-induced surface strain (up to 2500 microepsilon) of plates made from carbon-fiber composites. The double-polarization method is used for eliminating the ambiguity of fringe counting. Simultaneous measurement of the birefringencedependent phase offset yields an additional analog (polarimetric) signal, which allows for initialization of the incremental readout. The measured dependence of surface strain on plate bending agrees with the theoretically expected linear relationship, and it agrees with the gauge sensitivity published by Valis et al. [Proc. Soc. Photo-Opt. Instrum. Eng. 1170, 495 (1989)]. The observed hysteresis and temperature sensitivity are significantly smaller than the same effects in an electrical strain gauge.

[Experiences up to now with the ultrasound dissection instrument in gynecologic oncology]

The energy of high frequency ultrasound is used to disrupt cellular structures. Since the water content of each individual cell is of utmost importance for the physical destruction of the cell, there may be a tissue-selective effect in respect of tissues such as epithelium (high water content) and mesenchyma (low water content). The various therapeutic modalities are described in the following four cases. Ultrasonic tumor destruction was highly effective with regard to maximum reduction of tumor masses, especially for tumor sites which could not be removed by conventional tumor surgery. Blood vessels and nerves surrounded by tumor could be carefully and completely dissected--even in advanced stages. Peritoneal metastases from an ovarian carcinoma could be removed entirely, as well as the metastases within a tumor bulk (e.g. ureter within tumor mass); also the layers of tissue which were lost could be visualized again. So far, no increase in complications during and after surgery has been observed.

Pharmacokinetics of isometronidazole. Basic model and estimation of the kinetic parameters from experimental data

For the optimal timing of application of radiosensitizers in a course of radiotherapy it is important to know the sensitizer concentration at the time of irradiation. We have studied the pharmacokinetics of the hypoxic cell sensitizer isometronidazole in man and mouse and analyzed the data on the basis of an open two-compartment model after extravasal application. The parameter estimation is performed directly to avoid estimation biasing and data points from blood and tissue compartments are approximated simultaneously. The values obtained differ significantly from the estimations calculated by other authors for the same data.

Radioiodination of S-type lipopolysaccharide. Possibilities and limitations of labelling of the carbohydrate chain by periodate oxidation

S-type Lipopolysaccharide (LPS) from E. coli O 139:K 82 (B) was radiolabelled by coupling 125I-tyramine to the carbohydrate chain of LPS after oxidation of sugar residues carrying vicinal hydroxy groups, with sodium metaperiodate. The specific activity amounted to 1.3 kBq/microgram LPS. As LPS is a mixture of molecules with different carbohydrate chain lengths that are associated to large micelles of high kinetic stability, the preparation and the properties of the tracer exhibit some peculiarities. Most important, partial cleavage of the carbohydrate chains of LPS is caused on radioiodination by the procedure described. As a consequence, the tracer differs markedly from the starting LPS with respect to carbohydrate chain length distribution. Another feature of special interest is the variation of the specific activity (radioactivity/unit mass) for LPS molecules of different carbohydrate chain lengths. Because of the kinetic stability of LPS micelles, the equilibration of radioiodinated and non-radioactive LPS aggregates requires their solubilization by a detergent and its subsequent removal by dialysis. It could be demonstrated that short-chain LPS molecules predominantly associate to larger micelles than long-chain molecules. Regardless of these restrictions, the 125I-LPS proved to be useful for certain analytical purposes.

Klinische Prüfung mit MAk BW 835/6 bei Mamma und Ovarialkarzinomen

Untersuchungen mit dem 99mTc-markierten murinen monoklonalen Antikörper BW 835/6 an Patientinnen mit Verdacht auf ein Mamma- (n = 7) oder Ovarialkarzinom (n = 8) zeigten eine unzureichende Darstellung von Primärtumoren und Metastasen des Mammakarzinoms, aber eine erfolgversprechende Darstellung von Primärtumoren des Ovarialkarzinoms mit Ausnahme der Metastasen. Die geringe Fallzahl der Patientinnen läßt keine statistischen Aussagen zu.

Scotopic versus photopic pattern onset-offset electroretinograms

We investigated the contribution of rods and cones to the human pattern electroretinogram to onset and offset checkerboards of different spatial frequency and wavelength in a 39 degrees x 39 degrees field. Under strictly scotopic conditions, there was a negative potential at onset and a positive potential at offset, whereas under photopic conditions, there was a positive potential at onset and a negative/positive potential at offset. Thus, the waveform to pattern onset (offset) was that of the luminance electroretinogram to decreasing (increasing) luminances. For pattern onset, the sensitivity difference 486-601 nm under scotopic and photopic conditions closely followed the luminosity function of rods and cones. The amplitude of the scotopic onset response increased with check size up to 3 degrees 30' and that of the photopic onset response, up to 30'. With larger checks, the scotopic and photopic onset response markedly decreased. This indicates antagonistic center-surround organization of the receptive fields under both scotopic and photopic conditions. By contrast, the offset response monotonically increased with check size under scotopic and photopic conditions, which suggests a luminance component in the pattern electroretinogram. Consequently, the pattern electroretinogram to reversing checkerboards has to be regarded as a mixture of both pattern- (contrast) and luminance-specific components.

Analysis of infectious complications occurring after solid-organ transplantation

To improve our understanding of posttransplant infections, we analyzed bacterial, viral, fungal, parasitic, and other infections in 604 consecutive recipients of kidney (n = 518), kidney-pancreas (n = 82), kidney-liver (n = 3), or kidney-islet (n = 1) allografts (355 cadaveric, 14 living-unrelated, 235 living-related donors) who also received cyclosporine, azathioprine, and prednisone immunosuppression. Recipients of cadaveric grafts received additional induction immunosuppression (antilymphocyte globulin or murine monoclonal antibody OKT3). Rejection episodes were treated with high-dose steroids, and either antilymphocyte globulin or OKT3 was administered when clinically indicated. Perioperative antibiotics and posttransplant prophylactic acyclovir sodium or ganciclovir sodium, trimethoprim-sulfamethoxazole, and clotrimazole or nystatin (Mycostatin) were administered to all recipients. Two hundred thirteen patients (35.3%) were found to have had no identifiable infections, while 391 (64.7%) had either isolated bacterial (97 [16.1%]), viral (53 [8.8%]), or fungal (34 [5.6%]) infections or combination (concurrent or sequential) infections with bacterial plus viral (46 [7.6%]), bacterial plus fungal (66 [10.9%]), viral plus fungal (20 [3.3%]), bacterial plus viral plus fungal (64 [10.6%]), or bacterial plus viral plus fungal plus parasitic (11 [1.8%]) pathogens in the posttransplantation period. Renal allograft survival (percentage, actuarial method) was diminished in patients with infections at both 1 year (91% vs 83%) and 3 years (81% vs 76%) after transplantation, as was actuarial patient survival (1 year, 97% vs 92%; 3 years, 93% vs 88%). We conclude that infection remains a major cause of both patient demise and allograft loss following successful solid-organ transplantation.