Expression of p27/Kip1 is down-regulated in human prostate carcinoma progression

p27(Kip1) is a cyclin-dependent kinase inhibitor whose down-regulation has been observed in several tumour models, including breast, colorectal, and gastric carcinomas. The purpose of this study was to assess p27(Kip1) protein expression in normal and benign prostatic epithelia as well as the possible existence of abnormalities in prostate carcinoma progression. p27(Kip1) expression was immunohistochemically analysed in 51 normal tissue samples, 11 nodular hyperplasias (NH), 22 high-grade prostatic intraepithelial neoplasias (PIN), 56 localized prostate adenocarcinomas, and 19 metastases. Immunoblotting was performed in ten cases. Normal prostate epithelium and NH showed diffuse and intense p27(Kip1) nuclear expression in most cases. A significant p27(Kip1) down-regulation was observed in many carcinomas when compared with benign epithelium. Forty-seven cases (84 per cent) were low p27(Kip1) expressors (<50 per cent positive cells) and nine cases (16 per cent) were high p27(Kip1) expressors. p27(Kip1) down-regulation was also consistently seen in PIN. Fourteen out of 19 metastases (74 per cent) were low p27(Kip1) expressors. Six metastatic samples had their corresponding primary tumour analysed and three cases showed decreased expression in the metastasis. It is concluded that p27(Kip1) is constitutively expressed in normal and benign prostatic tissue. This expression is clearly down-regulated in neoplastic progression from the preinvasive lesions through invasive carcinoma and metastases and this therefore occurs in early stages of neoplastic transformation.

Effects of hexose pentaacetates on electrical activity and cytosolic Ca2+ in mouse pancreatic islets

Electrical activity of beta-cells and cytosolic Ca2+ concentration ([Ca2+]i) were monitored in mouse pancreatic islets exposed to the pentaacetate esters of alpha-D-glucose, beta-D-galactose and beta-L-glucose, all tested at 1.7 mM concentration. In the presence of 5 mM D-glucose, alpha-D-glucose pentaacetate induced electrical activity and increased [Ca2+]i, whilst beta-D-galactose pentaacetate failed to do so. The electrical and cationic response to the D-glucose ester occurred with a delay of between 5 and 10 min, the ester-induced increase in [Ca2+]i being suppressed in the absence of extracellular Ca2+. As a rule, beta-L-glucose pentaacetate also failed to evoke biophysical responses in the islets exposed to 5 mM D-glucose. However, in the presence of 10 mM L-leucine the L-glucose ester induced electrical activity. These findings, which parallel the insulinotropic action of the same esters in rat pancreatic islets reinforce the view that the positive insulinotropic action of selected hexose pentaacetates cannot be attributed to the catabolism of their acetate moiety but, instead, involves a dual mode of action linked to both the metabolism of their carbohydrate moiety and a direct effect of the ester itself upon a yet unidentified receptor system. Furthermore, this study provides the first evidence that the latter direct effect results in the induction of both electrical activity and [Ca2+]i oscillations.

Rapid insulinotropic effect of 17beta-estradiol via a plasma membrane receptor

Impaired insulin secretion is a hallmark in both type I and type II diabetic individuals. Whereas type I (insulin-dependent diabetes mellitus) implies ss-cell destruction, type II (non-insulin dependent diabetes mellitus), responsible for 75% of diabetic syndromes, involves diminished glucose-dependent secretion of insulin from pancreatic beta-cells. Although a clear demonstration of a direct effect of 17beta-estradiol on the pancreatic ss-cell is lacking, an in vivo insulinotropic effect has been suggested. In this report we describe the effects of 17beta-estradiol in mouse pancreatic ss-cells. 17beta-Estradiol, at physiological concentrations, closes K(ATP) channels, which are also targets for antidiabetic sulfonylureas, in a rapid and reversible manner. Furthermore, in synergy with glucose, 17beta-estradiol depolarizes the plasma membrane, eliciting electrical activity and intracellular calcium signals, which in turn enhance insulin secretion. These effects occur through a receptor located at the plasma membrane, distinct from the classic cytosolic estrogen receptor. Specific competitive binding and localization of 17beta-estradiol receptors at the plasma membrane was demonstrated using confocal reflective microscopy and immunocytochemistry. Gaining deeper knowledge of the effect induced by 17beta-estradiol may be important in order to better understand the hormonal regulation of insulin secretion and for the treatment of NIDDM. receptor.

Collagenase-3 expression is associated with advanced local invasion in human squamous cell carcinomas of the larynx

Collagenase-3 (MMP-13) is a matrix metalloproteinase recently identified on the basis of differential expression in normal breast tissues and in breast carcinoma. To date, collagenase-3 expression has been reported only in breast carcinomas and in articular cartilage of arthritic patients; the presence and possible implication of this enzyme in the progression of other malignant tumours are unknown. In this study collagenase-3 mRNA expression has been analysed by northern blot in a series of 35 matched squamous cell carcinomas of the larynx and the corresponding adjacent non-neoplastic tissues. In addition, mRNA expression of membrane type 1-matrix metalloproteinase (MT1-MMP) and gelatinase A, two matrix metalloproteinases which have the ability to activate collagenase-3 in vitro, was also examined in the same cases. No collagenase-3 expression was detected in any of the 35 normal mucosae, but collagenase-3 mRNA was observed in 20 of the 35 carcinomas (57 per cent). Western blot analysis revealed the presence of collagenase-3 protein in those carcinomas with high levels of mRNA expression, whereas no protein was detected in the carcinomas with negative mRNA expression, or in any of the normal tissues. The protein was localized predominantly in tumour epithelial cells. Collagenase-3 expression correlated significantly with better histological differentiation of the tumours (p = 0.026), as well as with advanced local invasion (p = 0.026). Collagenase-3 upregulation was also significantly associated with MT1-MMP and gelatinase A overexpression. These findings suggest that collagenase-3 expression may contribute to the progression of a significant subset of squamous cell carcinomas of the larynx and that its coordinate overexpression with MT1-MMP and gelatinase A may have a cooperative effect in the progression of the tumours.

Albumin elicits calcium signals from astrocytes in brain slices from neonatal rat cortex

1. Albumin causes calcium signals and mitosis in cultured astrocytes, but it has not been established whether astrocytes in intact brain also respond to albumin. The effect of albumin on intracellular calcium concentration ([Ca2+]i) in single cells was therefore studied in acutely isolated cortical brain slices from the neonatal rat. 2. Physiological concentrations of albumin from plasma and from serum produced an increase in [Ca2+]i in a subpopulation of cortical cells. Trains of transient elevations in [Ca2+]i (Ca2+ spikes) were seen in 41 % of these cells. 3. The cells responding to albumin are identified as astrocytes because the neurone-specific agonist NMDA caused much smaller and slower responses in these cells. On the other hand NMDA-responsive cells, which are probably neurones, exhibited only small and slow responses to albumin. The residual responses of astrocytes to NMDA and neurones to albumin are likely to be due to crosstalk with adjacent neurones and astrocytes, respectively. 4. Methanol extraction of albumin removes a polar lipid and abolishes the ability of albumin to increase intracellular calcium. 5. Astrocyte calcium signalling caused by albumin may have important physiological consequences when the blood-brain barrier breaks down and allows albumin to enter the CNS.

cdc25 cell cycle-activating phosphatases and c-myc expression in human non-Hodgkin's lymphomas

cdc25A, cdc25B, and cdc25C are a family of human phosphatases that activate the cyclin-dependent kinases at different points of the cell cycle. cdc25A and cdc25B have been shown to have oncogenic potential, and they have been identified as transcriptional targets of c-myc. To determine the role of cdc25 genes in the pathogenesis of human lymphomas and their possible correlation with c-myc deregulation, we have analyzed the expression of cdc25A, cdc25B, and cdc25C and c-myc genes in a series of 63 non-Hodgkin's lymphomas and 8 nonneoplastic lymphoid tissues. The mRNA levels of the three phosphatases in the nonneoplastic tissues were negative or negligible. cdc25B overexpression was detected in 35 tumors (56%). This overexpression was more frequently found in aggressive (81%) than in indolent lymphomas (36%; P < 0.01). cdc25B overexpression was also significantly associated with a higher proliferative activity of the tumors. No cdc25B gene amplification or rearrangements were detected by Southern blot analysis. A biallelic EcoRI polymorphism of cdc25B gene was identified with a similar distribution in patients with lymphoma and in a normal population. cdc25A was overexpressed in three aggressive lymphomas. No detectable cdc25C mRNA levels were seen in any of the tumors. c-myc was overexpressed in 43% of tumors, and it correlated significantly with the presence of cdc25B up-regulation. Twenty-six of 35 (74%) lymphomas with high levels of cdc25B mRNA also showed c-myc overexpression, whereas 27 of 28 (96%) tumors without detectable or with very low cdc25B expression also had undetectable c-myc levels (P < 0.0001). In addition, a significant linear correlation was found between the cdc25B and c-myc mRNA levels (r = 0.575, P < 0.001). These findings suggest that cdc25B overexpression in non-Hodkin's lymphoma may participate in the pathogenesis of aggressive variants, and it may cooperate with c-myc oncogene in the development of these tumors.

p21WAF1/Cip1 is associated with cyclin D1CCND1 expression and tubular differentiation but is independent of p53 overexpression in human breast carcinoma

p21WAF1/Cip1 is an inhibitor of cdk/cyclin complexes, and thus regulates the cell cycle. p21 is also related to cell differentiation and is regulated by wild-type p53, although p53-independent regulatory pathways have been proposed. In order to analyse p21 expression as well as its relationship with p53 in human breast cancer, an immunohistochemical analysis was undertaken of 77 breast carcinomas, 16 of them with an in situ component; 30 adjacent normal tissue samples; and five non-neoplastic specimens. Forty-four infiltrating carcinomas (57 per cent) were p21-positive. Expression of p21 was also observed in pre-invasive lesions, whereas normal ducts were negative or focally and weakly positive. p21 expression was associated with high histological grade (II + III) (P = 0.017) and poor tubule formation (P = 0.002), and was significantly less frequent in lobular carcinomas (P = 0.0001). p21 positivity also correlated with increased proliferation, but this seemed to be dependent on the histological grade. Twenty carcinomas (26 per cent) showed p53 overexpression, but this was not associated with p21 negativity, suggesting the existence of p53-independent mechanisms for p21 regulation in vivo. Cyclin D1CCND1 expression was analysed in the same series and an association between p21 and cyclin D1 expression was found, since 23 of 26 cyclin D1-positive carcinomas were p21-positive (P < 0.001 ...). In conclusion, p21 is frequently overexpressed in breast carcinomas and this occurs in the early stages of neoplastic progression. This overexpression seems to be independent of p53 status and might be involved in cyclin D1 modulation.

Cancer dissemination during laparoscopic surgery: tubes, gas, and cells

Port-site metastasis has been an unexpected finding after laparoscopic surgery in gastrointestinal cancer patients. No clear explanation exists for this phenomenom. The aims of this study were to evaluate the dissemination pattern in an experimental model of hepatocarcinoma in the rat and summarize current knowledge about the risks and the results of experimental studies on cancer dissemination during laparoscopic surgery. NDA-induced hepatocarcinoma was obtained in Sprague-Dawley rats. Tumors were manipulated during laparoscopy (group 1, n = 11) or laparotomy (group 2, n = 12). A Medline review of all experimental studies about the risk of cancer dissemination during laparoscopic surgery was undertaken. Both models were associated with implants in parietal wounds [1/11 in group 1 (9%) vs. 1/12 in group 2 (8%), p = NS]. Analysis of the current literature confirms that laparoscopy is associated with abdominal cell mobilization, and cells can be recovered in trocars, filtered exhaust gas, and instruments. Postoperative immunosuppression, the biologic aggressiveness of the tumor, and the gas used for laparoscopy also influence tumoral growth. Port-site metastases are secondary to multiple factors, including the technical skill of the surgeon, the biologic properties of the tumors, and local environmental aspects. Undoubtedly, laparoscopy can help disseminate aggressive tumors and should be reserved for diagnostic and staging procedures or for treatment of low-grade malignant tumors. Therapeutic resection, especially of colon cancer, should be restricted to prospective and randomized trials until there are enough hard data to rule out the clinical importance of this potentially severe complication.

Actions of serum and plasma albumin on intracellular Ca2+ in human endothelial cells

1. The effects of serum and plasma albumin on [Ca2+]i in human endothelial cells were examined using single-cell Ca2+ imaging. Two types of endothelial cell were used: human umbilical vein endothelial cells (HUVEC) in primary culture, and the endothelial-derived cell line ECV304. 2. Serum albumin caused a large and transient rise in [Ca2+]i, due to Ca2+ release from an IP3-sensitive internal store, followed by a maintained elevation in [Ca2+]i attributable to Ca2+ influx from the external medium. A half-maximal rise in [Ca2+]i was produced by a concentration of serum albumin of about 1 microgram ml-1. 3. The Ca(2+)-releasing action of serum albumin is abolished by methanol extraction and is therefore attributable to an attached polar lipid. A possible candidate is lysophosphatidic acid, known to be released from platelets during blood coagulation, which produced similar effects to those of serum albumin. 4. In HUVEC, plasma albumin caused a sustained decrease in [Ca2+]i from the mean resting level of 114 nM to 58 nM. No effect of plasma albumin was observed in ECV304 cells. 5. The decrease in [Ca2+]i caused by plasma albumin is due to an uptake into intracellular stores. The store loading substantially potentiates the action of Ca(2+)-releasing agonists such as histamine. 6. The results show that normal plasma albumin, which carries few lipids, lowers [Ca2+]i and potentiates the actions of Ca(2+)-releasing agonists by promoting Ca2+ uptake into intracellular stores. When converted to the serum form, by binding lysophosphatidic acid released during blood coagulation, albumin has a potent effect in elevating [Ca2+]i. Blood coagulation may therefore play a role in regulating vascular tone and capillary permeability.

[Ischemic heart disease and postoperative mortality in major vascular surgery. An up-to-date diagnostic approach]

BACKGROUND

The aim of this study is to evaluate the efficacy the dobutamine stress echocardiography in predicting the perioperative cardiac risk of patients undergoing major vascular surgery.

METHODS

Seventy-seven consecutive and not selected patients, undergoing a surgical treatment requiring aortic cross clamping, were assessed also with a transthoracic dobutamine stress echocardiography. With electrocardiographic and echocardiographic monitoring ventricular ischemia or wall motion abnormalities, 5 micrograms/kg per min of chlorhydrate dobutamine for 5 minutes were infused, followed by other 10 micrograms/kg per min increased up to 40 micrograms/kg per min. During the last 4 minutes 0.25 mg of atropin were infused increasingly up to 1 mg.

RESULTS

Of all these patients, 26 had a stress ischemia but only 4 cases underwent a coronary angiography and only 2 of these underwent a preventive myocardial revascularization. Due to poor cardiac conditions pointed out with the dobutamine stress, 3 patients were not treated surgically. With an aggressive intra- and perioperative monitoring 73 patients underwent a surgical treatment: they were 28 aorto-bifemoral, 3 aorto-aortic grafts, 1 aorto-bisiliac thoraco-abdominal interposition graft, and 20 aorto-bifemoral, 4 aorto-femoral, 1 aorto-aortic thoraco-abdominal, 1 aorto-renal by-pass and 7 aorto-iliac-femoral thromboendoarterectomies. In the postoperative period 4 cardiac ischemic complications and 2 deaths (2.5%) were observed.

CONCLUSIONS

According to our personal opinion, stress echocardiography can be considered a test with a excellent feasibility and safety rate, not expensive and with a good reproducibility and reliability. It allowed to predict the cardiac risk in our patients suggesting not only the surgical but also the anesthesiologic and the perioperative therapeutic management.

p21WAF1/Cip1 expression is associated with cell differentiation but not with p53 mutations in squamous cell carcinomas of the larynx

p21WAF1/Cip1 is a recently identified gene involved in cell cycle regulation through cyclin-CDK-complex inhibition. The expression of this gene in several cell lines seems to be induced by wild-type, but not mutant, p53. p21WAF1/Cip1 expression has been studied at both mRNA and protein levels in a series of 49 normal mucosae and squamous cell carcinomas of the larynx. A significant association was found between mRNA and protein expression in tumours (P < 0.0001). p21WAF1/Cip1 expression was strongly associated with squamous cell differentiation of carcinomas, because six of seven (86 per cent) undifferentiated carcinomas (grade 4) showed very low levels of p21WAF1/Cip1 expression, whereas 41 out of 42 (98 per cent) carcinomas with squamous cell differentiation (grades 1-3) had normal or high levels of p21WAF1/Cip1 expression (P < 0.0001). In addition, p21WAF1/Cip1 expression was topologically related to the squamous differentiation of tumour cells with a distribution similar to that seen in normal squamous epithelium. No correlation was found between p21WAF1/Cip1 expression and the global S-phase of the carcinomas. p53 mutations (exons 5-9) were found in ten carcinomas with p21WAF1/Cip1 expression, but no p53 mutations were detected in three p21WAF1/Cip1-negative tumours. In conclusion, p21WAF1/Cip1 expression is frequently upregulated in squamous cell carcinomas of the larynx and is associated with tumour cell differentiation. p21WAF1/Cip1 expression in these tumours is independent of p53 gene mutations.

p16MTS1/CDK4I mutations and concomitant loss of heterozygosity at 9p21-23 are frequent events in squamous cell carcinoma of the larynx

We have examined the presence of p16MTS1/CDK4I gene deletions, mutations and methylation status, and 9p21-23 deletions in a series of 46 squamous cell carcinomas of the larynx and paired normal mucosa previously characterized for cyclin D1 gene amplification and overexpression. pRb expression was also examined by immunohistochemistry. p16MTS1/CDK4I mutations were found in 10/46 (22%) carcinomas and hypermethylation in 2/31 (7%). Loss of heterozygosity at 9p21-23 was found in 24 out of 42 (57%) carcinomas examined. All p16MTS1/CDK4I mutated cases and the two hypermethylated carcinomas showed 9p21-23 loss of heterozygosity. The loss of heterozygosity correlated with advanced local invasion (P=0.0045), lymph node metastases (P=0.0326), stage IV of the tumors (P=0.0058), and existence of cyclin D1 amplification/overexpression (P < 0.03). Only one out of 37 carcinomas was negative for pRb expression. No alterations in p16 gene or 9p21-23 loss of heterozygosity were detected in this case. These findings indicate that p16MTS1/CDK4I is frequently inactivated by gene mutation, hypermethylation, and allelic deletions in a significant subset of squamous cell carcinomas of larynx. Since 9p21-23 loss of heterozygosity was more frequently detected than p16MTS1/CDK4I mutations, and mutated carcinomas invariably had loss of heterozygosity, allelic losses probably precede the p16MTS1/CDK4I mutations. Their association with cyclin D1 deregulation in advanced carcinomas could indicate a possible cooperative effect in the progression of these neoplasms.

Cyclin D1 and retinoblastoma gene expression in human breast carcinoma: correlation with tumour proliferation and oestrogen receptor status

Cyclin D1 (CCND1) and retinoblastoma (Rb) genes are cell cycle regulators which are altered in some breast carcinomas. However, the possible cooperation between CCND1 and Rb, as well as the influence and coincidence of their abnormalities in the proliferative capacity of mammary carcinoma cells in vivo, is still unknown. In order to assess both the significance of the CCND1 gene and Rb alterations in breast carcinomas and their relationship with the proliferative capacity of the tumours and other clinico-pathological factors, CCND1 mRNA expression was studied in 46 cases of primary breast carcinomas and matched normal tissue, 45 of which were also studied immunohistochemically, Rb expression was analysed in the same cases by immunohistochemistry, whereas the proliferative activity of the carcinoma was evaluated by flow cytometry. CCND1 mRNA was overexpressed in 19 tumours (41 per cent). Sixteen cases showed diffuse immunohistochemical expression, ten carcinomas had few positive cells, and 19 were absolutely negative. CCND1 mRNA and protein overexpression was associated with oestrogen receptor (ER) expression by the tumour. Interestingly, lack of ER expression was associated with a decreased CCND1 mRNA signal in non-overexpressed tumours. No association was observed between CCND1 mRNA or protein overexpression and tumour proliferation or other clinico-pathological parameters. Loss of Rb expression was observed in 26 per cent of the tumours. This abnormality was significantly associated with increased mean S-phase (P = 0.017) and decreased CCND1 mRNA expression in non-overexpressed tumours, supporting in vivo the postulated regulatory loop between Rb and CCND1 in vitro. We conclude that CCND1 up-regulation is not associated with increased proliferative activity in breast carcinomas, whereas its expression might be regulated in vivo by hormones and Rb. Loss of Rb expression is significantly associated with an increased proliferation of tumour cells, suggesting an important role in the progression of a subset of breast carcinomas, regardless of CCND1 abnormalities.

Plasma albumin induces calcium waves in rat cortical astrocytes

Changes in intracellular calcium were monitored in cultured cortical astrocytes stimulated with albumin. Albumin elicited intracellular calcium mobilisation from intracellular stores, inducing repetitive intracellular calcium oscillations. The oscillations were not blocked by ryanodine, a blocker of the Ca-induced Ca release mechanism, and the release occurred from the same store as is accessed by glutamate and bradykinin, both of which release calcium by an IP3-dependent mechanism. Calcium signals induced by albumin appear therefore to occur via a pure IP3-dependent mechanism. When albumin was applied to confluent monolayers of astrocytes, the oscillations in individual cells were initially unsynchronised, but after several minutes of application, the Ca2 oscillations were observed to synchronise and spread through the astrocyte network as a wave. These intercellular calcium waves were inhibited by the gap junction blocker halothane. Using the fluorescence recovery after photobleaching (FRAP) technique, we demonstrate that the development of propagated waves with prolonged exposure to albumin does not result from an increase in cell coupling. The development of calcium waves on exposure to albumin may be important in the formation of glial scars in the CNS after breakdown of the blood-brain barrier.

Hyperplastic lesions of the larynx. Experience of the Barcelona group

Squamous carcinoma of the larynx arises from pre-existing lesions, the so-called "preneoplastic lesions". Hyperplastic lesions represent a part of their spectrum, from both clinical and biological points of view. On morphologic grounds, the most characteristic feature with prognostic value in the evaluation of preneoplastic lesions is dysplasia. It is not only nuclear alterations that are seen in the process of malignant transformation, the cytoplasmic pattern of cytokeratins changes through neoplastic progression, with a progressive reduction of the molecular weight of the produced species. Dysplasia also associates with gross alterations of the DNA content. This is in agreement with our finding of alterations of genes participating in the control of the cell cycle, p53 and p21(WAF1/cip1). p53 overexpression is detected in non-invasive squamous lesions (even in the absence of obvious dysplasia) and p21(WAF1/cip1) shows a dramatic change in the pattern of expression in dysplastic epithelium compared with the normal. However, not all genes participating in the control of the cell cycle are altered in early lesions. Overexpression of cyclin D1, a common phenomenon in advanced carcinomas, is not likely to participate in the early phases of neoplastic development.

Adenosine 5'-triphosphate (ATP) receptors induce intracellular calcium changes in mouse leydig cells

Cytoplasmic calcium ([Ca(2+)](i)) changes evoked by adenosine 5(1)-triphosphate (ATP) were recorded in cultured individual Leydig cells within 10-18 h after cell dispersion. [Ca(2+)](i) was monitored using Fura-2AM loaded cells with a digital ratio imaging system. Five micromolars ATP induced biphasic [Ca(2+)](i) responses in most cells (94%,n=100), characterized by a fast increase from a basal level (126±5 nMSE,n=60 cells) to a peak (5-7 times above basal levels) within seconds, followed by a slow decrease toward a plateau level (2-3 times above basal) within 5 min. The peak phase of the [Ca(2+)](i) response increased with ATP concentrations (1-100 μM ATP) in a dose-dependent manner with an IC(50) of 5.9±1.2 μM, and it desensitized in a reversible manner with repeated application of 5 μM ATP at <5-min intervals. The [Ca(2+)](i) peak response was dependent on Ca(2+) release from an intracellular pool, whereas the plateau phase was dependent on extracellular [Ca(2+)]. ATP did not appear to induce formation of nonspecific membrane pores, since stimulation for 10 min with ATP (10-100 μM) in the presence of extracellular Lucifer yellow (LY) (5 mg/mL) did not result in dye loading of the cells. [Ca(2+)](i) transients were elicited by other adenosine nucleotides with an order of potencies (ATP>Adenosine diphosphate [ADP]>Adenosine> Adenosine monophosphate [AMP]) that was compatible with the expression of P(2) receptors. [Ca(2+)](i) responses were suppressed by the purinergic P(2) receptor antagonist, suramin. These results provide functional evidence for the expression of purinergic P(2) receptors in Leydig cells.

Albumin stimulates uptake of calcium into subcellular stores in rat cortical astrocytes

1. When albumin from either plasma or serum is applied at low concentrations to cortical astrocytes a decrease in the level of [Ca2+]i is observed. At higher concentrations trains of calcium spikes are seen. 2. Removal of the polar lipids which are normally bound to native albumin abolishes the ability to induce spikes, but the decrease in [Ca2+]i is unaffected. The decrease is abolished by the denaturation of albumin and is not reproduced by a number of other proteins, and is therefore a specific action of albumin. We conclude that native albumin has a dual agonist action: the decrease in [Ca2+]i is induced by the albumin protein molecule, while the spikes are induced by a lipid normally bound to it. 3. The decrease is rapid (fastest tau = 12 s) and the rate is dependent on the concentration of albumin. [Ca2+]i falls from 77 nM to around 34 nM in the presence of saturating levels of albumin, and this level appears to be maintained indefinitely. 4. The decrease is due to an uptake of calcium into subcellular stores, as it is not abolished by removal of external Ca2+ or Na+ but is abolished by thapsigargin and cyclopiazonic acid, which are specific inhibitors of the endoplasmic reticulum Ca(2+)-ATPase. 5. When the state of store filling after albumin application is probed with a pulse of glutamate it can be seen that stores fill with the same time course as the decrease in [Ca2+]i. The low level of [Ca2+]i in albumin must therefore be maintained by a suppression of calcium influx rather than by a continued uptake into stores. 6. The calcium uptake potentiates the efficacy of low concentrations of calcium-releasing agonists such as glutamate and bradykinin by almost an order of magnitude. 7. A possible function for the calcium uptake caused by albumin is to potentiate the production of calcium spike trains by promoting refilling of calcium stores in the intervals between spikes. The uptake may play a role in the response of astrocytes to damage in the CNS.

Detection of the bcl-1 rearrangement at the major translocation cluster in frozen and paraffin-embedded tissues of mantle cell lymphomas by polymerase chain reaction

The t(11;14)(q13;q32) translocation and its molecular counterpart bcl-1 rearrangement are highly characteristic of mantle cell lymphomas (MCLs). Most of these translocations occur at the major translocation cluster (MTC) in a tight area that makes this rearrangement identifiable by the polymerase chain reaction (PCR). In this study, the specificity and sensitivity of the PCR technique in the identification of bcl-1 rearrangement and its suitability to amplify the t(11;14) MTC in fixed, paraffin-embedded tissues were analyzed. Genomic DNA was obtained from 21 MCLs and 1 chronic lymphocytic leukemia (CLL) with the t(11;14) translocation. The bcl-1 rearrangement was studied by Southern blot with the MTC, p94PS, and PRAD-1 probes. Polymerase chain reaction was performed using a JH consensus primer and specific primers for chromosome II in the MTC region. bcl-1 rearrangement was identified by Southern blot in the MTC in nine (43%) MCLs and in the p94PS region in the CLL. Polymerase chain reaction analysis of genomic DNA showed that the nine MCLs with MTC rearrangement also had an amplifiable band of the expected size (100%). No amplifiable products were detected in the negative MCLs or in the CLL. The specificity of the PCR products was confirmed by hybridization with an internal MTC oligonucleotide probe. Amplifiable DNA was obtained from the paraffin blocks of 7 cases with MTC rearrangement and 11 negative tumors. bcl-1 rearrangement was detected in this DNA of 6 positive MCLs (86%) by PCR and in none of the negative cases. In conclusion, this study demonstrates that the PCR technique is highly sensitive and specific for the detection of the bcl-1 rearrangement at the MTC. It can be used with both high molecular weight DNA and DNA obtained from formalin-fixed, paraffin-embedded tissues.

Activation of L-arginine transport (system y+) and nitric oxide synthase by elevated glucose and insulin in human endothelial cells

1. Modulation of L-arginine transport (system y+) and release of nitric oxide (NO) and prostacyclin (PGI2) by elevated glucose and insulin were investigated in human cultured umbilical vein endothelial cells. 2. Elevated glucose induced a time- (6-12 h) and concentration-dependent stimulation of L-arginine transport, which was reversible and associated with a 3-fold increase in intracellular cGMP accumulation (index of NO synthesis) and 75% decrease in PGI2 production. 3. Elevated glucose had no effect on the initial transport rates for L-serine, L-citrulline, L-leucine, L-cystine or 2-deoxyglucose. 4. Resting membrane potential was unaffected by elevated glucose whereas basal intracellular [Ca2+] increased from 65 +/- 5 nM to 136 +/- 16 nM. 5. Insulin induced a protein synthesis-dependent stimulation of L-arginine transport and increased NO and PGI2 production in cells exposed to 5 mM glucose. 6. In cells exposed to high glucose, insulin downregulated elevated rates of L-arginine transport and cGMP accumulation but had no effect on the depressed PGI2 production. 7. Our findings suggest that insulin's normal stimulatory action on human endothelial cell vasodilator pathways may be impaired under conditions of sustained hyperglycaemia.

Assessment of histopathologic changes in the colonic biopsy in acute graft-versus-host disease

The authors reviewed 78 colonic biopsies from 63 patients undergoing bone marrow transplantation (BMT), 56 allogeneic and 7 autologous, to assess different morphologic changes related with intestinal acute graft-versus-host disease (A-GVHD). Only five biopsies were done before the 20th day after BMT. The authors studied the presence of ulcers and atrophy in the mucosa, the nuclear atypia, and inflammatory infiltrate in the surface epithelium, and the architectural abnormalities, as well as dilation of the glands, and the presence of crypt abscesses. The authors explored the glandular epithelium for apoptosis and intraepithelial lymphocytes. They examined the lamina propria for inflammatory infiltrate, especially for so-called "focal periglandular infiltrate (FPGI)," edema fibrosis, increase of capillary vessels and presence of muciphages and clusters of enterochromaffin cells. Cases were grouped according to clinical symptoms and histologic diagnosis of A-GVHD in skin or liver. Group A had 15 asymptomatic cases (control). Group B had 20 cases from asymptomatic patients with a histologically proven A-GVHD. Group C had 43 cases with gastrointestinal symptoms and histologically proven A-GVHD. Then, the relative frequency of every histologic feature previously described were compared in the different groups by means of an univariate analysis. Apoptosis of the glandular epithelium was found in 48 cases, two of them in patients carrying an auto-BMT. Focal periglandular infiltrate was found in 11 cases that was associated with apoptosis (P < .03, Fisher's exact test). In this series, the presence of FPGI was linked with finding apoptosis in a given specimen with a probability of 91%. Glandular architectural changes and dilation were also more frequent in group C than in groups A and B when compared in the univariate analysis.

Plasma albumin is a potent trigger of calcium signals and DNA synthesis in astrocytes

Cells in the central nervous system are normally prevented from coming into contact with albumin and other protein components of blood by the existence of a tight blood-brain barrier. Astrocytes and other glial cells proliferate to form glial scars when the blood-brain barrier is breached. In this report we show that albumin is an important blood component responsible for inducing astrocyte proliferation. Albumin also generates maintained trains of calcium spikes in astrocytes. Neither activity depends on blood coagulation, as albumins from both serum and plasma are approximately equally effective. Methanol extraction of albumin abolishes both actions, and recombination of the methanol-extracted factor with extracted albumin restores full activity indistinguishable from that of native albumin. The factor is sensitive to lipase, and the solvent extraction profile is that of a polar lipid.

p53 expression in normal, dysplastic, and neoplastic laryngeal epithelium. Absence of a correlation with prognostic factors

p53 expression has been examined in 89 squamous cell carcinomas of the larynx (34 glottic, 28 supraglottic, 18 transglottic, 8 pyriform sinus, and 1 subglottic) obtained from 88 patients surgically treated in our centre. In addition, 59 laryngeal samples including normal respiratory epithelium and non-invasive squamous cell lesions were also tested. Frozen sections were immunostained with PAb 1801 and the results were correlated with pathological features, DNA ploidy and S-phase of the tumours, disease-free interval, and survival of the patients. p53 immunoreactivity was observed in 57 (64 per cent) carcinomas. None of the eight samples of normal respiratory epithelium was positive. p53-positive cells were seen in 8 of 23 (35 per cent) squamous cell metaplasias, 6 of 19 (32 per cent) low-grade dysplasias and 5 of 10 (50 per cent) high-grade dysplasias. No correlation was found between p53 expression in carcinomas and their clinical and pathological characteristics, DNA ploidy, or proliferative activity. Neither disease-free nor overall survival showed differences between p53-positive and p53-negative cases. These findings indicate that p53 may play a role in an early stage of malignant transformation of a subset of squamous cell carcinomas of the larynx, but seems not to be associated with further progression of the tumours.

Metabolic regulation of intracellular calcium concentration in mouse pancreatic islets of Langerhans

Intracellular Ca2+ concentration ([Ca2+]i) handling during K(+)-induced Ca2+ loads was studied in single islets of Langerhans. K(+)-induced depolarization caused a rapid and transient rise in [Ca2+]i. After K+ removal [Ca2+]i declined with a time course usually fitted by the sum of two exponential functions. Partial Na+ removal increased the resting [Ca2+]i level, indicating the existence of a Na+/Ca2+ exchange, but only slightly impaired the recovery from Ca2+ loads. Metabolic poisoning with CN- increased the resting Ca2+ level and slowed down the recovery from Ca2+ loads. Removal of external Na+ in islets poisoned with CN- strongly inhibited Ca2+ removal mechanisms. An increase in the glucose concentration from 0 to 16 mM (in the presence of diazoxide) resulted in a decrease in the resting [Ca2+]i and an acceleration of [Ca2+]i recovery from K+ loads. These results suggest that the main mechanism responsible for Ca2+ homeostasis is dependent on metabolic energy and that such energy can be provided by glucose metabolism.