A single-institution, retrospective examination of new contrast enhancement, progression, and pseudoprogression in IDH mutant glioma

2043

Background: IDH mutant glioma patients are followed by MRI, where new contrast enhancement (CEnew) is a hallmark of tumor progression. Interpretation of CEnew is confounded by pseudoprogression (PsP), the appearance of CEnew that spontaneously resolves on subsequent scans. PsP has been characterized in IDH wildtype patients, but is poorly understood in the IDH mutant category. This study represents an examination of the characteristics and impacts on patient survival of CEnew in IDH mutant gliomas. Methods: Of the 724 confirmed IDH mutant glioma patients treated at UCLA between 1998 and 2022, 587 were included (median follow-up = 5.23 years). Patients were excluded based on these criteria: <4 MRI scans, unknown IDH status, and unknown WHO 2016 diagnosis. CEnew was first identified by direct review of images and confirmed by the radiology report. Any new enhancement appearing on the first post surgical MRI was not considered CEnew. CEnew was interpreted as progression after surgical resection indicating tumor or the re-initiation of chemotherapy or radiation and was considered PsP after the resolution of enhancement without new treatment initiation. Some PsP patients could have received bevacizumab. Kaplan-Meier survival analyses were used to examine overall survival differences between groups. Results: 327 of 587 patients developed CEnew. The incidence of CEnew was higher in Grade 4 Astrocytoma (G4 Astro) versus all other pathologies and lowest in LO (p < 0.05). The Enhancement Free Survival (EFS) was shortest for G4 Astro patients (p =.002); LO patients had the longest median EFS of 2602 days (p = 0.002). The development of CEnew and presence of preoperative enhancement were both found to be negative survival prognosticators in all pathologies (p < 0.05). From our analysis, 92 patients developed PsP and 177 developed progression. The median duration of a PsP spot was 244 days. PsP spots appeared earlier than progression spots (median 538 vs 1113 days, p =.001). The incidence of PsP was highest in the G4 Astro group and lowest in LO patients. Survival analysis of patients with progression versus those with PsP and progression shows PsP is associated with longer OS in the entire cohort and the LO, AO, AA, and G4 Astro groups (p < 0.05). 100% of PsP patients received radiation therapy (RT). The median time from the end of RT to PsP was 209 days. Conclusions: While CEnew in IDH mutant gliomas is associated with reduced OS, poorer outcome is driven by progressors. PsP represents 28% of CEnew instances, typically occurs within 1 year of RT and have superior outcome to progressors and equivalent to of patients that do not display CEnew. [Table: see text]

Characterizing malignant transformation in patients with IDH-mutant glioma

2065

Background: Gliomas, which constitute the majority of primary brain cancers in adults, are assigned to a particular grade based on histological and molecular criteria set forth by the World Health Organization (WHO). A subset of initially low grade glioma patients transition to a higher grade at recurrence through a process known as malignant transformation (MT). Despite its significant implications on clinical prognosis, MT remains a poorly understood phenomenon in regards to its incidence rates, effects on survival, and potential prognostic factors. Our study aims to elucidate MT in patients that possess a mutation in the isocitrate dehydrogenase ( IDH) gene, one of the most common genetic alterations in gliomas. Methods: All known IDH mutant glioma patients, seen at UCLA between 1986 and 2022, who received at least 1 repeat resection for presumed recurrent disease were included. Based on surgical pathology reports, patients were categorized into MT and non-transforming progression groups, and further stratified by diagnosis in compliance with the 2016 WHO Classification of Tumors of the Central Nervous System. Relevant clinical information, including patient demographics, survival data, tumor microscopic descriptions, and magnetic resonance imaging, was accessed via electronic medical records. Kaplan Meier analyses were conducted to evaluate the predictive power of various clinical, pathological, and radiological markers. Results: Of 724 total IDH mutant patients screened, 253 received a second surgery and were thus incorporated in this study. Among the 196 patients with lower grade pathologies capable of MT, 129 (65.8%) progressed to a higher grade at recurrence while 71 (36.2%) did not. By diagnosis, the incidence rates of MT for initial grade 2 astrocytomas, grade 3 astrocytomas, and grade 2 oligodendrogliomas were determined to be 74.7%, 48.9%, and 66.1%, respectively. MT was associated with worse overall survival and post-recurrence survival compared to non-transformation in astrocytomas, a trend not seen in oligodendrogliomas. Across all relevant diagnoses, a subset of 36 MT patients did not receive treatment in the interval between initial and recurrent surgery, demonstrating the existence of spontaneously occurring MT. Furthermore, consolidating data from pathology and MRI reports revealed that a greater extent of abnormal molecular characteristics at initial diagnosis and earlier post-operative contrast enhancement may predict MT. Conclusions: These results highlight the distinct nature of gliomas that undergo MT, particularly in tumors of astrocytic differentiation. Considering its adverse impact on clinical outcome, understanding and anticipating this phenomenon is instrumental for the determination of optimal treatment among glioma patients.

The Tingathe Surge: a multi-strategy approach to accelerate HIV case finding in Malawi

Setting

Nineteen health facilities in rural, southeastern Malawi.

Objective

To describe the implementation and results of a 6-week intervention to accelerate human immunodeficiency virus (HIV) case finding.

Design

Six HIV testing strategies were simultaneously implemented. Routinely collected data from Ministry of Health registers were used to determine the number of HIV tests performed and of new cases identified. The weekly averages of the total number of tests and new cases before and during the intervention were compared. Testing by age group and sex was described. The percentage yield of new cases was compared by testing strategy.

Results

Of 29 703 HIV tests conducted, 1106 (3.7%) were positive. Of the total number of persons tested, 69.5% were women and 75.5% were aged >15 years. The yield of positive test results was 3.5% among women, 4.3% among men, 4.4% among those aged >15 years and 1.5% among those aged ⩽15 years. The average weekly number of tests increased 106.7% from 3337 to 6896 (P = 0.002). The average weekly number of positive cases identified increased 51.9% from 158 to 240 (P = 0.017). The testing strategy with the highest yield resulted in a 6.0% yield; the lowest was 1.3%. The yield for all strategies, except one, was highest in adult men.

Conclusion

A multi-strategy approach to HIV testing and counseling can be an effective means of accelerating HIV case finding.

[Importance of the Watzke-Allen test in diagnostics and staging of macular holes]

BACKGROUND

The Watzke-Allen test (WAT) is a simple diagnostic tool designed for the diagnosis of full thickness macular holes (FTMH) but due to the rapid progress of imaging diagnostics it was replaced by spectral domain optical coherence tomography (SD-OCT) of macular pathologies. The aim of this study was to examine if the WAT is able to distinguish between the different FTMH stages.

METHODS

In 57 eyes of 57 patients with clinical evidance of FTMH, the WAT was first performed followed by SD-OCT examination and a distinction was made between a negative (slit beam normal) and a positive sign (slit beam modified as groove and hourglass configuration or completely broken).

RESULTS

In 49 out of 57 patients the WAT was positive (hourglass 46 patients and broken 3 patients). Based on the SD-OCT results the following diagnoses were made: lamellar macular holes (LMH, 3 patients), vitreomacular traction (VMT, 4 patients), small macular hole (≤ 250 µm,  5 patients), medium sized macular hole (250-400 µm, 11 patients) and large macular hole (≥ 400 µm,  34 patients). In 91 % of the patients with medium and large FTMH, the WAT was positive, whereas the WAT was positive in only 67 % of patients with small FTMH, VMT and LMH. The sensitivity for large and medium FTMH was 93 % but the specificity was only 33 %.

CONCLUSION

The WAT was positive in a high percentage of patients with large and medium sized macular holes as well as patients with small macular holes and LMH. The sensitivity of certain indications for treatment was 93 % but the specificity was only 33 %; therefore, the WAT alone is not suitable for a certain preoperative differentiation of macular alterations.

[Serum adenosine deaminase as a parameter for activity in sarcoidosis]

Adenosin deaminase (ADA) is an enzyme of purine metabolism and reflects the involvement of the cellular immune system. The ADA serum levels were tested in 130 healthy blood donors, and in 98 patients (pts) with sarcoidosis; 59 pts with active and 39 pts with inactive sarcoidosis. These two patient groups were separated into treated and untreated; the active group was divided into an acute onset group (12 pts) and a group with chronic disease (47 pts). The disease activity was determined on the basis of clinical symptoms, chest x-ray and lung function tests. ADA was compared to angiotensin converting enzyme(ACE), neopterin (NPT), and soluble interleukin-2 receptor (sIL-2 R). ADA activity was measured colorimetrically according to a method of Giusti with slight modifications. ACE was determined by a commercial kit by Fujerbio, Japan. NPT and sIL-2 R were evaluated by commercial enzyme-linked immunosorbent assays. The ADA activity in controls was 18.8 +/- 3.8 U/I (mean +/- SD), the upper normal serum range (mean +/- 2SD) was established at 26.4 U/I. Serum ADA levels in the group with active sarcoidosis (33.5 +/- 14.3 U/I, p < 0.0001) were significantly higher than those in healthy controls and in inactive disease (19.6 +/- 5.8 U/I, p < 0.0001). Sensitivity and specificity were: ADA 75%/92%, ACE 49%/85%, NPT 78%/74%, sIL-2 R 81%/57%.

CONCLUSION

Our findings demonstrate that the course of the disease can be monitored by measurement of the serum ADA. In comparison to the other parameters, measurement of the serum ADA indicates a greater discrimination between active and inactive disease.

[The value of colloid scintigraphy and erythrocyte scintigraphy in detecting acute or intermittent gastrointestinal hemorrhages]

PURPOSE

In a retrospective analysis the diagnostic value of two scintigraphic methods was compared with each other.

METHOD

104 patients with acute or intermittent gastrointestinal haemorrhage were examined with 121 scintigraphic studies. We compared scintigraphic results with surgical findings, endoscopic results or final clinical diagnosis. We used two scintigraphic methods, colloid scintigraphy and in vivo/vitro red blood cell scintigraphy.

RESULTS

Our scintigraphic findings reached a sensitivity of 72% and a specificity of 100%. We calculated a sensitivity of 68% for colloid scintigraphy and a sensitivity of 79% for red blood cell scintigraphy. The correct localisation of bleeding was successful in 52 (98%) cases.

CONCLUSIONS

Our results demonstrate that red blood cell scintigraphy is the method of choice in detecting intermittent gastrointestinal hemorrhage. We believe that with new preparation kits for in vivo labelling red blood cell scintigraphy will become seriously competitive for the colloid scintigraphic method.

[Role of serum adenosine deaminase as an immune parameter of tuberculosis]

We measured serum levels of adenosine-deaminase (ADA) in 44 tuberculosis patients, 70 patients with lung cancer pre treatment, and 130 normal blood donors. Increased ADA levels were found in 64.4% of the tuberculosis patients, in 95.2% in the case of bacillary tuberculosis, but only in 2.8% in the tumor patients. ADA serum levels were statistically significantly increased in tuberculosis patients when compared to lung cancer patients and controls and did not differ between controls and the tumor group. We conclude that serum ADA is a selective marker of immune stimulation in tuberculosis but not in lung cancer. Serum levels positively correlated to the disease extent in tuberculosis of immunocompetent patients. This marker deserves further investigation with respect to its clinical significance.

Chlorate poisoning: mechanism of toxicity

Intoxications with chlorate salts are characterized by methaemoglobin formation, haemolysis and renal insufficiency. The toxic effects on the erythrocyte can be reproduced in vitro. Incubation of human and rabbit erythrocytes with chlorates induces a concentration-dependent oxidation of haemoglobin. This methaemoglobin formation is followed by denaturation of the globin, a cross-linking of erythrocyte membrane proteins and an inactivation of membrane enzymes. The high sensitivity of glucose-6-phosphate dehydrogenase to denaturation by chlorate explains the inefficacy of methylene blue to reduce methaemoglobin formed, as the antidotal effect of methylene blue depends on NADPH formed mainly by the oxidation of glucose-6-phosphate. The observed changes occur only in the presence of methaemoglobin which forms a destabilising complex with chlorate. Methaemoglobin thus autocatalytically increases methaemoglobin formation and destruction of the erythrocyte. As the rabbit is known to have a high methaemoglobin-reduction capacity, human and rabbit erythrocytes were compared. In vitro, the rabbit erythrocyte is less sensitive to oxidative attack than the human red cell. In vivo, an oral dose of sodium chlorate (1 g/kg body wt.) resulted in high serum (16 +/- 4 mM) and urine concentrations (246 +/- 99 mM) in the rabbit. Methaemoglobin was not formed nor could a nephrotoxic effect be observed. These experiments also indicate that the nephrotoxicity of chlorate is mediated by methaemoglobin catalysis.

[Computerized tomography-guided fine needle biopsy. Current perspectives in biopsy diagnosis]

253 cutting needle biopsies from 240 patients (151 men, 89 women; mean age 68 [23-84] years) were reviewed. The biopsies were taken under computed (CT) tomography guidance from various parts of the body (pancreas: n = 48, liver: n = 32, other upper abdominal organs: n = 5, mediastinum: n = 27, lung: n = 37, kidney: n = 13, adrenals: n = 8, retroperitoneum: n = 35, pelvis: n = 37, pleura: n = 4, chest wall: n = 6). The data were evaluated retrospectively. In 86% of cases meaningful clinical information was obtained in the form of a definite diagnosis (74%) or of a presumptive or differential diagnosis (12%). As a rule it was possible to assess the degree of malignancy and to ascertain the exact nature of the condition; the latter was true not only of malignant but also of benign lesions. In the majority of cases this had important implications. In just under 14% of all cases the target area was missed and no diagnosis could be made. To raise the chances of obtaining a representative biopsy multiple punctures were performed in 44% of the CT-guided biopsies. In 61 cases (24%) the diagnosis was checked against further tissue samples and in four cases the diagnosis based on needle biopsy material had to be revised. In all, only two complications were recorded; both were mild and did not require treatment. In terms of diagnostic value, CT-guided fine needle biopsies proved considerably superior to conventional cytological studies of fine needle aspiration material.

[Detection of a pheochromocytoma in the urinary bladder wall]

We present the case of a 23-year old female patient with clinical signs and biochemical results of a pheochromocytoma. Abdominal ultrasound gave no hints on localisation. Angiography demonstrated a richly vasculated tumour in the region of the superior urinary bladder. Computed tomography (CT) was able to localise the tumour but could not differentiate the tumour origin in bladder or uterus. The selective venous catheter blood sampling confirmed the localisation of the norepinephrine producing pheochromocytoma in the inferior pelvic region. Intraoperative diagnosis turned out to be an extra-adrenal pheochromocytoma of unknown tumour status in the dorsal bladder wall.

[HM-PAO cerebral blood flow scintigraphy in the manifestation stage of brain death]

We monitored 27 patients with HM-PAO-perfusion scintigraphy during the progress of cerebral death. The results of scintigraphy correlate well with cerebral angiography. Advantages are the possibility of bedside-examination, the non-invasiveness of the method and the possibility of in-vivo control. The non-visualized-brain in dynamic scintigraphy is a valuable additional method in the determination and documentation of cerebral death.

[The radiologic picture of bronchopulmonary aspergillosis]

The increasing incidence of conditions associated with immune suppression, either as part of the illness or as the result of treatment, makes it necessary to investigate the possibility of fungus infections whenever there are broncho-pulmonary changes. In this respect, aspergillus is a common infection which produces more or less typical radiological changes. It often requires a variety of radiological procedures, including the use of CT and nuclear medicine. The latter can be useful in the allergic form of aspergillosis used for ventilation scintigraphy. The possibility of aspergillosis must be brought to the attention of the clinicians by the radiologist, even in cases that are not entirely typical.

Specific chromosomal abnormalities characterize fibrosarcomas of bovine papillomavirus type 1 transgenic mice

In the BPV1.69 line of transgenic mice, the bovine papillomavirus type 1 genome elicits both benign dermal fibroblastic proliferation (fibromatoses) and malignant fibrosarcomas. Because these lesions arise only with time, nonviral factors appear to be involved. We have karyotyped several primary tumors as well as a series of low-passage cell lines derived both from fibromatoses and from fibrosarcomas. The fibrosarcomas, but not the preneoplastic fibromatoses, show consistent abnormalities of one or both of two chromosomes, chromosome 8 (trisomy or duplication) and chromosome 14 (monosomy or translocation). The chromosomal abnormalities are not a direct consequence of the viral integration, which we have mapped to chromosome 15 by in situ hybridization. These results suggest that transgenic mice can be used to study the role(s) of cytogenetic changes in tumorigenesis and may direct the search for genes involved in tumor progression.

[Current developments in the radiologic diagnosis of the adrenal glands]

Cross-sectional imaging techniques have dramatically improved the diagnosis of adrenal disease. In most patients with endocrine-active adrenal disease, CT is the only imaging test needed to establish the correct diagnosis. Adrenal venography with blood sampling may provide important additional information in patients with Conn adenoma. Magnetic resonance imaging and (IMBG) scintigraphy appear to be the best imaging tests for the localization of multiple or extra-adrenal pheochromocytomas. Inactive adrenal tumors detected incidentally are a problem as for as diagnosis is concerned, since inactive adrenal adenomas have to be differentiated from carcinomas and metastases. MRI is rarely helpful in these cases. For patients with a known primary tumor, the authors recommend CT-guided biopsy. In all other cases a follow-up study often reveals that the adrenal tumor detected is benign.

High-affinity SV40 T-antigen binding sites in the human genome

We describe two different approaches to isolate human genomic sequences possessing high-affinity binding sites for the simian virus 40 (SV40) large T antigen. First, SV40 T antigen was added to Sau3A-restricted human DNA; the resulting T-antigen-DNA complexes were collected after repeated passages through nitrocellulose filters. The second approach involves the specific immunoprecipitation of chromatin fragments, generated by Sau3A treatment of nuclear chromatin from SV40-transformed human cells. The DNA fragments obtained were cloned in plasmid vectors for further investigation. Using the filter binding approach we isolated four different fragments with high-affinity binding sites. The binding site in one fragment was related to the strong T-antigen binding site I in the SV40 genome. The other three fragments contained multiple recognition pentamers, GA(G)GGC. Only one fragment with a high-affinity binding site was identified among the immunoprecipitable chromatin fragments. This DNA fragment belongs to the L1 family of human repetitive DNA. We present evidence suggesting that a significant fraction of human L1 elements possesses T-antigen binding sites. L1-related sequences appear as extrachromosomal elements in an SV40-transformed human cell line, and the amount of extrachromosomal L1 DNA was found to increase after fusion of transformed cells to permissive monkey cells.

[Nuclear medical differentiation of focal lesions of the liver]

Radio-colloid scintigraphy, hepatobiliary scintigraphy and blood pool scanning with tagged red blood cells are well-established methods of nuclear medicine for the differential diagnosis of hepatic lesions. Hepatic hemangiomas and focal nodular hyperplasia can be differentiated in over 90% of cases. The sensitivity of single-photon emission computer tomography (SPECT) in the detection of liver masses greater than 2 cm diameter is 92%-98%.

Effects of long-term treatment with 120 mg of sustained-release isosorbide dinitrate and 60 mg of sustained-release nifedipine on myocardial perfusion

Forty patients with coronary artery disease and scintigraphically proven myocardial ischemia were randomized into 2 groups receiving 4 weeks of treatment with either 120 mg of isosorbide dinitrate (ISDN) release or 60 mg of nifedipine release. Control exercise testing and myocardial scintigraphy were continued until anginal pains occurred, and repeated at identical individual workloads at the end of the 4 weeks of drug therapy. Myocardial scintigrams were evaluated by quantitative recording of counts in 60 segments/frame. Twenty patients in the ISDN group (group I) exhibited 47 significantly ischemic areas. The remaining 20 patients (group II), treated with nifedipine, had 50 ischemic areas before therapy. In the ischemic areas in group I, there was a mean difference of 30.9% between counts at rest and during exercise in the pretreatment period, and a difference of 18.1% after therapy (39.0%). In group II, the pretreatment difference was 28.8%, decreasing to 20.6% after therapy (17.8%). Both groups of patients were subsequently subdivided into 3 subsets: (1) significantly improved perfusion, (2) significant worsening, and (3) unchanged myocardial perfusion. Group I had 59.5% of areas with significant improvement and 10.6% of areas with significant worsening. In 29.7% of the areas, the findings were unchanged. Group II had improvement in 40% of areas, of significantly worsened areas in 6%, and unchanged areas in 54%, in both groups myocardial ischemia was reduced by therapy, but ISDN improved myocardial perfusion to a considerably greater extent than did nifedipine.

[Imaging procedures and follow-up in pediatric surgical diseases]

The most important modern imaging diagnostics are the ultrasound, scintigraphy, computed tomography and recently the nuclear magnetic resonance (NMR). The diagnostic tools should be used one after another, always starting with the easiest to perform, with low risk and no harm to the patient, at low costs. In routine diagnostic procedures (e.g. blunt abdominal trauma) this will be the sonography. The result of the ultrasound may give rise to other, but more invasive methods. Computed tomography, e.g. may give more detailed information about position, size and operability of a tumor whereas scintigraphy has its strong point in disclosing functional organ disorders (e.g. kidney, liver and especially in splenic transplants).

[Value of phlebo-scintigraphy for clarifying thromboembolic processes in the pelvis and legs]

In 64 patients suspected of having had pulmonary emboli due to thrombo-embolic disease, radionuclide venography (RNV) and contrast phlebography were carried out (84 examinations of extremities, 64 examinations of extremities and pelvis). Phleboscintigraphy proved informative in the thigh and in the pelvis. Around the knee, RNV was sufficiently accurate as a screening method. In the calf, RNV was of diagnostic value only in the presence of positive findings on scintigraphy.

[Demonstration and localization of hemorrhage in the intestinal tract. Comparison between 99mTc-colloid scintigraphy and selective angiography of the visceral vessels]

In 17 patients with suspected bleeding in the lower intestinal tract 23 scintigraphic studies were performed with Tc-colloid, followed in each case by visceral-artery angiography. Comparison of the two methods with the final clinical diagnosis indicated that angiography was correct in 6 of 23 examinations (26%), scintigraphy in 12 of 23 (52%). All scintigraphically negative results were negative also angiographically. Noninvasive, relatively unstressful scintigraphy should be performed for immediate diagnosis in any case of acute bleeding. Emergency-type angiography is reasonably performed only if scintigraphy is positive.

[Results of transvenous digital subtraction angiography with a 57 cm image intensifier in circulatory disorders of the lower extremities]

The size of conventional image intensifiers is a limiting factor in performing transvenous digital subtraction angiography of the lower extremities. The results of transvenous digital subtraction angiography using a 57 cm image intensifier on 205 patients with vasoocclusive disease of the legs are presented. Two exposed fields sufficed in most cases for demonstration of all arteries, from the aortic bifurcation to the trifurcation at the lower leg. The principal advantages were the reduction of the contrast medium volume and the decrease in examination time. The reduced resolving power was a limiting factor in evaluating discrete wall lesions and of small vessels, but this did not induce diagnostic difficulties. The studies were evaluated retrospectively by an experienced vascular surgeon and in 85% of the cases were considered to be of diagnostic value.

[Potentialities of radiological diagnosis of injuries to the dorsal pelvic ring]

Thirty-five patients with fractures of the anterior pelvis, in whom there was clinical suspicion of trauma to the posterior part of the pelvis, were examined by conventional radiology, bone scintigraphy and computed tomography, and the results were compared. CT provided the most information and made it possible to evaluate the soft tissues and organs of the pelvis. Bone scintigraphy produced the same number of abnormal findings as CT (sensitivity 100%), but was unable to differentiate between lesions of the sacro-iliac joints, fractures of the sacrum, combined injuries or degenerative processes. A positive bone scintigram is a reliable finding, with a high predictive value. A negative result excludes a fracture or other lesions of the dorsal portion of the pelvis completely. Conventional radiographs provided a correct diagnosis in only 37.1% as compared with CT.

[1 year's experience with a 57-cm image intensifier in a universal roentgen work station]

3342 patients were examined by means of a 57 cm image intensifier during one year. The installation permits examination with the patient standing or lying. The resolution was measured with a lead grid under conditions resembling actual practice and were found to be similar to those obtained with angiographic equipment. Using a medium format technique for examining the gut and vascular system resulted in radiographic quality which was not significantly different from the use of a large format technique. For examination of the skeleton, radiographic quality, using the intensifier, was markedly poorer than that resulting from Bucky examinations. There was no diagnostic difference when carrying out lymphograms. The large intensifier window of 53 cm was particularly advantageous for DSA of the pelvic and lower limb vessels when compared with smaller intensifiers. Possible savings of film and contrast medium costs are discussed.

High-performance liquid chromatography with column switching for the analysis of biogenic amine metabolites and pterins

An automatic high-performance liquid chromatographic system with facilities for column switching is described which involves minimal pre-treatment of biological samples, separates complex mixtures of compounds in a short period of time and uses fluorimetric or amperometric detection. The system has been applied to the analysis of oxidized pterins in urine and reduced pterins in cerebrospinal fluid and rat brain fractions (R- and S-enantiomers of tetrahydrobiopterin resolved). The system can also be used for the analysis of most of the dopamine and serotonin metabolites in cerebrospinal fluid and brain fractions from norepinephrine to serotonin.

Erythrocyte membrane alterations as the basis of chlorate toxicity

The effects of sodium chlorate and of sodium nitrite on human erythrocytes were studied in vitro. Nitrite rapidly oxidised haemoglobin and glutathione; reduction of methaemoglobin (Hbi) by methylene blue was complete during 3 h of incubation with nitrite. With chlorate, a concentration-dependent lag phase was seen before Hbi was formed. After prolonged incubation, Hbi could no longer be reduced with methylene blue. Several other effects were observed that explain the clinical picture of chlorate poisoning which involves haemolysis followed by disseminated intravascular coagulation and renal failure: increased permeability to cations, increased resistance to hypotonic haemolysis and prolonged filtration time through polycarbonate membranes with cylindrical pores of 5 micron diameter. This suggests an increased membrane rigidity due to membrane protein polymerisation, as demonstrated by SDS polyacrylamide gel electrophoresis. Simultaneously, erythrocyte enzymes were inactivated, primarily glucose-6-phosphate dehydrogenase which is necessary for the therapeutic effect of methylene blue. This explains the inefficacy of methylene blue in the treatment of a case of chlorate poisoning that we observed (Arch. Toxicol., 48 (1981) 281).

Effect of vanadate on myocardial force of contraction

Ammonium vanadate (NH4VO3; 50-1000 microM) increases the force of contraction of isolated electrically driven cat papillary muscles in a concentration-dependent manner. The positive inotropic effect (PIE) of NH4VO3 became significant at 50 microM and was maximal at 500 to 1000 microM. It was accompanied by an increase in the rate of force development, in the rate of relaxation and in relaxation time of the isometric contraction. Similar results as with NH4VO3 were also observed in the presence of 1 microM propranolol, 5 microM phentolamine or after reserpine-pretreatment (5 mg/kg i.p.). These results indicate that vanadate produces a direct PIT in ventricular cardiac muscle which is unlikely to be mediated by alpha- or beta-adrenoceptor stimulation. In cat left atrial strips, however, vanadate ions produced a negative inotropic effect through a hitherto unknown mechanism. Vanadate effects similar to those observed in the cat heart were obtained in ventricular and atrial preparations from bovine hearts.

[Comparative investigations (computed tomography, X-ray diagnostics, scintigraphy) for the detection of radiation-induced alterations of the lung (author's transl)]

Radiation-induced alterations of the parenchyma of the lung were investigated in 24 rabbits before, during and after irradiation of the left lung. Of the experimental animals 12 received a surface dose of 50 Gy, the other half 40 Gy, equivalent to a focal dose of 47.5 resp. 38 Gy in the middle of the lung, with a fractionation of 10 Gy per week. By means of lung-scintigraphy (99mTc-MAA) radiation-induced obstructions to perfusion could be demonstrated in 93% of the experimental animals, only in 37% the detection of radiopneumonia was possible by computed tomography or by a roentgenogram of the thorax. In 70% of the experimental animals scintigraphic alterations could be detected already during radiotherapy, the alterations visible by computed tomography or roentgenology appeared much later. Here computed tomography allowed an earlier identification of differences in absorption than X-ray diagnostics.

["Cold lesions" in bone scintigraphy (author's transl)]

Frequency and location of "cold lesions" has been analysed in 1000 consecutive bone scans. Among the 554 abnormal cases there were 18 (1,8% of the total) with localized diminished activity due to metastatic lesions and 5 (0,5%) secondary to radiation osteitis. 10 of the 18 patients with metastatic disease had pure defects while 8 showed a reactive margin. It is pointed out that the quality of the examination is crucial for the demonstration of such defects and that single scans of the different regions of the skeleton are superior to a whole body scan. The survey of the literature shows that "cold lesions" are predominant in malignant bone diseases, however no relation exists to a definite histology.

[Absorption and excretion of g-strophanthin after intravenous or sublingual administration (author's transl)]

Tritiated g-strophanthin was administered to six volunteer patients in a dose of 0.25 mg intravenously and 6.0 mg sublingually 1-3 weeks apart. Radioactivity in plasma and urine was measured afterwards for 48 or 96 hours, respectively. Plasma concentration fell to about a fifth of the maximal concentration within 6 min after intravenous administration, total excretion within three days being about 50%, with a half-time of 11 hours. Measurable plasma concentration after sublingual administration was demonstrable only after 15 min in some and after 2 hours in all the six patients. Radioactivity counts increased up to the 24th hour, in three patients up to the 48th hour. Maximal plasma concentration ranged from 4.7 to 0.7 ng/ml, corresponding to levels reached 15 min or 4 hours, respectively, after intravenous administration. Urinary radioactivity reached its maximum after 24-48 hours and then decreased. Within three days 0.6 and 2.5% of the administered radioactivity was recovered, corresponding to the g-strophanthin doses of 0.072 to 0.3 mg. The findings once again confirm the low and irregular absorption of g-strophanthin when administered sublingually or orally.

New tyrosine metabolites in humans: hawkinsin and cis- and trans-4-hydroxycyclohexylacetic acids. Unusual adsorption of deuterated and non-deuterated hawkinsin during gas chromatography

In a new inborn error of metabolism, where obviously a defect of 4-hydroxyphenylpyruvate dioxygenase (EC 1.13.11.27) exists, hawkinsin [(2-cystein-S-yl-1,4-dihydroxycyclohex-5-en-1-yl) acetic acid] and cis- and trans-hydroxycyclohexylacetic acids were found in the urine. A partially reversible adsorption of deuterated and non-deuterated hawkinsin (as the penta-trimethylsilyl derivative) in gas chromatography--mass spectrometry has inhibited a mass fragmentographic quantitation of this compound to date. However, quantitation seems to be possible using mass framentography of 1,4-dihydroxycyclohexylacetic acid, formed by desulfuration of the sample with active nickel.