The blood-tendon barrier: identification and characterisation of a novel tissue barrier in tendon blood vessels

Tissue barriers function as "gate keepers" between different compartments (usually blood and tissue) and are formed by specialised membrane-associated proteins, localising to the apicolateral plasma membrane domain of epithelial and endothelial cells. By sealing the paracellular space, the free diffusion of solutes and molecules across epithelia and endothelia is impeded. Thereby, tissue barriers contribute to the establishment and maintenance of a distinct internal and external environment, which is crucial during organ development and allows maintenance of an organ-specific homeostatic milieu. So far, various epithelial and endothelial tissue barriers have been described, including the blood-brain barrier, the blood-retina barrier, the blood-testis barrier, the blood-placenta barrier, and the cerebrospinal fluid (CSF)-brain barrier, which are vital for physiological function and any disturbance of these barriers can result in severe organ damage or even death. Here, we describe the identification of a novel barrier, located in the vascular bed of tendons, which we term the blood-tendon barrier (BTB). By using immunohistochemistry, transmission electron microscopy, and tracer studies we demonstrate the presence of a functional endothelial barrier within tendons restricting the passage of large blood-borne molecules into the surrounding tendon tissue. We further provide in vitro evidence that the BTB potentially contributes to the creation of a distinct internal tissue environment impacting upon the proliferation and differentiation of tendon-resident cells, effects which might be fundamental for the onset of tendon pathologies.

Local recurrence of deep-seated, high-grade, soft tissue sarcoma: 459 patients from the Scandinavian Sarcoma Group Register

This study was based on 459 adult patients with deep, high-grade, soft tissue sarcoma of extremities or trunk wall reported to the Scandinavian Sarcoma Group Register (1986-1993). All patients had their definitive surgery for primary tumor at a sarcoma center. The median follow-up was 7.5 (3-12) years. 204 patients are still alive. 68 patients had amputations and 391 underwent limb-sparing surgery. Among 183 patients with intralesional or marginal margins after limb-sparing surgery, 65% had postoperative radiotherapy and 9% of the 198 patients with wide margins. The local recurrence rate after limb-sparing surgery was 26%. The rate with an intralesional or marginal margin was 39% without postoperative radiotherapy versus 24% when radiotherapy was given. It was 25% after a wide margin, and no recurrences were noted among the 10 patients with a compartmental surgical margin. Among patients with a wide margin, a subset fulfilling criteria for a myectomy was defined. The local recurrence rate was 26% among these 62 and there was no advantage of myectomy over other wide margins. More radical surgical margins would improve the local recurrence rate, but this can hardly be achieved in center-operated patients without increasing the amputation rate. Instead, increased use of radiotherapy in all patients with inadequate margins, and to a larger extent in those with wide margins will improve local control.

Perivascular cells of the supraspinatus tendon express both tendon- and stem cell-related markers

Tendons and ligaments are often affected by mechanical injuries or chronic impairment but other than muscle or bone they possess a low healing capacity. So far, little is known about regeneration of tendons and the role of tendon precursor cells in that process. We hypothesize that perivascular cells of tendon capillaries are progenitors for functional tendon cells and are characterized by expression of marker genes and proteins typical for mesenchymal stem cells and functional tendon cells. Immunohistochemical characterization of biopsies derived from intact human supraspinatus tendons was performed. From these biopsies perivascular cells were isolated, cultured, and characterized using RT-PCR and Western blotting. We have shown for the first time that perivascular cells within tendon tissue express both tendon- and stem/precursor cell-like characteristics. These findings were confirmed by results from in vitro studies focusing on cultured perivascular cells isolated from human supraspinatus tendon biopsies. The results suggest that the perivascular niche may be considered a source for tendon precursor cells. This study provides further information about the molecular nature and localization of tendon precursor cells, which is the basis for developing novel strategies towards tendon healing and facilitated regeneration.

MyoD and Myogenin expression during myogenic phases in brown trout: a precocious onset of mosaic hyperplasia is a prerequisite for fast somatic growth

Muscle cell recruitment (hyperplasia) during myogenesis in the vertebrate embryo is known to occur in three consecutive phases. In teleost fish (including zebrafish), however, information on myogenic precursor cell activation is largely fragmentary, and comprehensive characterization of the myogenic phases has only been fully undertaken in a single slow-growing cyprinid species by examination of MEF2D expression. Here, we use molecular techniques to provide a comprehensive characterization of MyoD and Myogenin expression during myogenic cell activation in embryos and larvae of brown trout, a fast-growing salmonid with exceptionally large embryos. Results confirm the three-phase pattern, but also demonstrate that the second and third phases begin simultaneously and progress vigorously, which is different from the previously described consecutive activation of these phases. Furthermore, we suggest that Pax7 is expressed in myogenic progenitor cells that account for second- and third-phase myogenesis. These findings are discussed in relation to teleost myotome development and to teleost growth strategies.

In Search of the Astrocytic Factor(s) Modulating Blood–Brain Barrier Functions in Brain Capillary Endothelial Cells In Vitro

(1) The blood-brain barrier (BBB) is formed by brain capillary endothelial cells (ECs). There are various cell types, in particular astrocytes, but also pericytes and neurons, located in close vicinity to the capillary ECs which may influence formation and function of the BBB. Based on this consideration, this paper discusses various aspects of the influence of the surrounding cells on brain capillary ECs with special focus on the role of astrocytes. (2) Based on the morphology of the BBB, important aspects of brain EC functions are summarized, such as transport functions and maintenance of low paracellular permeability. Moreover, various facets are discussed with respect to the influence of astrocytes, pericytes, microglia, and neurons on the BBB. Data on the role of glial cells in the ontogenesis of the BBB are presented subsequently. The knowledge on this subject is far from being complete, however, these data imply that the neural/neuronal environment rather than glial cells may be of importance in the maturation of the barrier. (3) The role of glial cells in the induction and maintenance of the BBB is discussed under physiological as well as pathological conditions. Although the literature presents manifold evidence for a great variety of effects induced by astroglia, there are also many controversies, which may result from different cellular models and experimental conditions used in the respective studies. Numerous factors secreted by astrocytes have been shown to induce a BBB phenotype. On the molecular level, increased expression of barrier-relevant proteins (e.g., tight junction proteins) is documented in the presence of astrocyte-derived factors, and many studies demonstrate the improvement of physiological parameters, such as increased transendothelial resistance and decreased paracellular permeability, in different in vitro models of the BBB. Moreover, one has to take into account that the interaction of brain ECs and astrocytes is bi-directional, and that the other cell types surrounding the brain microvasculature also contribute to BBB function or dysfunction, respectively. (4) In conclusion, it is expected that the present and future research focused on molecular mechanisms and signaling pathways will produce new and exciting insights into the complex network of BBB regulation: the cornerstone is laid.

Oxidative stress in cultured cerebral endothelial cells induces chromosomal aberrations, micronuclei, and apoptosis

There is evidence accumulating that brain microvasculature is involved critically in oxidative stress-mediated brain damage. Cultured cerebral microvascular endothelial cells were used to demonstrate the cytotoxic and genotoxic effects elicited by hypoxia/reoxygenation and DMNQ treatment in vitro. In addition, the effect of glucose deprivation during oxidative insult was assessed. The parameters determined were: 1) chromosomal aberrations; 2) induction of micronuclei; and 3) apoptosis. Our results indicate that both the exposure of the cerebral endothelial cells to 24 hr of hypoxia followed by 4 hr of reoxygenation, and treatment with the redox cycling quinone DMNQ, increased markedly the occurrence of chromosomal aberrations and micronuclei. It was found that expression of p53 was induced by oxidative stress, particularly when glucose had been omitted from the culture medium. Aglycemic culture conditions in general exacerbated the cytotoxic effects of oxidative insults, as evidenced by the increase in apoptotic cells and the decrease in the mitotic index. Interestingly, neither an elevation of cell lysis nor an increase in necrosis has been observed during our experiments. In summary, our data indicate that oxidative stress exerts considerable genotoxic and cytotoxic effects on cerebral endothelial cells, which might contribute to the progression of tissue damage in the central nervous system.

The kaleidoscopic mind of Peter Mark Roget

PETER MARK ROGET died on 12 September 1869, Nevertheless, he is more widely known today than he ever was in his heyday. His name has endured a full century, and may indeed endure for ever, primarily because of the great popularity, extraordinary sale, and unforgettable title of his Thesaurus of English Words and Phrases. This astonishing collection of interchangeable parts of speech, ‘classified and arranged … so as to facilitate the expression of ideas and assist in literary composition’, was first published in 1852, long after Roget had retired from medical practice and shortly after he had given up his post as secretary of the Royal Society. He was already 73 years old, but since he could not slacken his habitual pace, he continued to work unceasingly on revision after revision until there were twenty‐eight revisions when he died seventeen years later. After his death, his son, John Lewis Roget, edited the Thesaurus until 1908; a grandson, Samuel Romilly Roget, then took over the editorship and retained control over the legacy until 1936.

Identification and localization of M-CoREST (1A13), a mouse homologue of the human transcriptional co-repressor CoREST, in the developing mouse CNS

By means of subtractive and differential hybridization techniques we have identified a novel murine gene (1A13) the expression of which is developmentally regulated in the mouse brain. Comparison of the nucleotide and predicted protein sequence revealed closest relationship of 1A13 to human CoREST, a transcriptional co-repressor required for regulation of neural-specific gene expression. Thus, we will refer to 1A13 as M-CoREST. As shown by in situ hybridization and Northern blotting, expression of M-CoREST mRNA is abundant in neural tissue at early embryonic stages but declines significantly towards birth, coincident with the progression of CNS maturation.

Surgical treatment for skeletal breast cancer metastases: a population-based study of 641 patients

BACKGROUND

The objective of this article was to assess the occurrence of symptomatic bone metastases in a defined population of patients with breast carcinoma and to characterize the clinical outcome with reference to surgical treatment for pathologic fracture or neurologic deficit.

METHODS

The authors identified all patients in the Stockholm Breast Cancer Database (population base 1.8 million) with a diagnosis of bone metastases during 1989--1994. These cases were linked with the Stockholm County Council Hospital Discharge Diagnosis Registry that includes information on in-patient care and discharge diagnoses. This enabled us to identify patients who had undergone surgical treatment for their bony metastases at any of the six departments of orthopedics in the region, or who had been treated at the one department of neurosurgery.

RESULTS

Six hundred forty-one patients with breast carcinoma presented with symptomatic skeletal metastasis during 1989--1994, and 107 (17%) were operated on. Metastases were located in long bones (77), spine (14), and pelvis (6). The median survival postoperatively was 6 months. The total reoperation rate was 0.12. Hip screws and glide-screw plates were associated more often with failure as was location in the distal femur. Pain decreased postoperatively in 77% of the patients, and function improved in 65%.

CONCLUSIONS

One in 10 patients with breast carcinoma developed symptomatic bone metastases, and one-fifth of these patients required surgery for pathologic fracture or neurologic deficit. There was a high failure rate in those hospitals in which few patients were operated on.

Monitoring referral and treatment in soft tissue sarcoma: study based on 1,851 patients from the Scandinavian Sarcoma Group Register

This report is based on 1.851 adult patients with soft tissue sarcoma (STS) of the extremities or trunk wall diagnosed between 1986 and 1997 and reported from all tertiary referral centers in Norway and Sweden. The median age at diagnosis was 65 years and the male-to-female ratio was 1.1:1. One third of the tumors were subcutaneous, one third deep, intramuscular and one third deep, extramuscular. The median size was 7 (1-35) cm and 75% were high grade (III-IV). Metastases at presentation were diagnosed in 8% of the patients. Two thirds of STS patients were referred before surgery and the referral practices have improved during the study. The preoperative morphologic diagnosis was made with fine-needle aspiration cytology in 81%, core-needle biopsy in 9% and incisional biopsy in 10%. The frequency of amputations has decreased from 15% in 198688 to 9% in 1995-1997. A wide surgical margin was achieved in 77% of subcutaneous and 60% of deep-seated lesions. Overall, 24% of operated STS patients had adjuvant radiotherapy. The use of such therapy at sarcoma centers increased from 20% 1986-88 to 30% in 1995-97. Follow-up has been reported in 96% of the patients. The cumulative local recurrence rate was 0.20 at 5 years and 0.24 at 10 years. The 5-year metastasis-free survival rate was 0.70.

Diagnosis of skeletal lymphoma and myeloma by radiology and fine needle aspiration cytology

Diagnosis of skeletal lymphoma and myeloma by radiology and fine needle aspiration cytology From 1986 to 1998, all patients referred to Karolinska Hospital because of a skeletal destruction of unknown origin routinely underwent radiographic examination and fine needle aspiration cytology (FNAC). Among these, there were 83 patients with solitary lesions of the bone diagnosed and treated for myeloma (plasmacytoma) or non-Hodgkin's lymphoma. Review of the series showed that myeloma could not be distinguished radiographically from lymphoma. Nor could low and high grade lymphoma lesions be discriminated by radiographic appearance. The diagnostic utility of plain radiography in the two conditions seems to be confined to the mere detection of a destructive bone lesion and visual guidance for FNAC. The latter aspect, however, is crucial for the application of FNAC to bone lesions. Review of the cytologic specimens obtained by FNAC showed that they allowed a conclusive diagnosis in all 40 myeloma cases and in 41 of 43 lymphoma cases. In 32 of the 40 myeloma cases, the FNAC material could be used for immunocytochemistry, which disclosed kappa or lambda light chain restriction, corroborating the cytomorphological diagnosis. Thirty-eight lymphomas were characterized immunologically and in 35, a light chain restriction could be demonstrated. Our results show that the use of FNAC in the diagnosis of primary myeloma and lymphoma of bone obviates the need for other diagnostic modalities, including open biopsy. A combined approach based on radiology and FNAC, performed as an out-patient procedure, offers rapid and accurate diagnosis of myeloma and lymphoma among patients with radiographically unclassified destructive bone lesions.

Immunolocalization of occludin and claudin-1 to tight junctions in intact CNS vessels of mammalian retina

The distributions of occludin and claudin-1, two tight junction-associated integral membrane proteins were investigated by immunohistochemical analysis of whole-mount preparations of the blood vessels in the myelinated streak of the rabbit retina. Light microscopy revealed that occludin and claudin-1 immunoreactivities were abundant along the interface of adjacent endothelial cells of all blood vessels. Electron microscopy revealed that both proteins were distributed in a regular pattern (at regular intervals of approximately 80 nm) along the length of tight junctions, probably in the regions of tight junction strands. No other structures or cell types expressed either of these two proteins in the myelinated streak. Whereas occludin immunoreactivity was concentrated only at the tight junction interface, claudin-1 immunoreactivity also extended into the cytoplasm of the endothelial cells, suggesting a different structural role for claudin-1 than for occludin at tight junctions. Retinal pigment epithelial cells expressed occludin around their entire circumference, consistent with the function of these cells as a barrier separating the retina from the leaky vessels of the choroid. Also consistent with the association of occludin expression with vessels that exhibit functional tight junctions, this protein was expressed at only a low level in, and showed an irregular distribution along, the vessels of the choroid, a vascular bed that lacks blood-barrier properties. Further, the distribution of occludin was examined during formation and remodelling of the rat retinal vasculature. Occludin expression was evident at the leading edge of vessel formation and was found on all vessels in both the inner and outer vascular plexus. Numerous vascular segments at the early stage of vascular formation and regression lost occludin expression. The biological significance of this transient loss of occludin expression in terms of barrier function remains to be elucidated.

Pre-operative radiotherapy in soft tissue tumors. Assessment of response by static post-contrast MR imaging compared to histopathology

PURPOSE

To evaluate if static post-contrast MR imaging was adequate to assess tumor viability after pre-operative radiotherapy in soft tissue sarcoma.

MATERIAL AND METHODS

Post-contrast MR imaging of 36 soft tissue sarcomas performed 0-54 days (median 13 days) after pre-operative radiotherapy, were retrospectively reviewed and compared to post-operative histopathology reports. The contrast enhancement of the tumor was visually graded as minor, moderate or extensive. From the post-operative histopathology reports, three types of tumor response to radiotherapy were defined: Poor, intermediate or good. The size of the tumors before and after radiation was compared.

RESULTS

Even if most viable tumors enhanced more than non-viable tumors, there was major overlapping and significant contrast enhancement could be seen in tumors where histopathological examination revealed no viable tumor tissue. Based on histopathology, there were 12 good responders; 8 of these showed minor, 3 moderate and 1 extensive contrast enhancement on MR imaging. Sixteen tumors had an intermediate response; 3 showed minor, 8 moderate and 5 extensive enhancement. Eight tumors had poor response; none showed minor enhancement, 3 moderate and 5 extensive enhancement. Both increase and decrease in tumor size was seen in lesions with a good therapy response.

CONCLUSION

Static post-contrast MR imaging cannot reliably assess tumor viability after pre-operative radiotherapy in soft tissue sarcoma. In tumors with no viable tumor tissue, moderate and extensive contrast enhancement can be seen.

Use of genetically modified glial cells overexpressing laminin alpha1-chain peptides in neurite outgrowth studies

1. C6 glioma cells were transfected with two constructs carrying C-terminal laminin alpha1-chain sequences of 117 and 114 bp length, respectively. These sequences are specifically known to code for peptides which have neurite-promoting activity. 2. The stable expression and secretion of the two peptides was detected by Northern and Western blot analysis. 3. Primary neuronal cultures derived from embryonic mouse forebrain were cocultured with these transfected cells and exhibited a substantial increase in neurite outgrowth and in survival time. Conditioned media from the transfected cells generated similar effects. 4. Organotypic cultures from embryonic mouse brain were used as a second system as being closer to the in vivo situation. Again, coculture of brain slices with transfected cells or treatment with laminin peptide-containing media increased neuronal outgrowth.

Consequences of local recurrence of soft tissue sarcoma: 205 patients from the Scandinavian Sarcoma Group Register

From the Scandinavian Sarcoma Group Register, information on 1,224 surgically-treated patients with soft tissue sarcoma (STS) of the extremity or trunk wall, diagnosed between 1987 and 1995, was collected. 205 patients, one third of whom were referred to a center with a local recurrence, had a total of 284 local recurrences. This analysis describes the treatment for these local recurrences, complications and risk of further recurrences. 169 patients were surgically treated for their first local recurrence. An intralesional or marginal margin was achieved in 110 of these patients, 59 of whom were also given radiotherapy. 54 of the 169 patients had a second local recurrence. The second local recurrence rate was 0.50 if the first local recurrence had been treated with only surgery with a marginal margin, compared to 0.28 if treated with surgery with a marginal margin and radiotherapy or with a wide margin (p = 0.0008). In extremity STS, the crude amputation rate for local recurrences was 0.22 (31 of 142)-i.e., higher than for primary tumors 0.09 (96 of 1065) (p < 0.0001). A high local recurrence rate after treatment outside of sarcoma centers has earlier been shown. We conclude that the consequences of local recurrence in terms of morbidity and costs justifies referral of STS patients for multidisciplinary evaluation and multimodality treatment.

Growth factor-induced morphological, physiological and molecular characteristics in cerebral endothelial cells

The capacity of vascular endothelial cells to modulate their phenotype in response to changes in environmental conditions is one of the most important characteristics of this cell type. Since different growth factors may play an important signalling role in this adaptive process we have investigated the effect of endothelial cell growth factor (ECGF) on morphological, physiological and molecular characteristics of cerebral endothelial cells (CECs). CECs grown in the presence of ECGF and its cofactor heparin exhibit an epithelial-like morphology (type I CECs). Upon removal of growth factors, CECs develop an elongated spindle-like shape (type II CECs) which is accompanied by the reorganization of actin filaments and the induction of alpha-actin expression. Since one of the most important functions of CECs is the creation of a selective diffusion barrier between the blood and the central nervous system (CNS), we have studied the expression of junction-related proteins in both cell types. We have found that removal of growth factors from endothelial cultures leads to the downregulation of cadherin and occludin protein levels. The loss of junctional proteins was accompanied by a significant increase in the migratory activity and an altered protease activity profile of the cells. TGF-beta1 suppressed endothelial migration in all experiments. Our data provide evidence to suggest that particular endothelial functions are largely controlled by the presence of growth factors. The differences in adhesiveness and migration may play a role in important physiological and pathological processes of endothelial cells such as vasculogenesis or tumor progression.

Cytological diagnosis of skeletal lesions. Fine-needle aspiration biopsy in 110 tumours

We have previously shown that cytological diagnosis based on fine-needle aspiration biopsy (FNAB) is a safe and efficient method for the discrimination between benign, primary malignant and metastatic bony lesions. We have now studied metastatic lesions to assess the diagnostic accuracy and to ascertain whether FNAB allows identification of the primary lesion. Between 1990 and 1997, 447 patients were referred for diagnosis of skeletal lesions of unknown type. Of these 119 proved to have metastatic disease, either myeloma or lymphoma. Nine were excluded leaving 110 consecutive patients with metastatic carcinoma (80), myeloma (16) or lymphoma (14). FNAB gave a correct diagnosis in 102 of the 110 patients (93%). In eight it was inconclusive. It correctly diagnosed 15 of 16 patients with myeloma, 12 of 14 with lymphoma, and 75 of 80 with metastatic carcinoma. Furthermore, the site and type of malignancy were correctly suggested in two-thirds of patients with metastatic carcinoma. Overall, only seven open biopsies were carried out. We conclude that time-consuming and costly investigations can be reduced by choosing FNAB as the initial diagnostic method for skeletal lesions of unknown origin. The choice of radiological examinations, laboratory tests and surgical biopsies can be determined by using FNAB.

Surgical margins, local recurrence and metastasis in soft tissue sarcomas: 559 surgically-treated patients from the Scandinavian Sarcoma Group Register

The prognostic importance of surgical margins on local recurrence rates and metastasis-free survival (MFS) was studied in 559 patients with soft tissue sarcoma of the extremities and trunk wall. The patients were all surgically treated, but received no adjuvant treatment. The median follow-up for the survivors was 7.4 (range: 0.1 - 12.5) years. Independent prognostic factors for MFS were analysed by Cox models. The overall 5-year MFS was 0.72 (95% confidence intervals (CI) 0.68 - 0.76). High histopathological malignancy grade (relative risk (RR) 3.0; 95% CI 1.5 - 6.3) and an inadequate surgical margin (RR 2.9; 95% CI 1.8 - 4.6) were independent risk factors for local recurrence. High histopathological malignancy grade and large tumour size (> 7 cm) were the most important risk factors for metastasis. Local recurrence was associated with an increased risk of metastasis (RR 4. 4; 95% CI 2.9-6.8), but an inadequate surgical margin was not a risk factor for metastasis (RR 1.1; 95% CI 0.8-1.7). This study confirms that, as regards metastasis, tumour-related risk factors (malignancy grade and tumour size) are more important risk factors than treatment-related factors. Local recurrence was associated with an increased metastasis rate, whereas inadequate surgical margin was a risk factor for local recurrence but not for metastasis. Hence, the proposed causal association between local recurrence and metastasis is doubtful, and if it exists is a weak association.

Neural induction of the blood-brain barrier: still an enigma

1. The study of the blood-brain barrier and its various realms offers a myriad of opportunities for scientific exploration. This review focuses on two of these areas in particular: the induction of the blood-brain barrier and the molecular mechanisms underlying this developmental process. 2. The creation of the blood-brain barrier is considered a specific step in the differentiation of cerebral capillary endothelial cells, resulting in a number of biochemical and functional alterations. Although the specific endothelial properties which maintain the homeostasis in the central nervous system necessary for neuronal function have been well described, the inductive mechanisms which trigger blood-brain barrier establishment in capillary endothelial cells are unknown. 3. The timetable of blood-brain barrier formation is still a matter of debate, caused largely by the use of varying experimental systems and by the general difficulty of quantitatively measuring the degree of blood-brain barrier "tightness." However, there is a general consensus that a gradual formation of the blood-brain barrier starts shortly after intraneural neovascularization and that the neural microenvironment (neurons and/or astrocytes) plays a key role in inducing blood-brain barrier function in capillary endothelial cells. This view stems from numerous in vitro experiments using mostly cocultures of capillary endothelial cells and astrocytes and assays for easily measurable blood-brain barrier markers. In vivo, there are great difficulties in proving the inductive influence of the neuronal environment. Also dealt with in this article are brain tumors, the least understood in vivo systems, and the induction or noninduction of barrier function in the newly established tumor vascularization. 4. Finally, this review tries to elucidate the question concerning the nature of the inductive signal eliciting blood-brain barrier formation in the cerebral microvasculature.

Zinc protects against apoptosis of endothelial cells induced by linoleic acid and tumor necrosis factor alpha

BACKGROUND

Zinc requirements of the vascular endothelium may be increased in inflammatory conditions, ie, atherosclerosis, in which apoptotic cell death is prevalent.

OBJECTIVE

We hypothesized that zinc deficiency may potentiate disruption of endothelial cell integrity mediated by fatty acids and inflammatory cytokines by enhancing pathways that lead to apoptosis and up-regulation of caspase genes.

DESIGN

Endothelial cells were maintained in low-serum medium or grown in culture media containing selected chelators, ie, diethylenetriaminepentaacetate or N,N,N', N'-tetrakis(2-pyridylmethyl)-ethylenediamine (TPEN), with or without zinc supplementation. Subsequently, cells were treated with linoleic acid, tumor necrosis factor alpha (TNF-alpha), or both. We studied the effect of zinc deficiency and supplementation on the induction of apoptosis by measuring caspase-3 activity, cell binding of annexin V, and DNA fragmentation.

RESULTS

Our results indicated that linoleic acid and TNF-alpha independently, but more markedly in concert, up-regulated caspase-3 activity and induced annexin V binding and DNA fragmentation. Zinc deficiency, especially when induced by TPEN, dramatically increased apoptotic cell death induced by cytokines and lipids compared with control cultures. Supplementation of low-serum- or chelator-treated endothelial cells with physiologic amounts of zinc caused a marked attenuation of apoptosis induced by linoleic acid and TNF-alpha. Morphologic changes of cells observed during zinc deficiency were prevented by zinc supplementation. Media supplementation with other divalent cations (eg, calcium and magnesium) did not mimic the protective role of zinc against apoptosis.

CONCLUSIONS

Our data indicate that zinc is vital to vascular endothelial cell integrity, possibly by regulating signaling events to inhibit apoptotic cell death.

Clinical course in synovial sarcoma: a Scandinavian sarcoma group study of 104 patients

We analyzed treatment and outcome in 104 Scandinavian patients with synovial sarcoma in the extremities or trunk wall, diagnosed between 1986 and 1994. Only surgically treated patients without metastases at diagnosis were included. Median follow-up of survivors was 6 (3-11) years. 34 patients developed metastases. The overall 5- and 7-year survival rates were 0.76 (95% CI 0.66-0.83) and 0.69 (0.58-0.78), respectively. Large tumor size and amputation were significantly associated with impaired metastasis-free survival. Patients with local recurrence had a higher risk of metastases following the local event. Local excision with inadequate margin was associated with a higher risk of local recurrence.

110 subfascial lipomatous tumors. MR and CT findings versus histopathological diagnosis and cytogenetic analysis

PURPOSE

To evaluate whether liposarcoma, atypical lipomatous tumors and lipoma can be differentiated radiologically.

MATERIAL AND METHODS

We have retrospectively analyzed CT and/or MR images of 110 subfascial lipomatous lesions. The amount of fat within the tumors was visually graded from the images as: none, 1-75%, 75-95% or 95-100%. The structure of non-fatty tumor components was compared. The images were compared to histopathology and in 37 cases to cytogenetic findings.

RESULTS

Only 4 of 20 liposarcomas contained fat. All 4 lesions, histopathologically diagnosed as atypical lipomatous tumors, contained fat but less than 75% of tumor volume. All lesions with more fat than 75% of tumor volume were histologically diagnosed as lipomas. However, one-third of the karyotyped lipomas had ring chromosomes which are considered typical for atypical lipomatous tumors.

CONCLUSION

When a tumor is composed more or less solely of fat, the diagnosis of a lipoma or atypical lipomatous tumor with a phenotype simulating a lipoma can be assumed. When the fat content is less than 75% of the tumor volume or non-fatty nodules are found, biopsies from different tumor components have to be performed to exclude malignancy. When no fat is found, imaging does not help in differentiating lipoma or liposarcoma from other soft tissue tumors.

Clinical significance of genetic imbalances revealed by comparative genomic hybridization in chondrosarcomas

DNA copy number changes were studied by comparative genomic hybridization (CGH) in 50 chondrosarcoma samples from 45 patients. Mean number of genetic aberrations in primary tumors was 4.8 +/- 1.8. The most frequently gained regions were 20q12-qter (37%), 20q (32%), 8q24.1-qter (27%), 20p (24%), and 14q24-qter (24%). Losses were 5.5 times less frequent than gains and observed mainly at Xcen-q21, 6cen-q22, and 18cen-q11.2 (11% each). Recurrent and metastatic tumors showed a mean of 4.0 +/- 2.2 aberrations per sample. The most frequently gained regions were chromosome 7 (4 cases), 5q14-q32 (4 cases), 6p (3 cases), and 12q (3 cases). Losses of DNA sequences were 3.4 times less frequent than gains. Histological tumor grade was significantly associated with metastasis-free survival (P = .002) and overall survival (P = .003), being the strongest prognostic factor tested. A statistically significant correlation was found between gain at 8q24.1-qter and shorter overall survival (P = .01) but not with local recurrence or metastasis-free survival. Gain at 14q24-qter was associated with a trend to shorter overall survival (P = .05) but neither with an increased risk for local recurrence nor with metastasis-free survival. In a multivariate analysis, only the tumor grade associated with overall survival (P = .02). In a multivariate analysis together with the tumor grade, gain at 8q24.1-qter did not retain its significance (P = .44), indicating that this imbalance is not an independent prognostic factor.

Malignant fibrous histiocytoma of bone: a retrospective EMSOS study of 125 cases. European Musculo-Skeletal Oncology Society

In an effort to learn more about malignant fibrous histiocytoma (MFH) of bone and its prognosis with different treatment approaches, the European Musculo-Skeletal Oncology Society (EMSOS) initiated a retrospective survey among its members. Data requested included patient and treatment variables and outcome. The information on all patients with histologically proven, primary, localized osseous extremity MFH was analyzed if surgical tumor removal was performed and disease status was documented for at least one follow-up date. 125 such patients were evaluable (74 male, 51 female; median age 34 years; tumor site femur 81, tibia 26, humerus 12, other 6). Local treatment was surgery only (110) or surgery plus radiotherapy (15). Chemotherapy was used in 97/125. On last follow-up, 85 patients remained in remission, 33 had developed metastases, 6 a local recurrence, and 1 a combined relapse. With a median follow-up of 3.9 years for patients at risk, actuarial 5-year disease-free survival was 59%. In univariate analyses, younger age and the use of chemotherapy were associated with a more favorable outcome, as was limb-salvage surgery. 23 of 66 tumors with information on response to preoperative chemotherapy responded well (> 90% necrosis). Among these 23, only one relapsed.

Ki-67 is strongly prognostic in synovial sarcoma: analysis based on 86 patients from the Scandinavian Sarcoma group register

In a study based on formalin-fixed paraffin-embedded material from 86 patients with primary synovial sarcoma located in the extremities or on the trunk wall, the prognostic importance of MIB-1 index, p53-expession and tumour size was analysed. Multivariate analysis identified two metastatic risk factors: increasing tumour size and MIB-1 > 9%. The 5-year metastasis-free survival-rate for patients with tumour size < or = 5 cm + MIB-1 < 10% was 0.83 (95% confidence interval (CI) 0.64-0.92) compared to 0.31 (95% CI 0.11-0.53) in cases with tumour size > 5 cm + MIB-1 > or = 10%. Our study shows that metastatic disease in synovial sarcoma is closely related to MIB-1 index. Using our model based on tumour size and MIB-1 index, cases with good and poor prognosis can easily be discriminated. Therefore our model can be used to identify patients who should be considered for adjuvant chemotherapy.

MR imaging of lipoma and liposarcoma

PURPOSE

To evaluate whether lipoma, atypical lipomatous tumors, and liposarcomas can be differentiated by MR images.

MATERIAL AND METHODS

The MR images of 59 lipomatous lesions and liposarcomas were retrospectively reviewed. Apart from size, surgical site, location and margins, the percentage of fat of the tumor volume was assessed as none, 1-75%, 75-95%, or 95-100%.

RESULTS

None of the 18 liposarcomas contained fat that could be recognized by MR imaging. The 3 atypical lipomatous tumors all contained fat but less than 75% of the tumor volume. In 32 of 38 ordinary lipomas, the percentage of fat was 95-100%, and in 4 less than 95% of the tumor volume. Two lipomas did not contain fat that could be recognized by MR imaging.

CONCLUSION

A lesion which predominantly has a fat signal is, in all probability, an ordinary lipoma. Lesions with less fat, but still mostly fatty, may either be lipoma or atypical lipomatous tumor. In this group, the discrimination between these two entities cannot be based upon imaging features. In the absence of a fat signal, liposarcoma or lipoma cannot be differentiated from other soft tissue tumors.

Fine needle aspiration (FNA) cytology in the diagnosis of recurrent soft tissue sarcoma

We have used FNA cytology to diagnose suspected local recurrences of soft tissue sarcoma. Since 1991, a total of 95 FNA cytologies were performed on 86 patients. There were 47 local recurrences, of which 44 were diagnosed correctly by FNA cytology; one biopsy was inconclusive, and two lesions were incorrectly assessed as benign. Thirty-nine patients proved to have benign lesions in the scar area examined cytologically on 50 occasions. None of the specimens was regarded as malignant, but in four cases FNA cytology was inconclusive. Overall, there were 5% inconclusive cytological biopsies, 0% falsely malignant and 5% falsely benign. The inconclusive and false-negative cytological diagnoses had no important clinical consequences. FNA biopsy provides a simple means of diagnosing local recurrence of soft tissue sarcoma.

Cytotoxic and genotoxic effects of 4-hydroxynonenal in cerebral endothelial cells

Oxygen free radicals are produced in the central nervous system (CNS) as a consequence of normal physiological metabolic reactions of neuronal cells, but there is evidence accumulating that they are also implicated in the processes leading to a number of pathological changes in the brain. A general mechanism whereby oxygen free radicals induce tissue damage is lipid peroxidation (LPO), which generates a large variety of water-soluble carbonyl compounds. Due to their high reactivity, we focused our investigations on 4-hydroxyalkenals, in particular on 4-hydroxynonenal (HNE), the major 4-hydroxyalkenal. Two phenotypes of cerebral endothelial cells (cECs) were treated with various concentrations of 4-hydroxynonenal and the cyto- and genotoxic effects studied. The cytogenetic endpoints determined were chromosomal aberrations and the induction of micronuclei. Three hours of incubation with HNE induced significantly elevated levels of chromosomal aberrations at concentrations > or = 1 microM and micronuclei at concentrations > or = 10 microM in both cEC phenotypes, compared to the controls. Cytotoxicity was observed at a concentration of 50 microM HNE and was significantly higher in the elongated and spindle-shaped cEC phenotype (type II) than in the epithelial cEC phenotype (type I). The results indicate that cECs are affected by HNE even at low concentrations with minor differences between the two cEC phenotypes.

Comparison of technetium-99m-MIBI and technetium-99m-tetrofosmin uptake by musculoskeletal sarcomas

Technetium-99m-MIBI was initially developed for heart studies but it can also be used to depict tumors, predict multidrug resistance and evaluate chemotherapy. Recently, 99mTc-tetrofosmin, which exhibits similar physical properties, has been launched for heart studies. Tumor uptake and prediction of multidrug resistance have also been reported regarding the latter tracer. A comparison of these two tracers regarding the detectability of musculoskeletal sarcoma has been made.

METHODS

Twenty patients with musculoskeletal sarcoma of the extremities or pelvis underwent planar examination after the administration of 99mTc-MIBI and 99mTc-tetrofosmin with an interval of 2-7 days. The tumor activity was compared with one ipsilateral and one contralateral background region.

RESULTS

There was a small, but not significant, difference in favor of 99mTc-MIBI with regard to both background regions.

CONCLUSION

Technetium-99m-MIBI and 99mTc-tetrofosmin can both be used to visualize musculoskeletal sarcomas. The choice may depend on which agent is used routinely for myocardial studies in the laboratory.

Use of 99mTc-MIBI scintigraphy in the evaluation of the response of osteosarcoma to chemotherapy

The use of gamma camera scintigraphy with technetium-99m hexakis-2-methoxyisobutylisonitrile (99mTc-MIBI) for assessment of the response of high-grade osteosarcoma to preoperative chemotherapy was evaluated. Twelve patients with osteosarcoma of the extremities underwent planar examination with 99mTc-MIBI before and after preoperative chemotherapy according to the recommendations of the Scandinavian Sarcoma Group. After calculating a quotient for the tumour and the average activity of both extremities and correcting for background activity, the change in uptake between the two examinations was assessed. This was compared with histological examination of the ultimately resected specimen in 11 patients and progressive clinical disease in one. All the 11 tumours undergoing histological examination showed cellular necrosis of between 50% and 100% as well as a reduced uptake of 99mTc-MIBI, while the single progressive tumour showed an increased uptake. There was a correlation between the reduction of radiopharmaceutical uptake and the histological response in the entire series, while the variation was too large to allow conclusions in individual patients. This variation may have biological reasons or may be due to the planar imaging technique, which only allows semiquantitative evaluation. The technique reflects response to therapy but is not yet clinically applicable for the identification of poor responders, which would serve as a basis for alteration of the chemotherapy regimen. In order to evaluate whether such a role could be fulfilled, further studies using single-photon emission tomography with correction for attenuation and scattering of photons are necessary.

Posterior decompression and stabilization for spinal metastases. Analysis of sixty-seven consecutive patients

The neurological function, survival, and rehabilitation of sixty-seven consecutive patients who had been managed operatively for spinal metastases with epidural compression were assessed. The epidural compression was in the thoracic spine in forty-one patients and in the lumbar spine in twenty-six. According to the system of Frankel et al. for the assessment of neurological function, twenty-six patients had a major neurological deficit (grade B or C), thirty-two had a minor deficit (grade D), and nine had no deficit (grade E). None of the patients had an operation to treat a pathological vertebral fracture without epidural compression. The operative treatment included wide decompression through a posterior approach followed by stabilization without bone-grafting. A Cotrel-Dubousset device was used in thirty-two patients; an Olerud posterior fixator, in sixteen; an Isola device, in twelve; and another device, in seven. The most common complication was wound infection (eleven patients). There were no perioperative or immediate postoperative deaths (within fourteen days). The rate of survival was 51 per cent (thirty-four of sixty-seven) at six months and 22 per cent (fifteen of sixty-seven) at twelve months. Over-all, forty-four of the fifty-eight patients who had had a neurological deficit preoperatively had complete or partial neurological recovery within the first two weeks postoperatively. The nine patients who had not had a neurological deficit preoperatively retained normal neurological function postoperatively. Thirty-eight of the forty-four patients who were alive at three months and twenty-nine of the thirty-four who were alive at six months were still able to walk. Thirty-nine of the forty-nine patients who survived more than two months were able to return home for a median of seven months. Fourteen patients had a reoperation on the spine. Six of these patients had recurrent epidural compression at another level of the spine, and five had recurrent compression at the previously treated level. Three patients had a reoperation because of loosening of the implant. The results of this study suggest that neurological function can be maintained or improved by decompression and stabilization through a posterior approach as treatment for spinal metastases.

Incorporation of β-Galactosidase-Expressing Endothelial Cells into the Skeletal Muscle Microvascular Bed of Mice

Cloned murine endothelial cells (cEC) were used as a carrier system for introducing a foreign gene into the microvascular bed of the hind limb of inbred mice. cEC were transfected with a β-galactosidase-neo fusion construct, which enables both selection for DNA uptake in the presence of G 418 and the staining of cells for β-galactosidase activity. Transfected cEC adhered and integrated readily into confluent monolayers of nontransfected cEC (up to 26% of total cell number). Seeding lacZ-transfected cEC on explanted arteries revealed rapid adhesion of the cells (within minutes) to the intact endothelium. After injection of 106transfected EC via the femoral artery into the microvascular bed of the hind limb their presence was documented by β-galactosidase staining after various time periods (1 h to 4 wk). Implanted cEC were detected in numerous elements of the microcirculation both in frozen sections and in squash preparations of the hind limb muscle and in the femoral bone up to 4 wk after the injection. The microvascular bed of skeletal muscle of the mouse as a recipient site for transduced syngeneic endothelial cells is, thus, a suitable experimental model to study various strategies for somatic gene therapy. Copyright © 1997 Elsevier Science Inc.

Expression of a chemotactic cytokine (MCP-1) in cerebral capillary endothelial cells in vitro

A full-length cDNA encoding the porcine monocyte chemoattractant protein-1 (pMCPC-1) was isolated from growth-stimulated porcine cerebral capillary endothelial cells (cEC); the pMCP-1 cDNA showed 89% identity to human MCP-1 and was isolated by use of subtractive hybridization and differential screening of two phenotypically different sub-populations of cloned cEC. pMCP-1 was abundantly expressed in cEC grown in the presence of FCS, ECGF and heparin whereas lower expression was observed in cEC kept in FCS-supplemented medium only. As shown by Northern blot analysis, no pMCP-1 transcripts were present in total RNA derived from freshly isolated brain capillaries, large brain vessels or whole brain homogenate. MCP/JE expression was also demonstrated in ECGF/heparin-treated murine cEC. Astrocytes and smooth muscle cells grown in FCS-supplemented medium did not show MCP-1 expression. Treatment of porcine cEC with TNF-alpha increased pMCP-1 mRNA levels in a dose-dependent manner. These data further support the notion that cerebral capillary endothelial cells actively participate in processes of CNS host defense.

Reconstruction in metastatic destruction of the acetabulum. Support rings and arthroplasty in 12 patients

In 12 patients with acetabular metastases, we reconstructed the hip with a support ring, cement, and Charnley prosthesis with a 22 mm head. There were no immediate postoperative deaths or cardiovascular complications. Dislocations occurred in 5 patients, 1 of whom required open reduction. At follow-up, 3 patients were alive 11, 15, and 18 months after surgery. 9 patients died after 8 (2-13) months. All patients obtained relief from pain, became ambulatory and were discharged to their homes. 1 patient had rapid disease progression with pathologic fracture and cranial dislocation of the support ring. Among the remaining 11 patients, the hip has not again caused pain or limited function. There were no signs of loosening, except in the patient with fracture of the hemipelvis. Remineralization was observed in 2 breast cancer patients after chemotherapy. Hip reconstruction can restore painless function until death in cancer patients with severe destruction of the acetabulum.

Cytological diagnosis of bone tumours

We evaluated the diagnostic accuracy of fine-needle aspiration biopsy in a prospective study of 300 patients with previously undiagnosed bone lesions. Patients with suspected local recurrence of a primary bone tumour or a metastatic lesion of a previously diagnosed malignancy were excluded. Fine-needle aspiration biopsy was performed under radiological control as an outpatient procedure. The series was grouped into three major categories: 1) benign bone lesions including infections; 2) primary malignant bone tumours; and 3) metastases including lymphomas and myelomas. We compared the cytological diagnosis with the final diagnosis as assessed by histological examination and/or the clinical and radiological features. Material considered conclusive for cytological diagnosis was obtained from 251 of the 300 patients. Of the 49 failures, there were 24 aspirates with insufficient cellular yield and 25 in which a diagnosis could not be made although the cytological material was adequate in quantity. Most of the inconclusive aspirates (36/49) were obtained from benign bone lesions. The diagnosis was correct in 239 (95%) of the 251 cases providing adequate cytological material. There were eight (3%) falsely benign diagnoses, one (0.3%) falsely malignant, and three cases in which we were unable to differentiate between sarcoma and a metastasis. Chondrosarcoma (2/12) gave the greatest diagnostic difficulty and Ewing's sarcoma the least (0/9). There were no decisive errors of treatment. All falsely benign or malignant diagnoses were questioned, and led to open biopsy since they did not correlate with the clinical and radiological features. Our study suggests that fine-needle aspiration biopsy is a valid option for the diagnosis of bone tumours. It is a simple outpatient procedure which gives sufficient cytological material for the correct diagnosis in 80% of cases. As with histological analysis of material from open biopsy, the cytological assessment must agree with the clinical and radiological findings.

Sequence of the porcine full-length cDNA encoding ribosomal protein rpS12

The full-length cDNA encoding the porcine ribosomal protein rpS12 was shown to be differentially expressed in endothelial and smooth muscle cells. A cDNA clone containing the entire rpS12 sequence was isolated from growth-stimulated capillary endothelial cells by use of subtractive hybridization and differential screening. The porcine rpS12 cDNA coding region exhibits 94% identity to the rat rpS12 and 92% to the human rpS12 cDNAs.

Low risk of recurrence of enchondroma and low-grade chondrosarcoma in extremities. 80 patients followed for 2-25 years

We analyzed the clinical course in 40 patients with enchondroma and 40 with low-grade chondrosarcoma of the extremities after a median follow-up of 7 years. 13 patients with enchondroma and 2 with chondrosarcoma had only open biopsy and they had no signs of further progression of the lesions. Among 23 patients with enchondroma and 23 with chondrosarcoma who were treated by intralesional curettage, 3 had local recurrences. The 10-year local recurrence rate was 0.04 in the enchondroma group and 0.09 in the chondrosarcoma group. There were no metastases. The results imply that enchondroma and low-grade chondrosarcoma of the extremities should be treated with limited surgery. The morbidity associated with en bloc resection and reconstruction can apparently be obviated without jeopardizing the limb or survival.

Ontogenic expression of the erythroid-type glucose transporter (Glut 1) in the telencephalon of the mouse: correlation to the tightening of the blood-brain barrier

Since Glut 1 was shown to be highly abundant in brain microvessels, its distribution during early developmental stages seems of importance in respect to the timing of blood-brain barrier (bbb) formation in the developing CNS. Here we have followed the temporal expression of the erythroid-type glucose transporter Glut 1 in the telencephalon of the embryonic and newborn mouse, beginning at the 9th intrauterine day. Glut 1 immunofluorescence staining was done on cryosections using a rabbit polyclonal antiserum to purified human erythrocyte glucose transporter. Endothelial cells resp. capillaries were detected by staining with a rhodamin-coupled Bandeiraea simplicifolia lectin (BSL). In parallel, the developmental tightening of the embryonic bbb was assessed by perfusion of mouse embryos with Trypan blue and horse radish-peroxidase. At E9, prior to the onset of intraneural neovascularization, strong Glut 1 immunoreactivity was found in the whole neuroectoderm but only minor staining was seen in the perineural domain. Glut 1 expression remained uniformly distributed in the intraneural tissue at E10, the beginning of intraneural neovascularization in the mouse. From E11 onwards, Glut 1 immunoreactivity was invisible in neuroepithelial cells, but appeared tightly associated with intraneural capillaries. Perfusion of E12 embryos using trypan blue solution and HRP revealed that most parts of the CNS and spinal cord were impermeable to the tracer substances at that stage. Thus, we suggest that the bbb is established very early in CNS development, probably in the course of intraneural neovascularization. In addition, our data indicate that the restriction of Glut 1 expression to the intraneural capillaries reflects the onset of bbb function in the mouse embryo.

Survival after surgery for spinal and extremity metastases. Prognostication in 241 patients

We assessed the survival after surgery in 153 patients with extremity metastases and 88 with spinal metastases. The survival rate for the whole series of 241 patients was 0.30 at 1 year, 0.15 at 2, and 0.08 at 3 years. The 1-year survival rate was the same for the extremity metastases group and the spinal group. Univariate analysis showed that 1-year survival was related to metastatic load, site of primary tumor, and presence of pathologic fracture. Multivariate regression analysis showed that pathologic fracture, visceral or brain metastases, and lung cancer were negative prognostic variables. Solitary skeletal metastases, breast and kidney cancer, myeloma, and lymphoma were positive variables. A prognostication model based on these variables stratified the patients into 3 groups with a 1-year survival ranging from 0.5 to 0.0. These prognostic variables can be used for differentiating the treatment of cancer patients with pathologic fracture or epidural compression.

Giant-cell tumours with fracture at diagnosis. Curettage and acrylic cementing in ten cases

Between 1971 and 1991 we treated 98 patients with giant-cell tumours, 15 of whom presented with a pathological fracture. They were most common around the knee (12). Nine fractures were intra-articular. The tumours were treated by curettage and acrylic cementing (10), excision and endoprosthesis (1), excision and allograft (1), curettage and autologous graft (2) or by resection of the fibular head (1). Four patients had local recurrence, three of whom were cured by repeat curettage and cementing. Pathological fracture through a giant-cell tumour is not a contraindication to treatment by curettage and acrylic cementing.

Giant-cell tumours with fracture at diagnosis. Curettage and acrylic cementing in ten cases

Between 1971 and 1991 we treated 98 patients with giant-cell tumours, 15 of whom presented with a pathological fracture. They were most common around the knee (12). Nine fractures were intra-articular. The tumours were treated by curettage and acrylic cementing (10), excision and endoprosthesis (1), excision and allograft (1), curettage and autologous graft (2) or by resection of the fibular head (1). Four patients had local recurrence, three of whom were cured by repeat curettage and cementing. Pathological fracture through a giant-cell tumour is not a contraindication to treatment by curettage and acrylic cementing.

Near-haploidy in two malignant fibrous histiocytomas

Cytogenetic analysis of two malignant fibrous histiocytomas (MFH) revealed near-haploid clones in both tumors. One tumor had only 23 chromosomes, the lowest chromosome number so far detected in human neoplasia, and showed several structural rearrangements: 23, X, der(1)t(1;?;8)(q42;?;q13), +del(7)(p11),der(8)t(8;13)(q13;q12), inv(9)(p24q21), r(10)(p15q26), -13, der(14)t(14;22)(p13;q11), -15, +r. The other MFH had only numerical changes: 28,X, +5, +18, +20, +21, +22/56, idemx2. With the present two cases, four of 78 MFHs studied in our laboratory have been near-haploid, suggesting that this otherwise rare phenomenon in neoplasia may be relatively common in MFH.

Heterogeneity of smooth muscle-associated proteins in mammalian brain microvasculature

In the brain, the microvascular system is composed of endothelial cells surrounded by a layer of pericytes. The lack of smooth muscle cells in this tissue suggests that any contractile function must be performed by one or both of these cell types. The present study was undertaken in order to identify cells in terminal blood vessels that contain smooth muscle-like contractile machinery. Endothelial cells were reactive with antibodies against smooth muscle myosin but showed no other smooth muscle-related features. In contrast, pericytes of intact microvessels showed a pattern of protein expression similar to that of smooth muscle cells. Pericytes also behaved in tissue culture like cultured smooth muscle cells, with regard to the changes in expression of smooth muscle-related proteins. These data confirm the close relationship between smooth muscle cells and pericytes, and point to their contractile function in the brain microvessels.