Pax9-deficient mice lack pharyngeal pouch derivatives and teeth and exhibit craniofacial and limb abnormalities

Pax genes have been shown to play important roles in mammalian development and organogenesis. Pax9, a member of this transcription factor family, is expressed in somites, pharyngeal pouches, mesenchyme involved in craniofacial, tooth, and limb development, as well as other sites during mouse embryogenesis. To analyze its function in vivo, we generated Pax9 deficient mice and show that Pax9 is essential for the development of a variety of organs and skeletal elements. Homozygous Pax9-mutant mice die shortly after birth, most likely as a consequence of a cleft secondary palate. They lack a thymus, parathyroid glands, and ultimobranchial bodies, organs which are derived from the pharyngeal pouches. In all limbs, a supernumerary preaxial digit is formed, but the flexor of the hindlimb toes is missing. Furthermore, craniofacial and visceral skeletogenesis is disturbed, and all teeth are absent. In Pax9-deficient embryos tooth development is arrested at the bud stage. At this stage, Pax9 is required for the mesenchymal expression of Bmp4, Msx1, and Lef1, suggesting a role for Pax9 in the establishment of the inductive capacity of the tooth mesenchyme. In summary, our analysis shows that Pax9 is a key regulator during the development of a wide range of organ primordia.

Selective disactivation of neurofibromin GAP activity in neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a common familial tumour syndrome with multiple clinical features such as neurofibromas, café-au-lait spots (CLS), iris Lisch nodules, axillary freckling, optic glioma, specific bone lesions and an increased risk of malignant tumours. It is caused by a wide spectrum of mutations affecting the NF1 gene. Most mutations result in the loss of one allele at the DNA, mRNA or protein level and thus in the loss of any function of the gene product neurofibromin. The idea of the simultaneous loss of several different neurofibromin functions has been postulated to explain the pleiotropic effects of its loss. However, we have identified a novel missense mutation in a family with a classical multi-symptomatic NF1 phenotype, including a malignant schwannoma, that specifically abolishes the Ras-GTPase-activating function of neurofibromin. In this family, Arg1276 had mutated into proline. Based on complex biochemical studies as well as the analysis of the crystal structure of the GTPase-activating protein (GAP) domain of p120GAP in the presence of Ras, we unequivocally identified this amino acid as the arginine finger of the neurofibromin GAP-related domain (GRD)-the most essential catalytic element for RasGAP activity. Here, we present data demonstrating that the mutation R1276P, unlike previously reported missense mutations of the GRD region, does not impair the secondary and tertiary protein structure. It neither reduces the level of cellular neurofibromin nor influences its binding to Ras substantially, but it does completely disable GAP activity. Our findings provide direct evidence that failure of neurofibromin GAP activity is the critical element of NF1 pathogenesis. Thus, therapeutic approaches aimed at the reduction of Ras.GTP levels in neural crest-derived cells can be expected to relieve most of the NF1 symptoms.

Targeted disruption of Pax1 defines its null phenotype and proves haploinsufficiency

The murine paired box-containing gene Pax1 is required for normal development of the vertebral column, the sternum, and the scapula. Previous studies have shown that three natural Pax1 mouse mutants, the undulated alleles, exhibit phenotypes of different severity in these skeletal elements. Nevertheless, these analyses have not clarified whether the semidominant Undulated short-tail (Uns) mutation, in which the complete Pax1 locus is deleted, represents a null allele. Moreover, the analyses of the classical undulated mutants did not allow a conclusion with respect to haploinsufficiency of Pax1. To address both questions we have created a Pax1 null allele in mice by gene targeting. Surprisingly, the phenotype of this defined mutation exhibits clear differences to that of Uns. This result strongly indicates the contribution of additional gene(s) to the Uns mutant phenotype. Furthermore, the phenotype of mice heterozygous for the null allele demonstrates that Pax1 is haploinsufficient in some though not all skeletal elements which express Pax1 during embryonic development.

Glutaric aciduria type 1: an underdiagnosed cause of encephalopathy and dystonia-dyskinesia syndrome in children

Two cases of glutaric aciduria type 1 (GA 1) are presented. GA 1 is probably underdiagnosed and misdiagnosed, and may explain a proportion of cases of extrapyramidal and 'postencephalitic' cerebral palsy. Most cases of GA 1 present with a severe dystonic-dyskinetic syndrome following an acute encephalopathy. Asymptomatic cases have also been described, complicating genetic counselling and prenatal diagnosis. We raise awareness of GA 1 and stress that if clinically suspected, immediate institution of therapy may reduce late morbidity. Moreover, if recognised in the presymptomatic stage, early institution of treatment may prevent the onset of neurological symptoms. GA 1 is an inborn error of lysine and tryptophan catabolism, caused by deficiency of the enzyme, glutaryl coenzyme-A dehydrogenase. Urine organic acid analyses may be negative. Blood acylcarnitine profile has recently been employed as a more sensitive test but was negative in both our patients. Enzyme assay remains the definitive diagnostic test.

Demonstration of the efficacy of ginkgo biloba special extract EGb 761 on intermittent claudication--a placebo-controlled, double-blind multicenter trial

BACKGROUND

A multicentric, randomized, placebo-controlled double-blind study on ginkgo biloba special extract EGb 761 (Tebonin forte) in patients suffering from peripheral occlusive arterial disease (POAD) in Fontaine stage II b was carried out in order to prove its clinical efficacy in this indication according to guidelines of European Community authorities and the German Angiological Society and to confirm the results of former clinical studies with EGb 761.

PATIENTS AND METHODS

In total, 111 patients with angiographically proven POAD in Fontaine stage II b and intermittent claudication (pain-free walking distance < 150 m on the treadmill) were recruited in 5 centers and treated with either EGb 761 or placebo at a daily dose of 3 times 1 film-coated tablet over a duration of 24 weeks following a 2-week placebo run-in period. The primary response variable was the difference of the pain-free walking distance between the start of treatment and after 8, 16 and 24 weeks as measured on the treadmill (walking speed 3 km/h and slope of 12%) under standardized conditions.

RESULTS

At the start of the treatment period, the mean pain-free walking distances were very similar with 108.5 m in the EGb 761 group and 105.2 m in the placebo group. At the end of the treatment period these values increased to 153.2 m and 126.6 m, respectively. The group differences were statistically significant at all three control visits with p = 0.017, p = 0.007, and p = 0.016. The differences for the maximum walking distance and the relative increases of the pain-free walking distance and the maximum distance were also significantly higher in the EGb 761 group with p-values < 0.05 each. In both groups Doppler indices remained nearly unchanged during therapy. The subjective assessment of the patients demonstrated an amelioration of complaints in both groups. Tolerability was very good with no adverse events under EGb 761 and one case of heartburn and gastric pain in the placebo group.

CONCLUSIONS

It can be concluded from the results of this study that treatment with EGb 761 in POAD patients with Fontaine stage II b is very safe and causes a significant and therapeutically relevant prolongation of the patients' walking distance.

[Invagination of the vermiform appendix in mucinous cystadenoma]

Intussusception of the appendix vermiformis in adults is an uncommon event. The combination of a mucinous cystadenoma with an intussuscepted appendix is extremely rare. Clinical symptoms are nonspecific; in most cases the correct diagnosis is not made before surgical exploration. With the radiologic and endoscopic presentation of a polypoid lesion of the caecum, a neoplasm is often considered. Endoscopic appendectomy or disinvagination by enema have been described. Thus the definitive therapy is surgery and depends on the histological diagnosis.

The effect of the anti-angiogenic agent TNP-470 on tumor growth and vascularity in low passaged xenografts of human gliomas in nude mice

The effect of the anti-angiogenic agent TNP-470 on tumor growth, vascular area, vascular density and tumor perfusion of two different subcutaneously implanted human glioma xenografts (E98 and E106) in nude mice was evaluated. Vascular parameters were investigated with an image analysis system. For both tumor lines a small but significant tumor growth suppression was observed. However, no differences in vascular parameters between TNP-470 treated tumors and controls could be found after 6 weeks of treatment. It is concluded that although TNP-470 is a promising anti-angiogenic agent in many tumor types, at least 2 glioma lines seem to be partly resistant to its anti-angiogenic effects. Further evaluation of the effects of combination of TNP-470 and cytostatic agents or radiotherapy in human glioma xenografts are required to determine the place of anti-angiogenic therapy in general and treatment with the anti-angiogenic agent TNP-470 more specifically in the treatment of human gliomas.

Two novel mutations in exons 19a and 20 and a BsaBI [correction of BsaI] polymorphism in a newly characterized intron of the neurofibromatosis type 1 gene

Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder. It is caused by mutations in the NF1 gene, which comprises 60 exons and is located on chromosome 17q11.2. A total of 170 unrelated NF1 patients were screened for mutations in four exons by temperature-gradient gel electrophoresis. Preparatory work revealed the presence of a previously uncharacterized intron (19a) in what was previously designated exon 19; this allowed us to develop assays for genomic mutation screening in the newly defined exons 19a and 19b. Two novel NF1 mutations were detected: a single-base insertion in exon 19a creating a frameshift, and a second mutation affecting the splice donor site of intron 20 and leading to skipping of exon 20. A novel BsaBI polymorphism was identified in intron 19a.

Impact of strain heterogeneity on Lyme disease serology in Europe: comparison of enzyme-linked immunosorbent assays using different species of Borrelia burgdorferi sensu lato

For the standardization of serological tests for Lyme borreliosis (LB) in Europe, the influence of the heterogeneity of Borrelia burgdorferi sensu lato must be assessed in detail. For this study four immunoglobulin M (IgM) and IgG enzyme-linked immunosorbent assays (ELISAs) with octyl-beta-D-glucopyranoside extracts of strains PKo (Borrelia afzelii), PBi (Borrelia garinii), and PKa2 and B31 (both B. burgdorferi sensu stricto) were compared. Strains PKo, PBi, and PKa2 at the passages used for antigen preparations abundantly expressed outer surface protein C (OspC), whereas strain B31 at the passage used for antigen preparation did not express OspC. Sera (all from Germany) from 222 patients with clinically defined LB of all stages, 133 blood donors, and 458 forest workers were tested. None of the forest workers had symptoms consistent with LB at the time that the samples were collected. For IgM tests, receiver operating characteristic curves demonstrated that discrimination between sera from patients and blood donors was best with strain PKo and worst with strain B31. The discriminatory abilities of the four IgG ELISAs were similar in a diagnostically reasonable specificity range (90 to 100%). More than 20% of the sera from forest workers reacted strongly in the PKo IgG ELISA (optical density value, >1.5; other assays, less than 8%). Western blots of the sera with the most discrepant ELISA results revealed almost exclusive reactivity with p17. This highly immunogenic antigen is only expressed by strain PKo. This observation might be important for the development of assays enabling discrimination between asymptomatic or previous infection and active disease.

[Nitric oxide, L-arginine and the kidney. Experimental studies of new therapy approaches]

BACKGROUND

Nitric oxide (NO) is a small gaseous molecule with multiple biological effects. NO is produced from the semi-essential amino acid L-arginine by NO synthases (NOS). In the kidney, neuronal NOS (bNOS), which is localized in the macula densa, and endothelial NOS (ecNOS) are involved in the regulation of glomerular hemodynamics. Dysfunction of these enzymes may cause glomerular hypertension and increased intraglomerular platelet aggregation. NO production in high tissue concentrations can be achieved by activation of an inducible NOS isoform (iNOS) and may act as a potent mediator of inflammation in immune-mediated renal diseases. Selective inhibition of iNOS may, therefore, become a novel anti-inflammatory approach in the treatment of glomerulonephritis. Based on experimental data, the potential importance of NO and other metabolites of L-arginine in the pathophysiology and therapy of renal diseases is summarized in this article.

CONCLUSION

Modulation of the renal L-arginine/NO-system represents a promising therapeutic target in the treatment of acute an chronic kidney diseases.

Pax genes and organogenesis: Pax9 meets tooth development

Pax genes encode a family of transcription factors that play key roles during embryogenesis. They are required for the development of a variety of organs including the nervous and muscular system, skeleton, eye, ear, kidney, thymus, and pancreas. Whereas the developmental roles of many of the nine known Pax genes have been analyzed in great detail, a functional analysis of Pax9 has just begun. During mouse embryogenesis, Pax9 exhibits a highly specific expression pattern in derivatives of the foregut endoderm, somites, limb mesenchyme, midbrain, and the cephalic neural crest. In the mandibular arch mesenchyme, the expression of Pax9 marks the prospective sites of tooth development prior to any morphological signs of odontogenesis and is maintained in the developing tooth mesenchyme thereafter. To understand the function of Pax9 during mouse embryogenesis, we recently have created a null allele by gene targeting. Preliminary analyses show that Pax9 is essential for the formation of teeth, and we conclude that Pax9 is required for tooth development to proceed beyond the bud stage. Here, we briefly summarize our current knowledge about Pax genes and introduce Pax9 to the growing family of factors which are involved in tooth development.

Antagonistic interactions between FGF and BMP signaling pathways: a mechanism for positioning the sites of tooth formation

Vertebrate organogenesis is initiated at sites that are often morphologically indistinguishable from the surrounding region. Here we have identified Pax9 as a marker for prospective tooth mesenchyme prior to the first morphological manifestation of odontogenesis. We provide evidence that the sites of Pax9 expression in the mandibular arch are positioned by the combined activity of two signals, one (FGF8) that induces Pax9 expression and the other (BMP2 and BMP4) that prevents this induction. Thus it appears that the position of the teeth is determined by a combination of two different types of signaling molecules produced in wide but overlapping domains rather than by a single localized inducer. We suggest that a similar mechanism may be used for specifying the sites of development of other organs.

Transforming growth factor-beta in human glomerular injury

Overexpression of the cytokine transforming growth factor-beta has been identified as the key mediator of chronic progressive kidney fibrosis in experimental and human kidney diseases. The renoprotective effects of angiotensin II blockade and low-protein diets have recently been linked to downregulation of transforming growth factor-beta production. Neutralizing the actions of transforming growth factor-beta by decorin gene therapy appears to be a highly effective new approach in the treatment of renal fibrosis.

Spontaneous regression of hepatocellular carcinoma

A 72-year-old Caucasian woman suffered from histologically-proven advanced hepatic cancer, for which she received no treatment. She had been a regular drinker for a long time. Serologic markers for hepatitis B and C were negative. In spite of her poor prognosis, she remained in good clinical condition and at 14 months of follow up the hepatocellular carcinoma could not be visualised any more radiologically. At that time the serum alpha foetoprotein concentration was normal. At present, 28 months after diagnosis, the patient is doing well and her tumour still appears to be in complete spontaneous remission.

Angiotensin II and L-arginine in tissue fibrosis: more than blood pressure

Angiotensin II (Ang II) blockade and restriction of dietary protein are thought to retard progression of renal disease primarily by reducing glomerular capillary pressure and thereby reducing injury to renal tissues. Relatively recent data suggest that both of these therapies may also act through pressure-independent mechanisms to reduce repair processes that follow tissue injury and which, if not self-limited, can continue to cause tissue fibrosis and organ failure. We review recent data suggesting that Ang II is a profibrotic molecule independent of blood pressure. Therapeutic actions of dietary restriction of total protein and restriction of the amino acid L-arginine that appear independent of pressure are also discussed. These effects are separated into those that reduce injury and those that reduce tissue repair. Finally, we ask whether the Ang II blockade or restriction of dietary protein could be more effective if they were aimed not only at limiting injury, but also at halting excessive repair.

Treatment of Graves' hyperthyroidism with radioiodine: results of a prospective randomized study

In this paper, we report the results of a randomized prospective study on radioiodine treatment in patients with Graves' hyperthyroidism. Complete data were obtained in group 1 from 98 patients 6 months after application of a standard activity of 15 mCi (555 MBq) of 131I and in group 2 from 107 patients who received a target dose of 100 Gy. In group 1, the overall success rate was 71%, but the results in the subgroups clearly were related inversely to the thyroid volume, ranging from 100% in patients with a thyroid volume < 15 mL to about 20% in those with a thyroid size of > 60 mL. In contrast, patients who received a target of 100 Gy showed very similar results, with success rates of about 40-50% in all but one subgroup. Only patients with a thyroid volume < 15 mL had a success rate of about 80%. But due to an incidental increase of uptake and/or effective half-time from the test to the therapy activity, this subgroup received a target dose of about 160 Gy. Additional calculation of the actual target dose in group 1 (standard activity) showed that, with a dose of 200 Gy, a success rate of 80% was obtained. Also, the thyroid volume reduction was related inversely to the target dose. Because the literature is abundant, only a restricted number of references are discussed that are either in agreement with our results or in sharp contrast to them. The reason for these discrepant results might be the difference in the scheme of pretreatment or the different alimentary iodine supply between, for example, Great Britain and the United States on the one hand and Germany on the the other hand.

[Treatment of euthyroid struma. Comparable volume reduction with 400 micrograms iodine, 100 micrograms levothyroxine combined with 100 micrograms iodine or individually dosed levothyroxine]

AIM

In patients with euthyroid goitre, the efficacy of treatment with 400 micrograms iodine and 100 micrograms levothyroxine combined with 100 micrograms iodine was compared to that of the previous standard of therapy, individually dosed levothyroxine.

PATIENTS AND METHODS

A total of 78 patients presenting with euthyroid diffuse goitre (> or = 25 ml) were prospectively enrolled, randomised and treated for 6 months. The course of thyroid volume was followed using thyroid volumetry.

RESULTS

Data of 69 patients were included in the final evaluation (57 women, 12 men, age 31 +/- 1 years, thyroid volume 31.5 +/- 1.4 ml, 23 per treatment group). In the patients treated with individually dosed levothyroxine, the thyroid volume decreased by about 39% (95%-confidence limit [CL]-31% to -41%). However, the volume reductions achieved in the patients treated with 400 micrograms iodine or 100 micrograms levothyroxine/100 micrograms iodine were not significantly different (p = 0.35, variance analysis, mono-iodine -34%, 95%-CL -29% to -43%, 100 micrograms levothyroxine/100 micrograms iodine -39%, 95%-CL -32% to -45%).

CONCLUSIONS

In patients with euthyroid diffuse goitre, treatment with mono-iodine or combination of levothyroxine with iodine should have principally the same status as the previous standard of therapy, individually dosed levothyroxine. In the view of the authors, its preferential treatment with mono-iodine appears most reasonable.

Dietary L-arginine in renal disease

The amino acid L-arginine is a substrate for at least three products involved extensively in tissue injury and fibrosis. L-arginine is metabolized to L-proline, a major constituent of the collagen that makes up fibrotic extracellular matrix. L-arginine is a precursor for polyamines, which are required for proliferative responses characteristic of many renal disease. L-arginine is also the sole substrate for generation of nitric oxide (NO) which, produced in large quantities by macrophages, has been implicated in tissue injury. On the other hand, NO produced in small quantities by endothelium is a critical vasodilator. Given the importance of elevated intraglomerular pressure in renal injury, it is perhaps not surprising that dietary L-arginine supplementation increase NO generation and is beneficial in reducing intraglomerular pressure and subsequent disease. Other data, based on the therapeutic effects of low protein diets, have suggested that L-arginine restriction limits NO-mediated glomerular injury and greatly reduces matrix accumulation, consistent with the idea that limitation of substrate effectively diminishes injurious NO levels, polyamine synthesis, and collagen production.

Staging urinary bladder cancer after transurethral biopsy: value of fast dynamic contrast-enhanced MR imaging

PURPOSE

To evaluate contrast enhancement patterns of urinary bladder cancer and surrounding structures and to evaluate a fast dynamic first-pass magnetic resonance (MR) imaging technique in tumor and node staging and in differentiation of urinary bladder cancer from postbiopsy effects.

MATERIALS AND METHODS

Sixty-one consecutive patients with histologically proved urinary bladder cancer were referred to undergo unenhanced and dynamic MR imaging 1-4 weeks after transurethral resection or biopsy. Subtraction and time (to beginning of enhancement) images were acquired.

RESULTS

Results with unenhanced T1- and T2-weighted images were compared with those obtained with the unenhanced images plus dynamic contrast material-enhanced single-section turbo fast low-angle shot (FLASH) images. Urinary bladder cancer started to enhance 6.5 seconds +/- 3.5 (standard deviation) after the beginning of arterial enhancement, which was 4 seconds earlier than most other structures (postbiopsy tissue, 13.6 seconds +/- 4.2). In differentiation of postbiopsy tissue from malignancy on the basis of the beginning of enhancement depicted on time and subtracted images, accuracy improved from 79% to 90% (P < .02) and specificity improved from 33% to 92% (not significant). Overall, tumor staging accuracy improved significantly from 67% to 84% (P < .01) by adding the turbo FLASH images.

CONCLUSION

Fast dynamic first-pass MR imaging, with at least one image acquired every 2 seconds, improved delineation of urinary bladder cancer, tumor staging, and detection of metastases.

[The prevention of the recurrence of endemic goiter. The efficacy of a once-a-week dose of 1.53 mg iodide]

OBJECTIVE

To investigate the efficacy of 1.53 mg iodide administered once weekly in the prophylaxis of goitre recurrence in patients with endemic euthyroid goitre after initial treatment to reduce the goitre size.

PATIENTS AND METHODS

46 consecutive patients who had undergone initial L-thyroxine, iodide or combined treatment were included in the prospective study. Thyroid volume was measured sonographically at the beginning as well as 6 and 18 months later. An increase in thyroid volume of more than 15% was taken as recurrence.

RESULTS

The study was concluded in 41 patients. During the prophylaxis mean thyroid volume increased from initially 21.7 +/- 9.9 ml to 22 +/- 10.9 ml after 6 months and to 24.5 +/- 12.1 ml after 18 months (P < 0.01). While thyroid volume remained unchanged in at least two thirds of patients, a recurrence occurred in 32% (n = 13; from initially 22.7 +/- 9.7 ml, to 26.3 +/- 11.3 ml at 6 months and to 29.7 +/- 12.3 ml at 18 months). In all patients with a recurrence a doubling of the iodide dosage to twice weekly 1.53 mg for 6 months reduced thyroid volume again (mean of 25.7 +/- 10.0 ml; P < 0.01).

CONCLUSIONS

In at least two third of patients a once-weekly dose of 1.53 mg iodide is a reliable means of preventing a recurrence of endemic euthyroid goitre, but in the remainder the same dose must be increased to twice weekly.

Prolonged enteroviral infection in a patient who developed pericarditis and heart failure after bone marrow transplantation

We described a patient who developed heart failure and pericarditis after bone marrow transplantation for a hematologic malignancy. The patient died of heart failure complicated by pneumonia. Despite extensive surveillance, an infectious cause for the heart failure was not found while he was alive. In addition, cultures of specimens obtained at autopsy did not reveal a cause for the heart failure. Enterovirus was detected by the polymerase chain reaction (PCR) in two samples of pleural fluid that were obtained 21 days apart while he was alive. After the patient died, enteroviral RNA was also detected in his lungs, liver, and spleen, indicating a generalized infection. Analysis of the PCR products revealed sequences sharing close homology with the coxsackie B-like group of enteroviruses. In addition to reporting this case, we review the literature regarding enteroviral infections after transplantation.

A randomized, prospective trial of stapled lung reduction versus laser bullectomy for diffuse emphysema

Two procedures (laser bullectomy and lung reduction surgery with staples) are currently available for the surgical treatment of patients with diffuse emphysema. We compared the efficacy of these two surgical approaches in 72 patients, aged 67 +/- 7 years (mean +/- standard deviation), who had diffuse emphysema scored as severe on computed tomography and severe fixed expiratory airflow obstruction. The patients were prospectively randomized to undergo either neodymium:yttrium aluminum garnet contact laser surgery (n = 33) or stapled lung reduction surgery (n = 39) by unilateral thoracoscopy. The operative mortalities were 0% and 2.5%, respectively. No significant differences were noted between the groups (p < 0.05) with respect to operating time, hospital days, or air leakage for more than 7 days. However, a delayed pneumothorax developed in six patients (18%) who had laser treatment (p = 0.005). The operations eliminated dependency on supplemental oxygen in 52% of the laser group and 87.5% of the stapled lung reduction group (p = 0.02). The mean postoperative improvement in the forced expiratory volume in 1 second at 6 months was significantly greater for the patients undergoing the staple technique (32.9% vs 13.4%, p = 0.01) than for the laser treatment group.

Reduction in thyroid volume after radioiodine therapy of Graves' hyperthyroidism: results of a prospective, randomized, multicentre study

The reduction in thyroid size in 92 patients treated with radioiodine for Graves' thyrotoxicosis was monitored by ultrasound volumetry. The patients were randomly treated with either a standard 131I activity of 555 MBq or an activity calculated to deliver a thyroid dose of 100 Gy. Within 1 year after radioiodine treatment, a remarkable volume reduction of about 71% (median) (quantile 25% (Q 25) = 49%, Q 75 = 82%, n = 67) was observed. The bulk of this reduction (median 57%, Q 25 = 21%, Q 75 = 74%, n = 92) was found within the first 6 months. Statistical analysis reveals that the effect was clearly related to the thyroid dose actually achieved during therapy. The median reduction obtained 6 months after radioiodine application was 45% for < 100 Gy, 56% for 100-200 Gy and 67% for > 200 Gy (n = 28, 39, 25 respectively). Twelve months after radioiodine application, the effect became less evident: 53%, 68% and 75% respectively (n = 17, 29, 21). The higher median thyroid dose actually achieved by standard than by calculated activity (215 Gy vs. 116 Gy) explains the more pronounced volume reduction in the standard group than in the calculated group; 60% vs. 47% 6 months (n = 47, 45) after radioiodine treatments and 74% vs. 66% 12 months (n = 31,36) after radioiodine application. The relative reduction in thyroid size was just as marked in patients with large thyroids as in those with small glands. The goitre prevalence (thyroid volume > 20 mL in women and > 25 mL in men) was reduced from 73% to only 16% 1 year after radioiodine treatment. In patients with a thyroid volume of more than 60 mL, the median pretherapeutic thyroid volume of 102 mL was reduced to 29 mL. In conclusion, radioiodine treatment in Graves' hyperthyroidism sufficiently reduces thyroid volume in a dose-dependent manner. The findings of this study demonstrate that radioiodine is also an attractive mode of therapy for Graves' patients with substantial thyroid enlargement.