The structure of a complex of human 17beta-hydroxysteroid dehydrogenase with estradiol and NADP+ identifies two principal targets for the design of inhibitors

BACKGROUND

The steroid hormone 17beta-estradiol is important in the genesis and development of human breast cancer. Its intracellular concentration is regulated by 17beta-hydroxysteroid dehydrogenase, which catalyzes the reversible reduction of estrone to 17beta-estradiol. This enzyme is thus an important target for inhibitor design. The precise localization and orientation of the substrate and cofactor in the active site is of paramount importance for the design of such inhibitors, and for an understanding of the catalytic mechanism.

RESULTS

The structure of recombinant human 17beta-hydroxysteroid dehydrogenase of type 1 (17beta-HSD1) in complex with estradiol at room temperature has been determined at 1.7 A resolution, and a ternary 17betaHSD1-estradiol-NADP+ complex at -150 degrees C has been solved and refined at 2.20 A resolution. The structures show that estradiol interacts with the enzyme through three hydrogen bonds (involving side chains of Ser142, Tyr155 and His221), and hydrophobic interactions between the core of the steroid and nine other residues. The NADP+ molecule binds in an extended conformation, with the nicotinamide ring close to the estradiol molecule.

CONCLUSIONS

From the structure of the complex of the enzyme with the substrate and cofactor of the oxidation reaction, the orientation of the substrates for the reduction reaction can be deduced with confidence. A triangular hydrogen-bond network between Tyr155, Ser142 and O17 from estradiol probably facilitates the deprotonation of the reactive tyrosine, while the conserved Lys159 appears not to be directly involved in catalysis. Both the steroid-binding site and the NADPH-binding site can be proposed as targets for the design of inhibitors.

Familial cavernous hemangioma with atypical neuroimaging

Three members of the same family were studied, all of whom had multiple intracerebral cavernous angiomas for which a dominant autosomal inheritance was hypothesised. The proband suffered from headaches, and physical examination revealed evident right hemiparesis. The second case started with a hemorrhagic cerebral stroke and the third was asymptomatic on neurological examination. Nuclear magnetic resonance (NMR), performed in two of the three cases, showed lesions whose number and extent were not radiologically characteristic of cavernous angioma. A cerebral biopsy of the proband enabled the diagnosis to be made. Despite the recent introduction of NMR, the nosological classification of familial forms can be difficult when the radiological lesions are atypical. In such cases, cerebral biopsy is not only a valid diagnostic aid, but is also indispensable for obtaining adequate genetic information.

Quantification of hepatitis C virus RNA by competitive amplification of RNA from denatured serum and hybridization on microtiter plates

The direct detection of hepatitis C virus (HCV) RNA by PCR is widely used to determine the presence of circulating virions. The most relevant limit of this approach is the lack of quantitative information about the viral titer. We report a technique of competitive amplification allowing the estimation of HCV RNA copy number in biological samples. We constructed a standard competitive RNA template containing only two point mutations compared with its wild-type counterpart. The competitor was added in titrated amounts to the target RNA, and the mixture was then reverse transcribed and amplified in the same reaction tube. The relative amounts of target and competitor were determined by differential hybridization on microtiter plates with nonradioactive probes. The evaluation of HCV RNA titer required a single coamplification with the competitor and could be read from a standard curve. Furthermore, this method proved suitable for amplification of HCV RNA directly from serum, thus avoiding the intrinsic variability of the RNA extraction step.

Selection of T lymphocytes in two rheumatoid arthritis patients defines different T-cell receptor V beta repertoires in CD4+ and CD8+ T-cell subsets

To study the selective pressures responsible for the expansion of T cells in rheumatoid arthritis, we constructed cDNA mini-libraries from purified CD4+ and CD8+ T cells prepared from peripheral blood and from synovial fluids of two rheumatoid arthritis patients. Comparison of these libraries by hybridization with specific probes indicated that V beta 2 and V beta 8 transcripts are selectively enriched in the CD4+ synovial fluid lymphocyte population, while V beta 4 was over-represented among both the CD4+ and CD8+ subsets. The enrichment of V beta 14 and V beta 17 observed in synovial fluid T cells of one patient was, however, selectively confined to the CD8+ T-cell subpopulation. Sequence analysis of several V beta 2, V beta 4 and V beta 8 clones, derived from CD4+ cells, revealed a high degree of heterogeneity in the V beta-D beta-J beta junctions, while a more biased utilization of J segments and a more restricted junctional heterogeneity were observed in V beta 4, V beta 14 and V beta 17 clones derived from CD8+ cells. These data suggest that the disease may be induced by the initial activation of a rather heterogeneous population of T-helper cells that are later responsible for the expansion of a more restricted pool of highly specific effector lymphocytes.

[Cranial fractures during growth. An analysis of the authors' personal cases and therapeutic management of such childhood pathology]

Growing skull fractures are a rare complication of head injury with a dome fracture. The cases described in literature highlight a higher frequency of this pathology in children under than over three years of age. The authors describe 4 personal cases, underlying the clinical, diagnostic and therapeutic aspects. The aetiological hypothesis of a dural tear and its anatomic-pathological evolution are investigated. The surgical technique of dural and bony repair is also discussed. The authors conclude that this complication must be recognized early in order to obtain very good results after surgical therapy.

DNA enzyme immunoassay: a rapid and convenient colorimetric method for diagnosis of cystic fibrosis

Genetic analysis of inherited diseases has been greatly facilitated by new approaches, involving genomic DNA amplification by the polymerase chain reaction (PCR), followed by hybridization with wild type-specific or mutation-specific oligonucleotide (MSO) probes. The main advantage of these methods is that they allow easy detection of point mutations starting from minimal amounts of biological materials. These techniques, however, require procedures which are not well suited to large-scale screening or use in routine laboratories. The development of dedicated kits to perform these tests efficiently in clinical laboratories is an important current issue. We developed a new non-radioisotopic assay to reveal specifically DNA-DNA hybrids between amplified DNA and MSO probes, and applied it to the detection of two mutations causing cystic fibrosis. The detection of hybrids is achieved by means of an anti double-stranded DNA antibody, in a format which is designed as a colorimetric assay resembling a common enzymatic immunoassay (EIA). The assay detects the hybridization event, independent of the nucleic acid sequences involved in the formation of the specific hybrids, and can be used with any combination of target DNA and probes. Therefore, this test represents a significant improvement for the clinical use of the polymerase chain reaction in the diagnosis of inherited diseases.

Irreversible respiratory failure in an achondroplastic child: the importance of an early cervicomedullary decompression, and a review of the literature

The authors report the case of a girl with achondroplasia suffering from a progressively worsening hypotonic quadriparesis. CT scan showed slight dilatation of ventricular and subarachnoid spaces, with well-defined evidence of cortical sulci and gyri. This aspect was compatible with the diagnosis of macrocrania and megalencephaly (CP being 51 cm). The foramen magnum was narrowed, the transverse diameter measuring 15 mm and the 50th percentile being, for age, 26 mm. Somatosensory evoked potentials (SEPs) revealed bilaterally prolonged interpeak latencies Erb-N13, slowing of central conduction time N13-N20 from right median nerve stimulation, and block from left median nerve. The suspicion of cervicomedullary compression was confirmed by MRI, showing a very marked stenosis with compression exerted by the odontoid process. Further, a stenotic cervical canal and optic nerves verticalization were manifest. The patient underwent neurosurgical decompression by suboccipital craniectomy and cervical-C1 laminectomy. In spite of treatment, both neurologic and respiratory problems (rapid, shallow and almost abdominal breathing) were unchanged. The girl died 4 1/2 months later. The authors emphasize the important role of SEPs in detection of cervicomedullary compression in achondroplastic children and also stress the necessity of an early surgical treatment as the only condition for possible clinical improvement and/or full recovery.

Spontaneously healed vein of Galen aneurysms. Clinical radiological features

Vein of Galen aneurysms demonstrate a high tendency to thrombose, as extensive thrombophlebitis of the dural sinuses and deep venous system occurs frequently. This may be explained by the frequent detection of venous anomalies and retention of embryonic venous patterns such as the median prosencephalic vein. Twenty-one cases were reviewed (19 from the literature, 2 of our own cases): no typical syndrome for thrombosed aneurysm of the vein of Galen could be found; therefore, a preliminary diagnosis of clotted vein of Galen aneurysm was made in only half the cases. In all the remaining ones, pineal or III ventricle masses were suspected. Nevertheless, crescentic rimlike calcifications in the region of the vein of Galen can be found in 50% of cases. Only in half of the cases did angiography demonstrate the malformation filled by contrast medium, while in the remaining cases not only the aneurysm but also the deep Galenic venous system failed to opacify. Computed tomography and magnetic resonance scans demonstrated masses with high density/intensity values, with varying degrees of calcification. Knowledge of this pathological entity is important in order to avoid unnecessary surgical procedures.

Cerebral cavernous malformations (cavernomas) in the pediatric age-group

Cavernomas are vascular malformations composed of a compact mass of sinusoidal-type vessels that are immediately contiguous with one another and have no intervening parenchyma. Cavernous malformations were previously held to be a rare pathology occurring predominantly in adults. New neuroradiological techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) demonstrate, on the contrary, that these lesions are also more frequent during childhood than was previously thought. In our institution we observed 17 cases of cavernous malformations in patients aged between 18 months and 16 years, 16 of whom were diagnosed after 1982. In 4 of these cases there was a documented familial history; in 2 multiple malformations were present. The most common site was the subcortical frontal region, but in 1 case the malformation was located in the pineal region. The most frequent (in 12 cases) initial symptom was hemorrhage, with the characteristics of an intracerebral hematoma. In 4 cases the initial symptom consisted of epileptic fits and 2 of these patients subsequently suffered hemorrhage. In one case the symptoms observed were those of an expansile process. All our patients underwent cerebral angiography and only in 1 case did this show a vascular abnormality. CT, performed in 16 patients, gave positive results in all cases. MRI, performed in 12 patients, gave highly significant images in all cases. Radical surgical removal of the malformation was performed in 15 of the 17 patients, and the results can be considered excellent in the majority of cases. Cavernous malformations are, therefore, more frequent lesions than had previously been thought, especially in pediatric patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Transient focal leukoencephalopathy following intraventricular methotrexate and cytarabine. A complication of the Ommaya reservoir: case report and review of the literature

A 14-year-old boy, suffering from acute lymphoblastic leukemia with meningeal involvement, was treated with intraventricular methotrexate and cytosine arabinoside, administered via an Ommaya reservoir (OR). Three months later, right occipital headache, vomiting, and lethargy appeared. Cerebrospinal fluid specimens showed increased proteins and a right frontal slow-wave focus was evident on the EEG recording. The computed tomography scan revealed white matter hypodensity within the right frontal and rolandic regions. After injection of medium contrast, an abscesslike hyperdensity appeared, surrounding both a well-placed cannula tip and the right frontal horn of the lateral ventricle. Brain swelling and shift signs were also evident. Nine cases of focal methotrexate leukoencephalopathy have been previously reported, and in six of these there was a misplaced OR cannula tip. The focal methotrexate leukoencephalopathy seems to be related to the neurotoxicity of the drugs administered, and may also exist with a well-placed OR cannula tip. Immediate removal of the catheter may be associated with a benign evolution.

Medical treatment of senile cataract: clinical investigation of bendazac-lysine using objective and subjective methods

A modified Zeiss slit lamp coupled with a digital image-processing system was used to evaluate objectively changes in lens transparency over 1 year at 4-month intervals in 150 eyes of 92 patients affected by early senile cataract. A total of 59 patients were treated daily with 1.5 g bendazac-lysine, and 33 patients constituted the control group. At follow-up, visual acuity was also tested using Snellen letter charts at variable contrast to provide an additional parameter closer to traditional methods. Results indicate that the minimal angle of resolution at 10% contrast (MAR10) and the mean gray-level value of the lens image obtained by retroillumination (MLR) are sensitive to early changes in lens transparency. Using MAR10 as a parameter, the control group showed a significant, progressive worsening of the lens status over 12 months, whereas the treated group exhibited no significant changes. MRL indicated the same behaviour as MAR10, although lens damage was detected later in the control group. The results show that bendazac-lysine may delay the formation of lens opacities.

Genetic mapping of the Saccharomyces cerevisiae DNA polymerase I gene and characterization of a pol1 temperature-sensitive mutant altered in DNA primase-polymerase complex stability

The cloned DNA polymerase I gene has been used to map the POL1 locus on the left arm of chromosome XIV, between MET4 and TOP2. Temperature-sensitive mutants in POL1 have been obtained by in vitro mutagenesis of the cloned gene and in vivo replacement of the wild-type allele with the mutated copy. Physiological and biochemical characterization of one temperature-sensitive mutant (pol1-1) shows that cells shifted to the non-permissive temperature can complete one round of cell division and DNA replication before they arrest. Analysis of DNA polymerase I in crude extracts and in partially purified preparations indicates that the pol1-1 mutation results in a conformational change and affects the stability of the DNA primase-polymerase complex.

[Intracranial aneurysms and subarachnoid hemorrhage in children and adolescents]

42 cases concerning symptomatic intracranial circulation aneurysms and spontaneous SAH have been observed by the authors during the period 1965-1984; 37 of them were treated from 1970 on. This group represents 2.6% in the number of patients treated for SAH during the above mentioned period in the series of Pavia and Verona Neurosurgery. In 7 cases angiography did not evidence any malformation responsible for the hemorrhage. These cases have been defined as "sine materia" SAH. In 33 cases was documented the presence of an intracranial aneurysm as responsible for the hemorrhage. In the 2 remaining cases was found an aneurysm that even if unbroken had manifested itself. In 4 cases aneurysms were mycotic ones. The most frequent sites of aneurysms have been the carotid artery bifurcation and the middle cerebral artery 24% each one followed by the anterior communicating artery 21%. 5 patients were younger than 4 years and each one had peculiar clinical features. The 37 remaining patients were older than 9 years and have been subdivided in 2 groups: 16 patients from 9 to 15 years old in who the most common site of the aneurysm was the carotid artery bifurcation and the middle cerebral artery (31%) and the frequency of intracerebral hematoma was 50%; 21 patients from 16 to 20 years old in who the most common site of the aneurysm was the anterior communicating artery (33%) and the presence of an intracerebral hematoma was markedly inferior (14%). 23 of the 35 patients having an aneurysm underwent a surgical procedure for its exclusion. Operative mortality rate was nearly 5% and morbidity rate was nearly 12%. 5 patients who were in agony when admitted were not operated; 5 patients had a conservative therapy and in 2 of them an angiography performed at distance from the hemorrhage revealed the disappearance of the aneurysm. Clinical disturbances bound to ischemic phenomenons by cerebral vasospasm were observed in only 3 patients--all of them older than 17--in who a CT scan had showed a conspicuous cisternal blood suffusion. In 13% of cases appeared hydrocephalus and only in 3 cases was necessary to perform a shunt. The global results of therapy have been significantly better than in adults having 74% of good results and 19% of deaths. This prognostic improvement is probably due both to the well known recovery from neurological failure in young patients and to the very low incidence of ischemic manifestations from vasospasm in this range of age.

Intracranial aneurysms and subarachnoid hemorrhage in children and adolescents

Thirty-eight cases of symptomatic cerebral aneurysms or spontaneous subarachnoid hemorrhage in children and adolescents were observed from 1965 to 1984; 33 cases were treated from 1970 to date. This group represents 2.6% of the total number of patients with subarachnoid hemorrhage treated at our institute in the same period. The cause of subarachnoid hemorrhage was unknown in 7 cases; an intracranial aneurysm had ruptured in 29 cases, and was unruptured but symptomatic in 2 remaining cases. Three aneurysms were mycotic. The most frequent aneurysmal locations were the internal carotid bifurcation and the anterior communicating artery; peripheral branches of the middle cerebral artery were also a relatively common location. Four patients were 3 years of age or younger: each presented peculiar clinical features, and 3 of the 4 had middle cerebral artery aneurysms. The remaining 34 patients were all above 9 years of age. Two groups were identified: (a) in 14 patients between 10 and 15 years of age, the aneurysm was most commonly at the internal carotid bifurcation (37%), and an intracerebral hematoma was observed in 50% of these cases; (b) in 20 patients between 16 and 20 years of age, the most common aneurysmal location was the anterior communicating artery (35%), and intracerebral hematomas were rare (10% of cases). Among patients with aneurysms, 19 underwent surgical exclusion by clip, with 10% morbidity and 5% mortality; 5 patients in moribund conditions were not operated on; 5 patients were conservatively treated; in 2 patients the aneurysm had disappeared at a second angiography.(ABSTRACT TRUNCATED AT 250 WORDS)

Spontaneous disappearance of a large middle fossa arachnoid cyst

A case of a large middle fossa arachnoid cyst that spontaneously disappeared is reported. The possible mechanisms involved in the "natural cure" of this lesion and the indications for surgical versus conservative treatment of middle fossa arachnoid cysts are discussed.

Childhood cerebrovascular diseases not associated with vascular malformations

Of 76 patients in the pediatric age group suffering from cerebrovascular diseases treated in the years 1970-1983, 26 patients (34%) did not harbor intracranial vascular malformations (aneurysms or arteriovenous malformations). Two groups of patients were identified: (a) those suffering from a spontaneous intracranial hemorrhage (16 cases); (b) those suffering from an ischemic stroke (10 cases). Of those with spontaneous intracranial hemorrhage, 10 patients underwent surgery and evacuation of the hematoma. In 2 cases the hematoma was located in the posterior fossa, in 1 case in the upper brain stem, and in 3 cases in the basal ganglia; in the remainder the hematoma was supratentorial. Two patients died soon after the hemorrhage. Eight of the surviving patients completely recovered. In those with ischemic stroke, none suffered from congenital heart disease, a well-known predisposing factor. In this second group 1 patient died and 9 survived. Only one patient showed complete recovery. The data indicate that a hemorrhagic stroke is more common than an ischemic stroke in a child presenting with acute onset of hemiparesis and/or loss of consciousness: thus the value of CT scan as the first diagnostic procedure is clear, owing to the possibility of emergency surgical treatment. In children with ischemic strokes, a complete laboratory/clinical evaluation should be undertaken in order to exclude preexisting heart disease, coagulation disorders or lipoprotein abnormalities, and less common systemic diseases.

Intracranial arteriovenous malformations in the pediatric age: experience with 24 cases

24 patients below 16 years of age with intracranial arteriovenous malformations are considered. Presenting history has been constituted mainly by intracranial hemorrhage, followed by epilepsy and hydrocephalus. The utility of angiography and CT scan is stressed, especially for preoperative evaluation. The arteriovenous malformation was located in noncritical cortical areas in 7 cases, in critical cortical areas in 6 cases, in the midline structures or in the basal ganglia in 8 cases, in the posterior fossa in 2 cases, and was only dural in 1 case. Complete surgical resection of the lesion has been carried out in 18 cases, and embolization in 1 case. The operative microscope, induced hypotension, and the 'backward technique' have been very useful during surgery. Following the operation, good results have been achieved in 83% of cases; mortality has been 11%. In most cases epilepsy has shown improvement after surgery. It is concluded that direct surgical extirpation of the angioma is the treatment of choice for pediatric patients, even in the presence of epilepsy alone.

Midline giant arterio-venous malformations in infants

Three rare cases of giant midline arterio-venous malformations are presented. The first case is an infant girl with a vein of Galen malformation, who died from a subarachnoid haemorrhage a few weeks after shunt insertion for the control of hydrocephalus. The second case is an infant girl with a massive dilatation of the superior longitudinal sinus, who died from acute cardiac decompensation following direct surgery on the malformation. The third case is an infant boy with very large bilateral angiomas of the basal ganglia, who was not treated surgically. Some unusual features of these cases are discussed. Anatomically, the lesion can be quite different from a typical vein of Galen malformation. Clinically, the presence of cardiac failure and hydrocephalus is not always the case, and the possibility of a subarachnoid haemorrhage must be considered. For these reasons, infants with giant midline AVMs should be treated individually, balancing various considerations.

Traumatic extradural haematomas in children: experience with 62 cases

Sixty-two children with traumatic extradural haematomas are considered According to the clinical history presented--often atypical--and to the grade of neurological impairment, patients have been divided into different clinical groups. Nearly 50% of patients sustained a minor injury, and 26% did not lose consciousness after trauma. Twenty-four per cent of patients did not show fractures on skull X-rays. Atypical location of the haematoma was noted in 22 cases, mainly in the anterior fossa (19 cases). Sixty patients were operated on, while two patients were conservatively treated, owing to the limited size of the haematomas and to the absence of neurological deficits. Associated brain lesions were discovered at surgery in 40% of cases. The overall mortality rate has been 17%, the operative mortality rate 14%. The morbidity rate has been 6%, with 3% of patients presenting severe disability. Morbidity and mortality have been shown to be affected by age--with better prognosis in patients under 10 years of age, by the clinical history presented, by the preoperative conditions, and, mainly, by the presence of associated brain lesions. As regards location, frontal haematomas have shown a better prognosis and a slower course than convexity haematomas. Finally, prognosis of extradural haematomas in children has improved to some extent in the last years with the advent of the CT scan, possibly due to speed and accuracy of diagnosis.

Treatment of medulloblastoma in children: long-term results following surgery, radiotherapy and chemotherapy

Forty-seven children with histologically confirmed medulloblastoma are considered. Forty-five cases were surgically by direct approach to the tumour, while two cases were treated only with a shunt. A shunt was inserted preoperatively in 14 cases, postoperatively in 4 cases. Surgical resection was total or subtotal in 52% of cases, partial in 35%, and limited to a biopsy in 13%. Radiation treatment to the entire neuraxis was done in 37 cases: 10 of these cases received additional chemotherapy--mostly with CCNU--as primary treatment for medulloblastoma. Ten patients died within 30 days after surgery. Twenty-two patients died months after treatment, mainly from tumour recurrence (19 cases). One patient was lost to follow-up. Thirteen patients are survivors from 10 months to 20 years after treatment. As a whole, the one year survival rate has been 67%, 3 year survival 43%, and 5 year survival 27%. Complications affecting prognosis have been presented by tumour recurrence and metastases. CSF shunting and lack of prophylactic irradiation to the cerebral hemispheres have been considered responsible for the high incidence of supratentorial metastases in our series. Factors influencing prognosis have been the extent of tumour resection and association of primary chemotherapy with radiotherapy. Within 3 years after surgery survival has been 52% in cases with total resection against 31% in cases with partial resection of tumour. As regards chemotherapy, 3 year survival has been 60% for patients with combined treatment (chemo- and radiotherapy) against 37% in patients with radiotherapy alone. It is concluded that the best results in children with medulloblastoma are achieved by a radical resection, associated with a combined primary treatment of radiotherapy and chemotherapy.

An unusual case of meningeal gliomatosis

A case of meningeal gliomatosis following a primary spinal cord tumor is reported. The clinico-pathological features of this unusual extension of a spinal glioma are described. The rare incidence of this malignancy and its occurrence in young patients only are stressed. The possible pathophysiological events leading to the diffuse dissemination of the neoplastic cells are discussed.

[Extracranial metastases from medulloblastoma: report of four cases (author's transl)]

Four cases of bone and pulmonary metastases of medulloblastoma histologically diagnosed and with an exhaustive clinical-radiological and scintigraphic documentation, are described. In three patients, one of which non operated, the metastases of the osteolytic and osteoblastic type affected diffusely the skeleton; in the fourth patient the bone lesions were associated with a single pulmonary metastasis. The modality of metastatic spread and the clinical course of the illness in the diagnostic and therapeutic aspects are discussed.