Vascular endothelial growth-permeability factor in granulation tissue of chronic subdural haematomas

BACKGROUND

Vascular Endothelial Growth/Permeability Factor (VEG/PF) has been correlated with angiogenesis and vascular leakage in diverse pathological conditions of the brain. On the other hand, neoformation of capillaries and vascular hyperpermeability have been related to progressive enlargement of chronic subdural haematomas (CSDH). The purpose of the present study is to verify the presence of VEG/PF in tissue of CSDH, with the hypothesis that neovascularization and vascular hyperpermeabitity in CSDH can be related to the presence of this cytokine.

METHODS

Immunohistochemical studies and Reverse Transcription Polymerase Chain Reaction (RT-PCR) analysis were performed in the neomembranes of 12 CSDH to verify presence of VEG/PF in this tissue.

FINDINGS

Strong expression of VEG/PF was immunohistochemically disclosed in neomembranes of CSDH, as well as in inflammatory cells currently infiltrating this tissue. Furthermore, RT-PCR studies showed the presence of VEG/PF in all the studied samples.

INTERPRETATION

These findings suggest a role for inflammatory cells, currently present in the granulation tissue of CSDH, in the release of VEG/PF and in the enlargement of these lesions, stating the possibility of a new therapeutic approach to CSDH, based on blocking the physiological effects of VEG/PF.

Imbalance between apostain expression and proliferative index can predict survival in primary glioblastoma

BACKGROUND

Cell proliferation and cell death are opposing processes in tumour growth, with tumour progression reflecting the balance between proliferating and apoptotic cells. The purpose of the present study is to verify the hypothesis that an imbalance between apoptosis and proliferation can predict survival in patients with primary glioblastoma.

METHODS

After the immunohistochemical study of Apostain and MIB-1 expression, the index of apoptosis (AI), the index of proliferation (PI), and the ratio AI/PI was recorded for each tumour specimen, in a series of 32 primary glioblastomas. Studies of correlation between AI and PI, between AI and survival, between PI and survival, and between the ratio AI/PI and survival, were performed using the Spearman rank correlation test. Furthermore, a comparative study of survival was performed for subgroups of patients with ratio AI/PI greater or lesser than 1, using the log rank test.

FINDINGS

In the present series, values of AI and PI showed a wide distribution, with a mean +/- SD of 8.16 +/- 7.2, and of 12.69 +/- 21.1, respectively. The values for the ratio AI/PI ranged between 0.01 and 6.03 (mean +/- SD: 1.44 +/- 1.60). Statistical study failed to obtain correlation between AI and PI. Survival of patients not correlated with AI neither with PI. The ratio between AI and PI did not correlate with survival either. Nevertheless, when survival for the subgroups of patients showing a ratio AI/PI greater or lesser than 1 was compared, a significant difference was found (p: 0.02). Survival ranged between 50 and 81 weeks (mean of 58.5 +/- 11.05 weeks) for the 12 cases showing a ratio AI/PI greater than 1, and it ranged between 8 and 85 weeks (mean: 38.20 +/- 25.37 weeks) for the 20 cases showing a ratio AI/PI lesser than 1.

INTERPRETATION

Our present results suggest that a clear imbalance between cell proliferation and apoptosis can predict outcome in patients operated on for a primary glioblastoma.

Antitumoral effect of irinotecan (CPT-11) on an experimental model of malignant neuroectodermal tumor

Irinotecan (CPT-11) is a topoisomerase I inhibitor with antitumor activity on a wide variety of neoplasms in several preclinical studies, but it showed poor efficacy in patients with nervous system tumors. We have carried out an experimental study in order to evaluate the effect of CPT-11 on the growth of a subcutaneously implanted malignant neuroectodermal tumor, after administration by different routes. The results showed that CPT-11 administration by intraperitoneal injections (at dose 10 mg/kg, 5 days per week, for 2 weeks, followed by 7-days rest period--one course--to a total of two courses) had no significant antitumor effect. Nevertheless, continuous infusion by intraperitoneal osmotic minipump over 28 days (at an infusion rate of 4.4 microg/h) showed a significant delay in tumor growth in 4 weeks of the implantation. The best antitumor effects were observed after CPT-11 intratumoral administration (at dose of 5 mg/kg, 5 days per week, for 2 weeks, followed by 7-days rest period, to a total of three courses) reaching tumor regression in the treated animals. These results suggest the utility of CPT-11, by means of intralesional administration, on malignant tumors of the nervous system.

Expression and significance of vascular permeability factor in tumour infiltrating lymphocytes of brain metastases

BACKGROUND

Recently, vasogenic edema has been related to the expression of vascular permeability factor (VPF) by tumour cells in brain metastases. On the other hand, expression of VPF has been reported in inflammatory cells. Keeping in mind the current presence of tumour-infiltrating lymphocytes (TIL) in brain metastases, our objective is to study the expression and significance of VPF in TIL-cells from specimens of brain metastases.

METHOD

Tumour samples from 16 brain metastases associated with peritumoural edema were immunohistochemically studied for demonstration of VPF. The degree of VPF-expression by tumour cells and TIL was determined, and correlated with the degree of peritumoural edema.

FINDINGS

Our present results show that, independently of the VPF-positivity expressed by the tumour cells, VPF-expression is a constant finding in TIL-cells of brain metastases, and correlated with the amount of peritumoural edema.

INTERPRETATION

Our present findings suggest a role for TIL-cells in the development of vasogenic edema associated with brain metastases.

Genes and peptides from the scorpion Centruroides sculpturatus Ewing, that recognize Na(+)-channels

Sixteen different genes were cloned from the venomous glands of Centruroides sculpturatus Ewing using RNA extracted from scorpions collected in Tucson, Arizona. Based on the amino acid sequence similarities of the proteins coded by these genes, all together there are 22 different structural components in this venom, thought to be specific for Na(+)-channels. The genes reported contain signal peptides with 19 amino acid residues followed by mature peptides of 63-66 amino acid residues in length. One of them correspond to toxin I (CsEI), a known scorpion toxin specific for Na(+)-channels. Four different genes are almost identical to variant 1 (Csv1), presenting only one amino acid change from the original protein. For variant 2 (Csv2) four related genes were found, with only one amino acid change in their primary sequences. Another gene resembles to variant 3 (Csv3, the best known Centruroides sculpturatus toxin), with only three amino acid changes in their primary sequences. Additionally, two genes show variations only on the nucleotide sequence at level of the signal peptides, and several genes clearly show sequences that suggest post-transcriptional modifications, during the maturation process. A phylogenetic tree was generated with the primary structures available and three main divergent branches were found.

Prognostic significance of the endothelial surface in low-grade resected oligodendrogliomas

The importance of angiogenesis as a prognostic factor in brain tumours has recently been reported. In this study, we analysed the long-term prognostic significance of a morphometric score expressing the endothelial area for every 1000 tumour cells, in tumour tissue from 26 patients with a low-grade oligodendroglioma that has been treated surgically and irradiated, and has a MIB-1 labelling index (MIB-1 LI) of less than 1%. In each tumour, a vascular endothelial surface index (VESI) was determined as the CD-34 immunostained endothelial area in micron 2 per 1000 tumour cells. Patients with a VESI of less than 15 (n = 12) showed a survival at 5 and 10 years of 100 and 71%, respectively, versus a survival of 50 and 0% for patients presenting a VESI greater than 15 (n = 14); p < 0.05). Our present findings suggest the usefulness of VESI as a long-term prognostic pathological factor in low-grade oligodendroglioma.

Functional recovery in chronic paraplegic rats after co-grafts of fetal brain and adult peripheral nerve tissue

BACKGROUND

In recent years, experimental studies have sought some type of functional improvement in traumatic paraplegia by transplanting neural tissue into the injured spinal cord. The aim of this work is to study the possibility of functional recovery in chronic paraplegic rats after co-transplantation of fetal cerebral tissue and adult peripheral nerve tissue.

METHODS

Seventy adult female Wistar rats were subjected to spinal cord injury at the T6-T8 level, causing complete paraplegia. Three months later, in 50 rats (grafted group) the injured spinal cord tissue received a graft of fetal brain cortex associated with crushed adult peripheral nerve. All the animals (grafted and control groups) were subjected to daily rehabilitation procedures from the first week after the injury, and evaluated weekly for motor and sensory recovery. Statistical analysis of different behavioral data between control and grafted animals was performed using the Kruskal-Wallis ANOVA and the nonparametric Wilcoxon test.

RESULTS

Between 8 and 12 months after transplantation, progressive signs of functional recovery were observed in the grafted animals, associated with an increase in muscle mass in the lower extremities, findings that were significantly different from those in nongrafted animals (p < 0.05). At this time, donor cerebral tissue is integrated into previously injured spinal cord and results in formation of bundles of nerve fibers that emerge from the area of the transplant and surround the spinal cord beneath the lesion.

CONCLUSIONS

Delayed co-transplantation of fetal cerebral tissue and peripheral nerve tissue can be used to achieve anatomical remodeling and long-term functional recovery in rats rendered paraplegic as result of severe spinal cord injury. These findings support the possibility of functional recovery after chronic traumatic paraplegia.

Presence and significance of CD-95 (Fas/APO1) expression after spinal cord injury

OBJECT

A glycoprotein, CD95 (Fas/APO1) is widely considered to be implicated in the development of apoptosis in a number of tissues. Based on the hypothesis that apoptosis is related to cell death after spinal cord injury (SCI), the authors studied the presence and distribution of CD95 (Fas/APO1)-positive cells in injured spinal cord tissue for the purpose of determining the significance of this protein during the early phases of SCI.

METHODS

The presence and distribution of cells showing positive immunostaining for CD95 (Fas/APO1) were studied 1, 4, 8, 24, 48, and 72 hours and 1, 2, and 4 weeks after induction of experimental SCI in rats. Studies were conducted using a monoclonal antibody to the CD95 (Fas/APO1) protein. Positivity for CD95 (Fas/APO1) was observed in apoptotic cells, mainly in the gray matter, 1 hour after trauma, and the number of immunostained cells increased for the first 8 hours, at which time the protein was expressed in both gray and white matter. From 24 to 72 hours postinjury, the number of immunostained cells decreased in the gray matter, but increased in the white matter. From then on, there were fewer CD95 (Fas/APO1)-positive cells, but some cells in the white matter still exhibited positive immunostaining 1 and 2 weeks after injury. At 4 weeks, there remained no CD95 (Fas/APO1)-positive cells in injured spinal cord.

CONCLUSIONS

These findings indicate that CD95 (Fas/APO1) is expressed after SCI, suggesting a role for this protein in the development of apoptosis after trauma and the possibility of a new therapeutic approach to SCI based on blocking the CD95 (Fas/APO1) system.

Increased UV light sensitivity in transgenic Drosophila expressing the antisense XPD homolog

The XPD gene is required for excision repair of UV-damaged DNA and is an important component of nucleotide excision repair (NER). Mutations in the XPD gene generate the cancer-prone syndrome xeroderma pigmentosum, Cockayne's syndrome, and trichothiodystrophy. XPD is a component of the TFIIH transcription factor, which is essential for RNA polymerase II elongation. In this work, we report the construction of transgenic flies overexpressing the antisense RNA of the Drosophila melanogaster XPD homolog (DmXPD). These flies show an increased sensitivity to UV radiation compared with the wild-type. This is an expected phenotype if the XPD function is affected and indicates that the antisense approach may be an alternative in the study of TFIIH functions in Drosophila.

Prognostic significance of endothelial surface score and MIB-1 labeling index in glioblastoma

The aim of this study is to investigate the usefulness of a vascular endothelial surface score (VESS) and MIB-1 labeling index (MIB-1 LI), in a defined series of glioblastomas, as biological markers with prognostic significance of survival. Tumor tissue and survival were studied in a series of 38 patients with glioblastoma, previously treated by surgical resection and radiotherapy. For each tumor, immunohistochemical and morphometric studies were performed in order to study MIB-1 LI, and VESS, expressed as the CD-34 immunostained endothelial surface per 1000 tumor cells. The survival for the entire patient population of the series was 48.1+/-14.1 weeks, and the mean VESS for the tumors of the series ranged from 16.7 to 107 microm2 per 1000 tumor cells (mean: 38.7+/-18.2). Factors such as age or MIB-1 LI were not significatively associated with survival, but the median survival for the 18 patients with a VESS less than 35 was 50.7+/-3.7 weeks, versus 45.9+/-2.8 weeks for the 20 patients showing a VESS higher than 36 (p < 0.05). Our present results suggest that tumor VESS, expressed as the CD-34 immunostained endothelial surface per each 1000 tumor cells, may have usefulness, as angiogenic-related factor influencing survival, in patients with glioblastoma.

[Early cellular immune response in experimental labyrinthitis: immunohistochemical study]

Labyrinthitis ossificans is a recently recognized entity with the extending cochlear implant surgery. Up to date there are not so many studies of the cellular response leading the organization of the inflammatory reaction within the cochlea. Immunemediated labyrinthitis is a valid experimental model that allow the knowledge of the cellular infiltration mechanisms within the cochlea. The inner ear communicates with systemic immunity via the circulation by the passage of cells through the spiral modiolar vein (SMV) and its collecting venules in the scala tympani. Inflammatory reaction within the cochlea lead to the formation of fibrotic tissue and bone (osteoneogenesis) inside it and injuring the neurosensory organs of hearing and balance. To test which cells are proliferating early in an inflammatory response, an animal model of Keyhole limpet haemocyanin (KLH) induced labyrinthitis was utilized, showing a granulomatous lesions not previously reported in this experimental model.

Fractal-like Aggregates: Relation between Morphology and Physical Properties

A number of modern technological applications require a detailed calculation of the physical properties of aggregated aerosol particles. For example, in probing soot aerosols by the method called laser-induced incandescence (LII), the soot clusters are suddenly heated by a short, powerful laser pulse and then cool down to the temperature of the carrier gas. LII sizing is based on rigorous calculation of the soot aggregate heat-up and cooling and involves prediction of laser light absorption and energy and mass transfer between aggregated particles and the ambient gas. This paper describes results of numerical simulations of the mass or energy transfer between the gas and fractal-like aggregates of N spherical particles in either the free-molecular or continuum regime, as well as the light scattering properties of random fractal-like aggregates, based on Rayleigh-Debye-Gans (RDG) theory. The aggregate geometries are generated numerically using specially developed algorithms allowing "tuning" of the fractal dimension and prefactor values. Our results are presented in the form of easily applicable scaling laws, with special attention paid to relations between the aggregate gyration radius and the effective radius describing various transport processes between the aggregates and the carrier gas. Copyright 2000 Academic Press.

Prognostic significance of clinical and angiogenesis-related factors in low-grade oligodendrogliomas

BACKGROUND

Keeping in mind that oligodendrogliomas have unpredictable biological behavior, the aim of this study is to investigate the prognostic significance of VEGF expression and microvessel density in a homogeneous series of low-grade oligodendrogliomas.

METHODS

For this study 36 patients with a low-grade oligodendroglioma treated by surgical resection and radiotherapy were selected. At the time of surgery, in all cases the Karnofsky Performance Scale (KPS) score was more than 70, and the study of the resected tumor disclosed a Ki-67/MIB-1 labeling index (MBI-1 LI) less than 1%. In this homogeneous series, immunohistochemical studies were performed using monoclonal antibodies against VEGF in order to study the expression of this cytokine, and against vascular endothelial CD-34 antigen, in order to identify microvessels.

RESULTS

Our results show that in contrast to low-grade astrocytomas, low-grade oligodendrogliomas lacked immunoreactive VEGF. Oligodendrogliomas with low vascular density (less than 20 microvessels per microscopical field, at 200 x) or high vascular density (more than 100 microvessels per field, at 200 x) were identified, but this factor had no influence on the survival rate of patients. On the other hand, analysis of the present series showed that clinical factors, such as age or extent of surgical resection, were not significantly associated with survival.

CONCLUSIONS

In contrast to low-grade astrocytomas, the angiogenesis score of low-grade oligodendrogliomas (counting the number of microvessels in tumor tissue) adds little information to help predict tumor behavior.

Expression of vascular permeability factor in glioblastoma specimens: correlation with tumor vascular endothelial surface and peritumoral edema

Keeping in mind that the expression of vascular permeability factor (VPF) in astrocytic tumors has been related to tumor angiogenesis and peritumoral edema (PE), the aim of this study is to investigate the correlation between degree of VPF expression by tumor cells, and degree of PE and vascular endothelial surface (VES) in glioblastoma. Tumor tissue and neuroimaging data were studied in a series of 38 patients with glioblastoma. For each tumor, immunohistochemical and morphometric studies were performed in order to obtain a score of VPF expression, and a VES score, expressed as the CD-34 immunostained endothelial surface per each 1000 tumor cells. These parameters were related to the degree of PE. The results show that in glioblastomas there exist a clear correlation between the tumor-cell expression of VPF and VES, but we failed to obtain a significant correlation between degree of PE and degree of VES, or between degree of VPF expression and degree of PE. Our present results suggest that in glioblastomas, tumor angiogenesis is clearly related to the expression of VPF by tumor cells, but factors other than intratumoralpresence of VPF may contribute to the development of PE.

Grafting of neural tissue in chronically injured spinal cord: influence of the donor tissue on regenerative activity

BACKGROUND

To determine the influence of different nervous tissue grafts on the regenerative activity of chronically injured spinal cord, an experimental study examining the expression of the proliferating cell nuclear antigen (PCNA) in chronically injured spinal cord subjected to neural grafting was performed.

METHODS

Three months after induced spinal cord injury, paraplegic Wistar rats were subjected to grafting of neural tissue. Grafts consisted of fetal brain cortex, fetal spinal cord, crushed adult peripheral nerve tissue, or fetal brain cortex combined with crushed adult peripheral nerve tissue. Four months later, the spinal cord was removed and the grafted zone was studied by means of immunohistochemical demonstration of PCNA.

RESULTS

Different patterns of PCNA expression were recorded in the different experimental groups. PCNA-immunostained cells in injured spinal cord tissue, mainly ependymal cells and astrocytes, increased when co-transplantation of fetal brain cortex and crushed adult peripheral nerve tissue was used, in comparison to other neural donor tissues. In the grafted tissue, proliferative activity was greater when fetal brain cortex, alone or with peripheral nerve, was used, in comparison to the use of fetal spinal cord or adult peripheral nerve tissue. Nevertheless, the number of PCNA-positive cells does not seem to be influenced by the presence of peripheral nerve tissue in the donor tissue.

CONCLUSIONS

Our present findings suggest the effectiveness of co-transplantation of peripheral nerve tissue and fetal brain tissue in attempts at spinal cord reconstruction after injury.

Cerebral angiofibroma: case report

OBJECTIVE AND IMPORTANCE

Intracranial fibromatous tumors are very rare lesions, with few reported cases.

CLINICAL PRESENTATION

We report the case of a 34-year-old male patient who experienced seizures resulting from a cystic lesion in the left occipital region, which remained unchanged for 11 years. After the seizures increased in number, magnetic resonance imaging revealed a large cyst with a tumor nodule.

INTERVENTION

A left occipital craniotomy was performed, and the tumor was removed. Pathological studies, including immunohistochemical and ultrastructural analyses, indicated that this neoplasm was composed of fibrous and angiomatous components, and a diagnosis of cerebral angiofibroma was established.

CONCLUSION

Cerebral and meningeal fibromas are rare neoplasms that differ from solitary fibrous tumors and fibrous meningiomas. When a number of prominent blood vessels are present in a cerebral or meningeal fibroma, a diagnosis of angiofibroma can be considered. It is possible that some nodular brain tumors that were previously described as meningioangiomatosis could be reclassified as cerebral or meningeal angiofibromas.

Expression of vascular permeability factor in craniopharyngioma

OBJECT

The expression of vascular endothelial growth/permeability factor (VEG/PF) has recently been correlated with the presence of tumor-associated cysts in some intracranial tumors. The purpose of this study was to evaluate a possible relationship between the presence of VEG/PF and the formation of cysts in craniopharyngiomas.

METHODS

The expression of VEG/PF was studied in histological specimens from a series of 12 craniopharyngiomas. In this series, the tumors were classified as presenting a mainly solid pattern with small macroscopic cysts (four patients) or a mainly cystic pattern (eight patients). The mainly solid tumors containing small macroscopic cysts showed little or no VEG/PF positivity, which was mainly present in tumor cells surrounding cysts. Nevertheless, mainly cystic craniopharyngiomas showed a moderate or high degree of VEG/PF positivity in tumor cells.

CONCLUSIONS

These findings indicate that the predominance of a cystic or solid macroscopic appearance of craniopharyngiomas may be influenced by the degree of VEG/PF expression within the tumor cells.

Molecular characterization of the 5' control region and of two lethal alleles affecting the hsp60 gene in Drosophila melanogaster

The chaperonins are evolutionarily conserved essential cellular proteins that help folding newly synthesized or translocated proteins, spending ATP. We present here the molecular analysis of the hsp60 gene promoter region and of two Drosophila hsp60 ethyl methane sulfonate embryonic lethal alleles that have an identical phenotype. No heat shock element sequences were found in the 5' region, supporting previous data (Kozlova, T. et al., 1997) which suggests that mitochondrial Drosophila melanogaster HSP60.1 is not heat inducible. By sequencing the lethal allele's entire open reading frame (ORF), we found a C-T transition in the hsp60F409 allele that produces a serine to leucine change, apparently distorting the protein equatorial domain structure. No changes were found in the hsp60G93 ORF. However, an analysis of the heterogeneous nuclear RNA levels showed a reduction of the hsp60 transcript in hsp60G93 flies as compared to the wild-type. These data suggest that although the defects in the hsp60 gene produced by these alleles are at different levels, both behave as null mutations.

Differential expression of mitochondrial genes between queens and workers during caste determination in the honeybee Apis mellifera

The nourishment received by female honeybee larvae determines their differentiation into queens or workers. In this study, we report the first molecular analysis of differences that occur between queens and workers during the caste-determination process. RNA-differential display experiments identified a clone that encodes for a gene that is homologous to the nuclear-encoded mitochondrial translation initiation factor (AmIF-2mt). Semi-quantitative analysis by reverse transcriptase/polymerase chain reaction (RT-PCR) throughout honeybee development detected a higher level of expression of this gene in queen larvae than in worker larvae. Analysis of two other genes encoding mitochondrial proteins, cytochrome oxidase subunit 1 (COX-1; mitochondrial-encoded) and cytochrome c (cyt c; nuclear-encoded) also showed differential expression of these two genes between queens and workers. In particular, the cyt c transcript is more abundant in queen larvae and throughout the metamorphosis of the queen. These results indicate that the higher respiratory rate previously documented in queen larvae is accomplished through a higher level of expression of both nuclear- and mitochondrial-encoded genes for mitochondrial proteins.

Vascular endothelial growth/permeability factor in spinal cord injury

OBJECT

Predicated on the hypothesis that this cytokine can contribute to the development of vascular hyperpermeability, leading to tissue edema after trauma, the purpose of this study was to determine the presence in tissue of vascular endothelial growth/permeability factor (VEG/PF) after experimental spinal cord injury.

METHODS

The presence of VEG/PF was studied at 8 hours and 2, 8, and 14 days after a traumatic injury in adult Wistar rats. Studies were conducted in which a monoclonal antibody to the VEG/PF was used. Strong VEG/PF immunoreactivity was detected in the walls of pial and intramedullary vessels and in reactive astrocytes 8 hours posttrauma and was unchanged on Days 2 and 8. By Day 14, immunoreactivity decreased, and most of the arterioles from the pia and gray matter showed no mural VEG/PF.

CONCLUSIONS

The authors' present findings suggest a role for this cytokine in the development of tissue edema after spinal cord trauma and point to the possible usefulness of a therapeutic approach to spinal cord injury based on blocking the cell expression of VEG/PF or its physiological effects.

The Drosophila melanogaster homologue of the Xeroderma pigmentosum D gene product is located in euchromatic regions and has a dynamic response to UV light-induced lesions in polytene chromosomes

The XPD/ERCC2/Rad3 gene is required for excision repair of UV-damaged DNA and is an important component of nucleotide excision repair. Mutations in the XPD gene generate the cancer-prone syndrome, xeroderma pigmentosum, Cockayne's syndrome, and trichothiodystrophy. XPD has a 5'- to 3'-helicase activity and is a component of the TFIIH transcription factor, which is essential for RNA polymerase II elongation. We present here the characterization of the Drosophila melanogaster XPD gene (DmXPD). DmXPD encodes a product that is highly related to its human homologue. The DmXPD protein is ubiquitous during development. In embryos at the syncytial blastoderm stage, DmXPD is cytoplasmic. At the onset of transcription in somatic cells and during gastrulation in germ cells, DmXPD moves to the nuclei. Distribution analysis in polytene chromosomes shows that DmXPD is highly concentrated in the interbands, especially in the highly transcribed regions known as puffs. UV-light irradiation of third-instar larvae induces an increase in the signal intensity and in the number of sites where the DmXPD protein is located in polytene chromosomes, indicating that the DmXPD protein is recruited intensively in the chromosomes as a response to DNA damage. This is the first time that the response to DNA damage by UV-light irradiation can be visualized directly on the chromosomes using one of the TFIIH components.

Vascular permeability factor expression in cerebellar hemangioblastomas: correlation with tumor-associated cysts

The presence of vascular endothelial growth/permeability factor (VEG/PF) has been studied in histological specimens from a series of 16 cerebellar hemangioblastomas. In this series, the tumors were classified as presenting a macroscopic solid pattern (4 cases), a mainly solid pattern with macroscopic cysts (4 cases) or a mainly cystic pattern (8 cases). Solid tumors showed a low degree (75% of cases) or moderate degree (25% of cases) of VEG/PF positivity. The mainly solid tumors containing macroscopic cysts showed a moderate degree (50% of cases) or high degree (50% of cases) of VEG/PF positivity. Nevertheless, mainly cystic hemangioblastomas showed a high degree (87.5% of cases) or moderate degree (12.5% of cases) of VEG/PF positivity. These findings suggest that the predominance of a cystic or solid macroscopic appearance of cerebellar hemangioblastomas may be influenced by the degree of VEG/PF expression within the tumor tissue.

Molecular analysis and chromosome mapping of the H2A, H3 and H4 histone genes from the malaria vector Anopheles gambiae

In this article we report the cloning and analysis of PCR generated fragments that encode H2A, H3 and H4 histone genes from the malaria vector An. gambiae. Sequence analysis indicated that some conservative changes are present in the An. gambiae H2A and H4 genes as compared with histone genes from other organisms. Divisional mapping showed that these genes map in division 20 on the left arm of the second chromosome. Southern blot experiments and the molecular characterization of the genomic fragment containing the H2A, H2B, H3 and H4 genes showed that they are organized in a cluster with an orientation different from the one found in other dipterans.