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To ease water scarcity, dynamic programming, stochastic dynamic programming, and heuristic algorithms have been applied to solve problem matters related to water resources. Development, operation, and management are vital in a reservoir operating policy, especially when the reservoir serves a complex objective. In this study, an attempt via metaheuristic algorithms, namely the Harris Hawks Optimisation (HHO) Algorithm and the Opposite Based Learning of HHO (OBL-HHO) are made to minimise the water deficit as well as mitigate floods at downstream of the Klang Gate Dam (KGD). Due to trade-offs between water supply and flood management, the HHO and OBL-HHO models have configurable thresholds to optimise the KGD reservoir operation. To determine the efficacy of the HHO and OBL-HHO in reservoir optimisation, reliability, vulnerability, and resilience are risk measures evaluated. If inflow categories are omitted, the OBL-HHO meets 71.49% of demand compared to 54.83% for the standalone HHO. The HHO proved superior to OBL-HHO in satisfying demand during medium inflows, achieving 38.60% compared to 20.61%, even though the HHO may have experienced water loss at the end of the storage level. The HHO is still a promising method, as proven by its reliability and resilience indices compared to other published heuristic algorithms: at 62.50% and 1.56, respectively. The Artificial Bee Colony (ABC) outcomes satisfied demand at 61.36%, 59.47% with the Particle Swarm Optimisation (PSO), 55.68% with the real-coded Genetic Algorithm (GA), and 23.5 percent with the binary GA. For resilience, the ABC scored 0.16, PSO scored 0.15, and real coded GA scored 0.14 whilst the binary-GA has the worst failure recovery algorithm with 0.09., (© 2023. The Author(s).)

Purpose: To compare between deep neuromuscular blockade (NMB) and moderate NMB with respect to endoscopic surgical conditions and recovery profiles in patients with general anesthesia for transurethral resection of bladder (TURB)., Methods: 108 patients undergoing elective TURB were randomized into two groups: the moderate NMB (n = 54) or deep NMB (n = 54) group. After the operation, NMB was reversed with 2 mg/kg sugammadex at a train-of-four (TOF) count of 1 or 2 (moderate NMB group) or with 4 mg/kg sugammadex at post-tetanic count (PTC) of 2 (deep NMB group). Surgeons, who were blinded to the study design, rated the endoscopic surgical condition on a 5-point scale (1 = extremely poor, 2 = poor, 3 = acceptable, 4 = good, 5 = optimal) immediately following the operation. Recovery profiles, including postoperative residual curarization (PORC), respiratory complication, and recovery time, were recorded., Results: No difference was observed between the two groups regarding patients and anesthesia characteristics. There were statistically significant differences in endoscopic surgical conditions between the two groups (P < 0.001). Thirty-eight patients in the deep NMB group (74%) showed optimal surgical conditions, whereas 16 patients in the moderate NMB group (30%) showed optimal endoscopic surgical conditions. No PORC and respiratory complications occurred in both groups, and no difference was found between the two groups in terms of recovery profiles, including recovery time and other adverse events., Conclusions: Deep NMB and reversal with sugammadex improved the endoscopic surgical condition without complications compared with moderate NMB and reversal with sugammadex in patients undergoing TURB.

Background: Intraoperative use of a high-dose remifentanil may induce postoperative hyperalgesia. Low-dose naloxone can selectively reverse some adverse effects of opioids without compromising analgesia. We thus hypothesized that the intraoperative use of a high-dose remifentanil combined with a low-dose naloxone infusion reduces postoperative hyperalgesia compared with the use of remifentanil alone., Methods: Patients undergoing elective thyroid surgery were randomly assigned into one of three groups, depending on the intraoperative effect-site concentration of remifentanil, with or without a continuous infusion of naloxone: 4 ng ml-1 remifentanil with 0.05 μg kg-1 h-1 naloxone in the high-remifentanil with naloxone group, and 4 or 1 ng ml-1 remifentanil with a placebo in the high- or low-remifentanil groups, respectively. We measured the pain thresholds (primary outcome) to mechanical stimuli using von Frey filaments and incidence of hyperalgesia on the peri-incisional area 24 h after surgery. We also measured pain intensity, analgesic consumptions and adverse events up to 48 h after surgery., Results: The pain threshold presented as von Frey numbers [median (interquartile range)] was significantly lower in the high-remifentanil group (n=31) than in the high-remifentanil with naloxone (n=30) and the low-remifentanil (n=30) groups [3.63 (3.22-3.84) vs 3.84 (3.76-4.00) vs 3.80 (3.69-4.08), P=0.011]. The incidence of hyperalgesia was also higher in the high-remifentanil group than in the other groups [21/31 vs 10/30 vs 9/30, P=0.005]. Postoperative pain intensity, analgesic consumptions and adverse events were similar between groups., Conclusions: The intraoperative use of low-dose naloxone combined with high-dose remifentanil reduced postoperative hyperalgesia but not pain., Clinical Trial Registration: NCT02856087., (© The Author 2017. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com)

We studied the predictive performance of the Minto pharmacokinetic model during cardiopulmonary bypass in patients undergoing cardiac surgery. Patients received remifentanil target-controlled infusion using the Minto model during total intravenous anaesthesia with propofol. From 56 patients, 275 arterial blood samples were drawn before, during and after bypass to determine the plasma concentration of remifentanil, and the predicted concentrations were recorded at each time. For pooled data, the median prediction error and median absolute prediction error were 21.3% and 21.8%, respectively, and 22.1% and 22.3% during bypass. Both were 148.4% during hypothermic circulatory arrest and measured concentrations were more than three times greater than predicted (26.9 (17.0) vs. 7.1 (1.6) ng.ml -1 ). The Minto model showed considerable bias but overall acceptable precision during bypass. The target concentration of remifentanil should be reduced when using the Minto model during hypothermic circulatory arrest., (© 2017 The Association of Anaesthetists of Great Britain and Ireland.)

Background: Few studies investigated the optimal timing for tracheostomy and its influence on the clinical outcomes in critically ill pediatric patients. This study evaluated the differences in clinical outcomes between early and late tracheostomy in pediatric intensive care unit (ICU) patients., Methods: We assessed 111 pediatric patients. Patients who underwent a tracheostomy within 14 days of mechanical ventilation (MV) were assigned to the early tracheostomy group, whereas those who underwent tracheostomy after 14 days of MV were included in the late tracheostomy group. Clinical outcomes, including mortality, duration of MV, length of ICU and hospital stays, and incidence of ventilator-associated pneumonia (VAP) were compared between the groups., Results: Of the 111 pediatric patients, 61 and 50 were included in the early and late tracheostomy groups, respectively. Total MV duration and the length of ICU and hospital stay were significantly longer in the late tracheostomy group than in the early tracheostomy group (all P < 0.01). The VAP rate per 1000 ventilator days before tracheostomy was 2.6 and 3.8 in the early and late tracheostomy groups, respectively. There were no significant differences in mortality rate between the groups. No severe complications were associated with tracheostomy itself., Conclusions: Tracheostomy performed within 14 days after the initiation of MV was associated with reduced duration of MV and length of ICU and hospital stay. Although there was no effect on mortality rate, children may benefit from early tracheostomy without severe complications., (© 2016 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Sedation during diagnostic or therapeutic procedures must be safe and comfortable for patients. To achieve this, additional suitably qualified staff must be available throughout the procedure to administer sedation and monitor the patient. Anaesthesiologists possess the necessary knowledge and skills to perform sedation safely but are often unavailable. Non-anaesthesiologists performing sedation should be fully trained in the physiology of sedation, the pharmacology of sedatives and analgesics, the monitoring of patients, and in airway support, ventilatory care, and cardiopulmonary resuscitation. The presence of an anaesthesiologist is desirable when dealing with patients at high-risk of complications. Good sedation practice involves presedation assessment and optimal selection of patients, careful monitoring and support from dedicated staff, and adherence to recovery and discharge criteria.

Background: Hemophagocytic syndrome is characterized by nonmalignant histiocytes that undergo uncontrolled phagocytosis of normal hematopoietic cells. Clinical severity ranges from complete recovery to rapid deterioration and death., Case: Thrombocytopenia was discovered upon routine initial prenatal evaluation of a 24-year-old, gravida 2, para 1, at 29 weeks' gestation with a history of necrotizing lymphadenitis. Cytopenia and elevated transaminases developed, followed by hyperpyrexia. The patient delivered and her postpartum course was complicated by coagulopathy, multiorgan failure, and death. Bone marrow biopsy confirmed hemophagocytic syndrome., Conclusion: Early diagnosis of hemophagocytic syndrome during pregnancy might be helped by recognizing symptoms and signs, including a history of necrotizing lymphadenitis, and obtaining a bone marrow biopsy.

We report 5 cases of intravascular lymphoma (IVL) initially diagnosed by bone marrow aspiration and biopsy. Each patient had generalized symptoms; 1 also had neurologic deficits. CBC counts revealed anemia (4 patients), thrombocytopenia (4 patients), or mild leukopenia (1 patient). The bone marrow biopsy specimen was diagnostic in each case. Lymphoma cells were present in small groups or single file in sinusoids (in 1 patient, sinusoids were distended markedly by IVL) and were detected in bone marrow aspirate smears (4 patients) and peripheral blood smears (all patients). Immunohistochemical studies demonstrated that every neoplasm was of B-cell lineage, CD20+, positive for other B-cell antigens, and CD3- or CD43-. Immunophenotypic studies revealed at least 2, and possibly 3, distinct immunophenotypic groups of B-cell IVL: CD20+ CD5+ (3 neoplasms), CD20+ CD5- CD10+ (1 neoplasm), and CD20+ CD5- CD10 unknown (1 neoplasm). B-cell IVL may be detected by morphologic examination of peripheral blood and bone marrow, and involvement of these sites may be more common than is reported in the literature. Immunophenotypic studies are helpful in establishing the diagnosis and suggest that B-cell IVL is a heterogeneous group of neoplasms that may arise from more than 1 normal B-cell precursor.

The CD5 antigen is a T-cell associated marker that is also usually expressed by two B-cell neoplasms, chronic lymphocytic leukemia/small lymphocytic lymphoma and mantle cell lymphoma. We observed CD5 antigen expression in a subset of cases of intravascular large B-cell lymphoma (IVLBL), and we report here five cases. The patients, two men and three women, ranged in age from 59 to 81 years. Biopsy specimens were obtained from kidney, lung, bone marrow, abdominal wall, and neck, the latter involving a lymphangioma. All of the cases had histologic features typical of IVLBL, with large and atypical lymphoid cells located predominantly within blood vessels. Immunohistochemical studies performed using routinely fixed, paraffin-embedded tissue sections showed that the neoplastic cells were B cells, positive for the CD20 antigen and negative for the CD3 or CD43 antigens. All cases were also positive for the CD5 antigen. One case had an immunoglobulin heavy chain gene rearrangement shown by using a polymerase chain reaction method. The finding of CD5 antigen expression in a subset of IVLBL cases adds to other evidence in the literature suggesting that IVLBL is a heterogeneous entity. We considered the possibility that these cases were related to or represented unusual histologic forms of transformation from either chronic lymphocytic leukemia/small lymphocytic lymphoma or mantle cell lymphoma. All of the cases, however, were negative for the CD23 antigen and cyclin D1 (bcl-1) protein, which is evidence against this interpretation. The biologic significance of CD5 antigen expression in cases of IVLBL is uncertain. These neoplasms might arise from a separate lineage of CD5-positive B cells or from a specific, early stage of B-cell differentiation. Alternatively, some investigators have suggested that CD5 antigen expression by B cells is a marker of activation.

The stability of 2-AP, a chemoprotective agent, in various pH solutions and human gastric juice, the blood partition of 2-AP between plasma and blood cells, and the factors influencing the binding of 2-AP to 4% human serum albumin (HSA) were evaluated. 2-AP was stable in human gastric juice and pH solutions ranging from 1 to 12, however, 2-AP was unstable in pH 13 solution; the disappearance rate constant was 0.00759/h. 2-AP reached equilibrium rapidly between plasma and blood cells of rabbit blood. The equilibrium plasma/blood cells partition ratios were independent of initial rabbit blood concentrations of 2-AP, 1, 5, and 10 micrograms/ml; the values were in the range of 5.99-11.8. Binding of 2-AP to 4% HSA was dependent on HSA concentration, incubation temperature, 'the buffer' pH, and addition of acetylsalicylic acid. The binding of 2-AP was independent of buffers containing various concentrations of chloride ion, heparin, and alpha-1-acid glycoprotein.

A high-performance liquid chromatographic method was developed for the determination of a chemoprotective agent, 2-(allylthio)pyrazine (I), in human plasma and urine, and in rat blood and tissue homogenate using diazepam as an internal standard. The sample preparation was simple; 2.5 volumes of acetonitrile were added to the biological sample to deproteinize it. A 50-100 microl aliquot of the supernatant was injected onto a C18 reversed-phase column. The mobile phase employed was acetonitrile-water (55:45, v/v), and it was run at a flow-rate of 1.5 ml/min. The column effluent was monitored using an ultraviolet detector at 330 nm. The retention times for I and the internal standard were 4.0 and 5.1 min, respectively. The detection limits of I in human plasma and urine, and in rat tissue homogenate (including blood) were 20, 20 and 50 ng/ml, respectively. The coefficients of variation of the assay (within-day and between-day) were generally low (below 6.1%) in a concentration range from 0.02 to 10 microg/ml for human plasma and urine, and for rat tissue homogenate. No interferences from endogenous substances were found.

The pharmacokinetics of 2-(allylthio)pyrazine (2-AP) were evaluated after intravenous administrations of the drug to rabbits. The reason for the multiple peaks in the plasma concentration of 2-AP after intravenous administration of the drug to rabbits were also investigated. After intravenous administration of 2-AP, 10, 20, and 50 mg/kg, to rabbits, the pharmacokinetic parameters of 2-AP, such as the total area under the plasma concentration-time curve from time 0 to 12 h (261, 672, and 1190 micrograms min/ml), the total body clearance (38.3, 42.0, 44.6 ml/min/kg), and the percentages of intravenous dose of 2-AP excreted in 24 h as unchanged drug (0.0306, 0.0252, and 0.0492%), were independent of the dose ranges studied. Since the amount of 2-AP excreted in 12-h bile as unchanged drug after intravenous administration of 2-AP, 20 mg/kg, was only 0.0241 +/- 0.00156%, and some of 2-AP excreted in gastrointestinal tract as unchanged drug was reabsorbed, the reason for the appearance of multiple peaks after intravenous administration of 2-AP could be at least partly due to gastrointestinal excretion of the drug.

The antioxidant efficacy of aspalatone (APT; acetyl salicylic acid maltol ester), a new antiplatelet agent, has been characterized in vivo as well as in vitro, and several observations indicated that the antioxidant could prevent the neuroexcitation caused by oxidative stress. In this report, the effect of APT was evaluated on kainic acid (KA)-induced neurotoxicity, since the neurotoxicity induced by KA is, at least in part, mediated via the formation of free radicals. The results showed that pretreatments with APT or maltol (MAL) significantly attenuated seizure activity, oxidative stress (lipid peroxidation and protein oxidation) and the loss of hippocampal neurons induced by KA. On the other hand, the pretreatments with aspirin (ASP), ASP together with MAL or vitamin E failed to protect against the toxicity produced by KA suggesting that the mechanism of action for APT on the KA-induced neurotoxicity is different from that of ASP. These finding raise the possibility that salicylmaltol, a metabolite of APT, plays a role in preventing the neurotoxicity evoked by KA. Therefore, our results suggest that an APT-related antioxidant mechanism, which is linked to the MAL moiety, is involved in the neuroprotective effect against KA.

Homer Wright rosettes, typically found in neuroblastomas and consisting of neoplastic cells surrounding an eosinophilic fibrillary centre without a lumen, have been considered as an important finding in the differential diagnosis of small round cell tumours. Rosettes in a neoplasm involving lymph nodes or bone marrow traditionally excluded a diagnosis of malignant lymphoma. In this report, we describe three cases of malignant lymphoma (two small lymphocytic and one diffuse large cell) with pronounced rosette formation. One of the two cases of small lymphocytic lymphoma was observed in the bone marrow, the other small lymphocytic lymphoma and the large cell lymphoma were in lymph nodes. The rosettes consisted of neoplastic lymphoid cells, often with participation of reactive macrophages, and ultrastructurally they had a central mass of interdigitating fibrillary cytoplasmic projections. Two cases were of B-cell lineage and one was of T-cell lineage. To the best of our knowledge, this is the first report of T-cell lymphoma with rosettes. Based on these findings, it is suggested that non-Hodgkin's lymphoma be included in the differential diagnosis of rosette-forming round cell neoplasms.

Although numerous studies have demonstrated increased expression of p53 protein in the Reed-Sternberg cells of Hodgkin's disease, little data exist as to whether mutations of the p53 gene is a common occurrence in this neoplasm. Using a microdissection technique coupled with PCR, single-strand conformation analysis, and DNA sequencing, we studied 23 cases of Hodgkin's disease for mutations within exons 5 to 8 of the p53 gene. We found seven mutations within six cases; six were missense mutations. An identical missense mutation was found in three cases (codon 243, methionine to isoleucine), and another identical missense mutation was found in an additional two cases (codon 204, glutamic acid to lysine). Verification of the mutations was accomplished either by direct Southern blotting of PCR-amplified p53 exon products from re-extracted DNA or by hybridization of cloned PCR-amplified p53 exon products from re-extracted DNA with a mutant-specific oligonucleotide. There was no good correlation between the presence of p53 mutations and the level of p53 protein expression, which was found to be overexpressed in all cases, the level of MDM2 protein expression, or the proliferation rate as determined by K-67 antibody. None of the cases with p53 mutation had evidence of Epstein-Barr virus within the Reed-Sternberg cells, as compared with 7 of 17 of the other cases (p < 0.06). These results suggest that p53 mutation may represent an important mechanism in the pathogenesis of Hodgkin's disease, and this mechanism may be independent of Epstein-Barr virus.

We describe a case of simultaneous nodular sclerosing Hodgkin's disease and a granulocytic sarcoma in a cervical lymph node without any previous therapy. The condition evolved into acute myelogenous leukemia approximately 8 months after the initial diagnosis of the granulocytic sarcoma. The unexpected presence of a granulocytic sarcoma made the diagnosis challenging, and appropriate immunohistochemical studies were required for accurate diagnosis. To the best our knowledge, this is the first report of synchronous Hodgkin's disease and granulocytic sarcoma with eventual development of acute myelogenous leukemia.

Amyloid beta-protein, the principal constituent of amyloid fibrils found in senile plaques and blood vessels in Alzheimer's disease, is constitutively produced and released into medium of cultured cells. Amyloid beta-protein is derived by proteolysis of the beta-amyloid precursor protein by unclear mechanisms. Beta-amyloid precursor protein is a transmembrane protein which can be processed to release a large secretory product or processed in the endosomal/lysosomal pathway without secretion. Previous studies have shown that from the cell surface, beta-amyloid precursor protein may be released after cleavage or internalized without cleavage, the latter in a pathway that both produces amyloid beta-protein and also targets some molecules to the lysosomal compartment. Analysis of beta-amyloid precursor protein trafficking is confounded by the concomitant secretion and internalization of molecules from the cell surface. To address this issue, we developed an assay, based on the binding of radioiodinated monoclonal antibody, to measure the release and internalization of cell surface beta-amyloid precursor protein in transfected cells. With this approach, we showed that surface beta-amyloid precursor protein is either rapidly released or internalized, such that the duration at the cell surface is very short. Approximately 30% of cell surface beta-amyloid precursor protein molecules are released. Following internalization, a fraction of molecules are recycled while the majority of molecules are rapidly sorted to the lysosomal compartment for degradation When the C terminus of beta-amyloid precursor protein is deleted, secretion is increased by approximately 2.5-fold as compared to wild-type molecules. There is concomitant decrease in internalization in these mutant molecules as well as prolongation of the resident time on the cell surface. This observation is consistent with recent evidence that signals within the cytoplasmic domain mediate beta-amyloid precursor protein internalization.

Mantle cell lymphoma (formerly known as intermediate lymphocytic lymphoma, diffuse centrocytic lymphoma, or diffuse small cleaved lymphoma) is one of the small cell non-Hodgkin lymphoma entities that is clinically more aggressive than small lymphocytic lymphoma, and needs to be separated from it. Mantle cell lymphoma is strongly associated with the t(11;14) chromosomal translocation that rearranges the bcl-1 oncogene (PRAD-1 gene) and immunoglobulin heavy chain gene. In this study, we developed a nested polymerase chain reaction system to evaluate the t(11;14) translocation. The study material consisted of 10 mantle cell lymphomas fulfilling the criteria suggested by other authors (P. M. Banks et al. Surg Pathol 16:637, 1992). A novel nested polymerase chain reaction system was used to evaluate the bcl-1 breaks in the major translocation cluster using two successive polymerase chain reaction amplifications. This reaction yielded a background-free single product of the size of 200 to 300 base pairs in four of 10 mantle cell lymphomas. The identity of the product from the nested polymerase chain reaction was confirmed by Southern blotting followed by hybridization with a specific probe. The amplification products were also evaluated by Sst-I, Alu-I, Dde-I, and Ita-I restriction enzymes and showed different patterns of digestion reflecting individual differences between the MTC/ IgH junctions. A selection of other low-grade lymphomas, including lymphocytic, follicular, and mucosa-associated lymphoid tissue lymphoma, and hairy cell leukemia and 29 hyperplastic lymph nodes were negative. This nested polymerase chain reaction system for the t(11;14) translocation involving major translocation cluster offers a convenient specific identification for mantle cell lymphoma. However, this test has a limited diagnostic power because only about half of the mantle cell lymphomas show the bcl-1 breaks in the major translocation cluster. The test performs well in formaldehyde-fixed and paraffin-embedded material, allowing the study of large numbers of retrospective cases of mantle cell lymphomas.

Five cases of clinically aggressive, keratin-positive malignant lymphomas of B-cell type with unusual immunophenotypes were studied. All cases were extranodal: two from the stomach, one from soft tissue, one from the skin, and one from the spleen. These tumors were undifferentiated large-cell neoplasms that showed reactivity for low-molecular-weight keratin 8, but they were negative for keratin 19; three cases were also positive for epithelial membrane antigen. The immunohistochemical diagnosis was complicated by the fact that two of these cases lacked reactivity for leukocyte common antigen and three were CD20 negative. These findings simulated the immunophenotype of a carcinoma and led to an initial misdiagnosis of carcinoma. Although only two cases showed immunohistochemical evidence of B-cell lineage (CD20+), all five cases were documented as B-cell lymphomas on the basis of the clonal immunoglobulin heavychain gene rearrangement, as demonstrated by polymerase chain reaction (PCR) in all the cases and by Southern blot hybridization in three cases; all cases were negative for T-cell markers, and three cases showed germline configuration for T-cell receptor beta-chain. One case was strongly CD30 positive and represented large-cell anaplastic lymphoma of B-cell type. Our results show that some B-cell lymphomas can have unusual and confusing immunophenotypes, including keratin positivity and leukocyte antigen negativity. Use of PCR-based molecular genetic demonstration of clonal immunoglobulin heavychain gene rearrangement is helpful in establishing the correct diagnosis in such cases.

Conventional cytogenetic data and fluorescence in situ hybridization (FISH) interphase cytogenetic studies have shown that trisomy 12 is found in many cases of B-cell chronic lymphocytic leukemia (B-CLL). Several reports indicate that +12 is an acquired numerical cytogenetic abnormality, and may be associated with a worse prognosis or more extensive disease. Wright-Giemsa-stained blood or bone marrow smears obtained after initial diagnosis, and subsequent lymph node cells, bone marrow aspirate smears, or effusions were retrospectively studied from five patients whose disease underwent morphologic transformation from typical B-CLL to a high grade lymphoproliferative disease (Richter's syndrome). Using an alpha-satellite DNA probe to the centromere of chromosome 12, trisomy 12 was found in a proportion of cells from all five specimens with high grade lymphoproliferative disease, but in only one of five samples collected before transformation. These data suggest that +12 is an acquired cytogenetic abnormality in CLL and has a high frequency in Richter's syndrome. Because only a subpopulation of the neoplastic cells contain an extra copy of chromosome 12, it is unlikely that this numerical abnormality plays a direct role in transformation to high grade lymphoproliferative disease.

The cytogenetics of Hodgkin's disease (HD) is poorly understood. However, a t(2;5) is a common finding in CD30+ anaplastic large cell lymphoma (ALCL), a neoplasm thought by some to be closely related to HD. Recently, the t(2;5) has been cloned and found to represent fusion of the NPM gene with the ALK gene. Using Southern blot hybridization, one group has reported finding rearrangements of NPM in a proportion of cases of both ALCL and HD. In the current study, we used a highly sensitive reverse transcriptase-polymerase chain reaction methodology to analyze 34 cases of HD for the t(2;5). We were unable to find polymerase chain reaction evidence for the t(2;5) in any of the cases of HD, a result significantly different from our previous study of CD30+ non-Hodgkin's lymphomas (P < .02) including ALCL (P < .04), using identical methods. Our results do not support the hypothesis that the t(2;5) represents a common chromosomal abnormality for both HD and ALCL.

Human blood polymorphonuclear (PMN) leucocytes and human leucocytes of the HL-60 line, which were induced to differentiate by 1,25-dihydroxyvitamin D3, express stereospecific receptors for the potent chemotactic mediator, leukotriene B4 (LTB4), that is derived by 5-lipoxygenation from arachidonic acid. Monoclonal antibodies to LTB4 receptors (LTB4-R) were generated by immunizing BALB/c mice with partially purified PMN leucocyte membrane proteins, and fusing their splenocytes with P3X63Ag8 mouse myeloma cells. Hybridoma supernatants were screened initially by binding to PMN leucocyte LTB4-R protein, which had been affinity cross-linked with aminopropylamide (APA)-LTB4 and immobilized in plastic wells through attachment of the linked APA-LTB4 to adherent Fab of monoclonal anti-LTB4. Of the three clones producing antibodies which bound to LTB4-R, 0.5 mg/ml of one IgG3k antibody, termed E2, precipitated over 90% of the [3H]LTB4-binding activity of solubilized PMN leucocyte membrane proteins. E2 also bound to a radiolabelled protein of 70,000-80,000 MW from 125I-labelled PMN leucocyte membranes [35S]-labelled HL-60 cell membranes, and PMN leucocyte membranes affinity-labelled with [3H]APA-LTB4, that was identical in size to the LTB4-R precipitated by the rabbit IgG anti-idiotypic antibodies. E2 did not bind to intact PMN leucocytes or modify the binding of [3H]LTB4 by PMN leucocytes. The binding of E2 to LTB4-R in purified membranes of PMN leucocytes was less than one-fourth of that observed for the anti-idiotypic antibodies, but increased substantially after solubilization of the LTB4-R. The E2 monoclonal antibody thus recognizes a partially latent substituent of LTB4-R, which does not contribute to combining site function.

The components of the polymorphonuclear leukocyte (PMNL) receptor for leukotriene B4 (LTB4) were examined by Sephacryl S-300 exclusion chromatography of PMNL membrane proteins, which were solubilized before and after the binding of [3H] LTB4. When the PMNL membranes were solubilized in 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS) and filtered on Sephacryl S-300 prior to addition of [3H] LTB4, the binding activity was associated with a 65 kD protein. In contrast, the radioactivity of [3H] LTB4 bound to PMNL membranes prior to solubilization was recovered predominantly with a 140 kD protein. When PMNL membranes had been pretreated with pertussis toxin, but not cholera toxin, before the addition of LTB4 and subsequent solubilization, radioactivity was recovered predominantly with the 65 kD protein. The addition of guanylylimidodiphosphate (GMP-PNP), a nonhydrolyzable derivative of guanosine triphosphate (GTP), to PMNL membrane receptors bearing [3H] LTB4 either prior to or after CHAPS solubilization reduced the yield of the 140 kD presumed LTB4 receptor protein-G protein complex. That the maximum specific binding of [35S] guanosine-5'-0-3-thiotriphosphate (GTP-gammaS) to LTB4-binding proteins in the Sephacryl S-300 effluent corresponded to the 140 kD protein supported the presence of a G protein in the LTB4 receptor complex.

The relatively frequent association of hematologic neoplasia and primary mediastinal germ cell tumors has been reported. Of these hematologic malignancies, nine were classified as malignant histiocytosis or acute monoblastic leukemia, and all occurred in males. We now report on a patient who was phenotypically female, with 46XY gonadal dysgenesis, and who developed a true histiocytic malignancy that presented as a large hepatic tumor and also involved the spleen, right kidney, and lymph nodes. Twenty-six months before the development of the histiocytic malignancy, an ovarian malignant teratoma with yolk sac elements was removed; the patient subsequently received chemotherapy. The neoplasm was composed of large pleomorphic cells and the histiocytic nature was established by cytologic, cytochemical, immunologic, and ultrastructural studies. In the course of her illness, the patient developed classic acute monoblastic leukemia 8 months after the diagnosis of histiocytic malignancy. Karyotypic analysis of the hepatic tumor, bone marrow, and blood showed 46XY gonadal dysgenesis. We believe that this is the first reported case of a phenotypically female patient who developed these two rare malignancies. It suggests that the association between germ cell tumors and histiocytic malignancy in genotypically male individuals may not be coincidental or secondary to therapy, but may be a phenomenon related to dysgenetic gonads in the presence of a Y chromosome.

Pretreatment of suspensions of human polymorphonuclear leucocytes (PMNL) with leukotriene B4 (LTB4) induces chemotactic deactivation, characterized by diminished expression of high-affinity LTB4 receptors and selectively decreased chemotactic responsiveness of the PMNL to LTB4. Rabbit anti-idiotypic antibodies (a-Id) to mouse monoclonal anti-LTB4, which bind to 60,000-80,000 molecular weight (MW) membrane protein of PMNL receptors for LTB4 in Western blots and block binding of [3H]LTB4 to high-affinity receptors of PMNL, detected a reduction in LTB4 receptor antigen during chemotactic deactivation. Loss of high-affinity receptors for LTB4 from the surface of PMNL deactivated by incubation with 10 nM LTB4 was significant after 1 min and after 20 min reached a mean maximum of 82% and 61%, respectively, as assessed by binding of [3H]LTB4 and a-Id. Inhibitors of PMNL proteases did not prevent the deactivation-induced decreases in surface receptors for LTB4. Disruption of deactivated PMNL and solubilization of membrane proteins failed to expose intracellular LTB4 receptors. Incubation of membranes isolated from PMNL with 100 nM LTB4 resulted in a loss of LTB4 receptors similar to that observed in intact PMNL. Changes in LTB4 receptor protein structure or membrane localization, rather than endocytosis or proteolysis, thus appear to explain the rapidly decreased expression of LTB4 receptors, which results from stimulus-specific deactivation.

A recent clinicopathologic study of a series of patients with monocytoid B-cell lymphoma (MBCL) indicated that there is a frequent association between MBCL and Sjögren's syndrome (SS) and raised the possibility of a relationship between these two disease entities. To further investigate the possible relationship of MBCL and SS, we studied pathologic and clinical characteristics of 13 patients with MBCL who had clinically documented SS. In all patients, the lymphoma had the characteristic morphologic features of MBCL, and immunologic and molecular hybridization studies confirmed the B-cell nature of the lymphoma. Twelve of the 13 patients were female, with a median age of 66 years at diagnosis. Eleven had localized disease and presented with either salivary gland or cervical lymph node enlargement; one patient presented with a breast mass, and another with generalized lymphadenopathy and hepatosplenomegaly. In five of 13 patients, the MBCL was associated with or progressed to large cell lymphoma. In two patients, there was bilateral involvement of the parotid gland; one had a synchronous high-grade lymphoma in both parotid glands. In two patients, bone marrow biopsies showed involvement by MBCL. Eleven patients are alive 2 to 55 months after the diagnosis of MBCL. One patient died with the disease 8 months after the initial diagnosis. Another patient died of an unrelated cause without evidence of disease 16 months after the diagnosis of MBCL. We conclude that there is a more than fortuitous association between MBCL and SS. This concept is consistent with previously reported observations of reactive monocytoid B cells in patients with benign lymphoepithelial lesions of salivary glands, which may result from selective homing of reactive monocytoid B lymphocytes to the benign lymphoepithelial lesions and their subsequent neoplastic transformation.

There is a significantly increased incidence of malignant lymphoma in patients with acquired immunodeficiency syndrome (AIDS). The lymphomas are usually of a high grade and of B-cell phenotype. While the frequent presence of reactive monocytoid B lymphocytes in patients with AIDS-related lymphadenopathy has recently been documented in several studies, to our knowledge, there are no reported cases of monocytoid B-cell lymphoma, the neoplastic counterpart of monocytoid B lymphocytes, in patients with AIDS. We now describe a human immunodeficiency virus (HIV)-positive patient with HIV-related lymphadenopathy in whom monocytoid B-cell lymphoma developed during the course of his disease. The morphologic and immunologic features of the lymphoma were characteristic of monocytoid B-cell lymphoma, and the involved lymph node exhibited a reversed CD4/CD8 ratio. Moreover, using the polymerase chain reaction, we were able to demonstrate HIV genome in DNA extracted from the lymph node tissue. To our knowledge, this is the first report of a case of monocytoid B-cell lymphoma occurring in an HIV-positive patient and in which we were able, by using a sensitive molecular biologic technique, to demonstrate HIV sequence in paraffin-embedded, fixed lymph node sections.

Plasmacytoid T-cell lymphoma (PTL) is a rare lymphoma with unique morphologic, immunologic, and clinical features. Thus far, only three cases have been reported, each terminating in myeloid leukemia. The macrophage/monocyte rather than T-cell origin of "plasmacytoid T-cells" in reactive lymph nodes has been suggested in the past, but there has been no extensive investigation to demonstrate whether the PTLs are also of this lineage. The authors now report on a patient with PTL who had a long history of clinically stable idiopathic myelofibrosis. Immunocytochemical staining of the neoplastic plasmacytoid cells, with a large panel of monoclonal antibodies used on fresh-frozen and paraffin-embedded tissue sections, showed that the neoplastic cells expressed several macrophage/monocyte-associated markers, i.e., CD31, CD36 (thrombospondin receptor), and CD68 (KP1). Other markers of the macrophage/monocyte lineage (e.g., CD11b, CD11c, CD16) were absent. The neoplastic cells lacked B-cell-associated antigens and lacked most T-cell-associated markers, with the exception of CD2 and CD4. These findings are in close agreement with those of previous studies on normal plasmacytoid T-cells and support the macrophage/monocytic origin of PTL. Molecular hybridization studies provided additional support for the nonlymphoid origin of the plasmacytoid cells by demonstrating the absence of T-cell-receptor beta-chain and immunoglobulin heavy-chain gene rearrangements in the neoplastic cells. The results of the authors' studies indicate that "plasmacytoid T-cell lymphoma" associated with a chronic myeloproliferative disorder is of macrophage/monocyte lineage.

This study is based on an analysis of the morphologic, clinical, and laboratory findings in 26 patients whose pretherapy lymph node biopsies showed some, but not all, of the diagnostic features of angioimmunoblastic lymphadenopathy with dysproteinemia (AILD). Partial or complete effacement of nodal architecture by a diffuse lymphoplasmacytic and immunoblastic proliferation was a constant histologic finding. In contrast to the findings in AILD, lymphocytic depletion and pronounced arborizing vascular proliferation were often lacking. Clinically, many of the patients had fever, sweats, weight loss, skin rashes, generalized lymphadenopathy, hepatosplenomegaly, and, in some cases, pulmonary infiltrates. Of the 26 patients, 23 had clinical and/or laboratory evidence of autoimmune disease or immune complex disease. In 12 patients (Group I--idiopathic), various autoantibodies or immune complexes were demonstrable, but these patients did not manifest a well-defined immunologic disease or syndrome. In 11 patients (Group II--secondary), the lymphadenopathy occurred secondary to a well-defined, clinically recognized immunologic disease. Three patients (Group III) had neither a well-defined autoimmune disease nor demonstrable autoantibodies, but two of them had a history of exposure to antibiotics. We suggest that patients whose lymph nodes have the morphologic features described here frequently have an autoimmune disorder, and that the pathogenesis of this clinicopathologic picture is probably related to a deficiency in suppressor T-cell function which results in an unopposed proliferation of B cells with autoantibody formation and polyclonal gammopathy. Our observations should stimulate clinicians to consider the possibility of an autoimmune pathogenesis for a lymphadenopathy in which a florid lymphoplasmacytic and immunoblastic proliferation similar to that observed in AILD is demonstrated, even though the sections may not meet all the histologic criteria reported for the diagnosis of AILD. Clinical and laboratory investigations necessary to confirm the presence of autoimmunity are indicated in these cases. Moreover, since there is evidence of genetic factors predisposing to autoimmune disease (17, 43), it would be important to investigate close relatives of patients whose lymph nodes showed the histologic changes described in this paper in prospective studies which include suppressor T-cell function, autoantibodies, HLA type of blood lymphocytes and chromosomal analysis. The median survival of the 23 patients with stigmata of autoimmune disease or immune complex disease was 36 months.(ABSTRACT TRUNCATED AT 400 WORDS)

Human polymorphonuclear (PMN) leucocytes bind synthetic [3H]-labelled leukotriene C4 ([3H]LTC4) with rapid saturation and reversibility of approximately 90%, by a 700-fold higher concentration of non-radioactive LTC4. [3H]LTC4 is recognized specifically by 10,778 +/- 6260 (mean +/- SD) sites per PMN leucocyte that exhibit a KD of 34.3 +/- 1.7 nM. The specificity of the LTC4 receptors is supported by the competitive inhibition of binding of [3H]LTC4 by LTC4, LTC4-sulphone, LTD4, and LTE4 with relative potencies of approximately 100:20:3:1. The four-fold higher level of specific binding of [3H]LTC4 by sonicates than by intact PMN leucocytes is attributable to intracellular receptors. Of the total number of receptors recovered in sonicates of PMN leucocytes, one-third are associated with membranes and the other two-thirds with lysosomal granules. The affinity of the membrane receptors for LTC4 is indistinguishable from that of receptors on intact PMN leucocytes, whereas the affinity of granule receptors is significantly higher. The characteristics of the receptors are consistent with a role in mediating uptake and metabolism of LTC4 by PMN leucocytes.

A patient with renal failure due to Goodpasture's syndrome was treated with vancomycin. After he had received 3 g of the drug, his white blood cell count fell to a level of 200/microliter. Bone marrow biopsy disclosed severe myeloid hypoplasia. The patient subsequently recovered fully from this episode of vancomycin-induced agranulocytosis, but he eventually died of other causes. Vancomycin-related leukopenia has been reported, but the severely depressed white blood cell count and myeloid hypoplasia observed in this patient have not previously been described. Vancomycin must be excluded as the cause of leukopenia in any patient who is receiving this drug.

Isolated human polymorphonuclear (PMN) leukocyte plasma membranes express high affinity (mean Kd = 0.12 nM) and low affinity (mean Kd = 50 nM) receptors for the chemotactic factor leukotriene B4 (5(S),12(R)-dihydroxy-eicosa-6,14 cis-8,10 trans-tetraenoic acid; LTB4) that are similar to those on intact PMN leukocytes. A portion of high affinity LTB4-R on PMN leukocyte membranes were converted to the low affinity state by GTP (mean +/- SE = 28.6 +/- 14.0%) and nonhydrolyzable GTP analogues, such as 5'-guanylylimidodiphosphate (GMP-PNP), in a concentration-dependent, nucleotide-specific, and reversible manner, without altering the intrinsic binding affinities of either class. [3H]GMP-PNP bound specifically to one class of receptors (mean Kd = 13 nM) on PMN leukocyte membranes. The interdependence of the LTB4-binding membrane protein and guanine nucleotide-binding protein was suggested by the capacity of LTB4 to enhance by a maximum of 150% the binding of [3H]GMP-PNP to PMN leukocyte membranes by increasing the number, but not altering the affinity, of receptors for GMP-PNP. Pertussis toxin, but not cholera toxin, reversed the enhancement of binding of [3H]GMP-PNP produced by LTB4. Guanine nucleotide-binding proteins and high affinity LTB4-R thus exhibit a mutual regulation that differs mechanistically from that of peptide chemotactic factor receptors on PMN leukocytes.

Rabbit anti-idiotypic IgG antibodies to the combining site of a mouse monoclonal IgG2b antibody to leukotriene B4 (LTB4) cross-reacted with human polymorphonuclear (PMN) leukocyte receptors for LTB4. Anti-idiotypic IgG and Fab both inhibited the binding of [3H]LTB4, but not [3H]N-formylmethionyl-leucylphenylalanine (fMLP), to PMN leukocytes with similar concentration-effect relationships, whereas neither nonimmune rabbit IgG nor Fab had any inhibitory activity. At a concentration of anti-idiotypic IgG that inhibited by 50% the binding of [3H] LTB4 to PMN leukocytes, the antibodies preferentially recognized high affinity receptors. Anti-idiotypic IgG and Fab inhibited PMN leukocyte chemotactic responses to LTB4, but not fMLP, with concentration-effect relationships resembling those characteristic of the inhibition of binding of [3H] LTB4, without altering the LTB4-induced release of beta-glucuronidase. Chemotaxis and increases in the cytoplasmic concentration of calcium equal in magnitude to those elicited by optimal concentrations of LTB4 were attained at respective concentrations of anti-idiotypic IgG equal to and 1/25 the level required for inhibition of binding of [3H]LTB4 by approximately 50%. Thus, the anti-idiotypic antibodies bound to PMN leukocyte receptors for LTB4 with a specificity, preference for high affinity sites, and capacity to alter PMN leukocyte functions that were similar to LTB4.

The classification of non-Hodgkin's lymphomas (NHLs) has been traditionally based on analysis of histologic sections and has been supplemented more recently by immunologic marker studies. It was the purpose of the present study to illustrate, side-by-side, sections and Romanowsky-stained imprints from the same surgical specimen from practically all categories of immunophenotyped NHLs, including rare and atypical variants that were difficult to classify from the histologic sections alone. Our results indicate that imprint cytology may reveal nuclear and cytoplasmic details not discernible in even the best tissue sections and that it may be selectively helpful in contributing to the classification of NHLs. Our results also show that the relative value of imprint cytology in the classification of malignant lymphomas varies greatly among categories. Specifically, we have found that imprints assist in three ways: the recognition of plasmacytoid features in small cell lymphocytic lymphomas, the recognition of plasmacytoid immunoblastic lymphoma, and the differentiation between NHLs which may be difficult to distinguish histologically. These include (1) small lymphocytic lymphoma versus lymphocytic lymphoma of intermediate differentiation, (2) true histiocytic malignancies versus large cell malignant lymphomas with abundant cytoplasm and/or phagocytosis, (3) anaplastic myeloma versus plasmacytoid immunoblastic lymphoma, (4) large noncleaved versus plasmacytoid immunoblastic lymphoma, (5) lymphoblastic lymphoma versus diffuse small cleaved cell lymphoma, and (6) lymphoblastic lymphoma versus small noncleaved cell lymphoma. Lymph node imprints are easy to prepare and readily interpretable by those experienced in the study of abnormal blood and bone marrow films. Their value as an ancillary methodology aimed at optimal accuracy in the classification of NHLs should be recognized.

The effects of leukotriene D4 on the intracellular pH of human myelocytes, derived from cultured HL-60 cells by dimethylsulfoxide-induced differentiation, were quantified with the fluorescent indicator 2',7'-bis-(2-carboxy-ethyl)-5,6-carboxyfluorescein. Leukotriene D4, but not C4 or E4, increased intracellular pH optimally by 3 min with a half-maximal effect at 1-2 nM. The increases in intracellular pH stimulated by leukotriene D4 were prevented by pretreatment of myelocytes with leukotriene D4 but not peptide chemotactic factors. Analogs of amiloride that inhibit selectively the Na+/H+ antiport also prevented the intracellular alkalinization induced by leukotriene D4. The rate of recovery of intracellular pH after an acid load with 30 mM sodium propionate was approximately 30% higher at each level of intracellular pH for myelocytes exposed to leukotriene D4 than for those challenged in buffer alone. The increase elicited by leukotriene D4 in the adherence of myelocytic leukocytes to surfaces thus is associated with an enhanced sensitivity of the Na+/H+ antiport to intracellular pH, that is, not coupled to an earlier rise in the cytosolic level of Ca+2.

The potent mediators generated by the 5- and 15-lipoxygenation of arachidonic acid have diverse effects on smooth muscles, blood vessels, leukocytes, epithelial cells and glands, and sensory neurons, which suggest possible roles in the initiation and regulation of physiological and biochemical events. The responses to leukotrienes and related mediators are attributable to binding by stereospecific cellular receptors and consequent activation of biochemical transductional sequences analogous to those characteristic of other receptor systems. The elevated concentrations of these mediators in lesional fluids and tissues of inflammatory bowel disease and other hypersensitivity and inflammatory states are, in some instances, clearly related to the time course of development of the disease process. Systematic application of specific inhibitors and antagonists that are becoming available will define more clearly the involvement of leukotrienes in health and disease and possibly lead to new therapeutic approaches.

Eight hematopathologists independently reviewed 56 consecutive cases of benign and malignant lymphoproliferative disorders (LPD) to determine: (1) the degree of interobserver agreement on the interpretation of immunologic findings on fresh-frozen sections alone and on that of the immunologic findings in conjunction with corresponding hematoxylin and eosin (H & E)-stained histologic sections; (2) whether prior knowledge of morphologic characteristics influences the interpretation of immunohistologic sections; (3) whether immunologic phenotype could be predicted reliably based solely on study of histologic sections; and (4) the significance of immunologic data as an aid in the interpretation of histologic sections. The study was carried out in three independent review sessions consisting of (1) review of immunohistologic sections only, (2) review of the same immunohistologic sections together with histologic sections, and (3) review of the histologic sections alone. A consensus diagnosis was defined as agreement of five or more pathologists on the final diagnosis and identification of the immunophenotype. When the authors compared the total number of major disagreements in the first review session with those in the second, the accuracy of the determination of immunophenotype in the second session was clearly superior (P less than 0.05). Similarly, the total number of major disagreements in the second review session was significantly lower than that in the third review session (P less than 0.001). When histologic diagnoses in the second session were compared with those in the third session, it became apparent that the immunologic data helped the pathologist to correct major misinterpretations in 14 cases (25%). This study is the first to demonstrate quantitatively that (1) knowledge of morphologic features influences and greatly enhances the accuracy of the interpretation of immunologic findings, (2) the immunophenotype of LPD cannot be predicted based on morphologic findings alone, and (3) immunologic findings improve the accuracy of interpretation of histologic findings in situations in which a diagnosis cannot be made from morphologic features only.

The distinctive characteristics of human polymorphonuclear (PMN) leukocyte receptors for leukotriene B4 (LTB4) have been elucidated by studies of binding of [3H]LTB4, the structure of protein constituents of the receptors isolated from plasma membranes, and the effects of antireceptor antibodies. A high-affinity class of 4400 receptors with a KD of 0.4 nM mediates chemotaxis and increased adherence of PMN leukocytes, whereas a low-affinity class of 270,000 receptors with a KD of 61 nM mediates the release of lysosomal enzymes and increases in oxidative metabolism. The low-affinity receptors are composed of a 60,000-dalton protein-binding unit. The high-affinity receptors are composed of the same binding unit in association with a 40,000-dalton guanine nucleotide-binding protein. That antireceptor antibodies as well as LTB4 distinguish the two classes of receptors with different functional consequences suggests the possibility of unique approaches to the regulation of leukocyte function at the receptor level.

The C6-sulfidopeptide leukotrienes C4 (LTC4) and D4 (LTD4) evoked increases in the cytosolic concentration of intracellular calcium ([Ca+2]i) in dimethylsulfoxide-differentiated HL-60 cells, as assessed by the fluorescence of quin-2. The increases in [Ca+2]i reached a peak within 15-90 s, attained 50% of the maximum level at 1.2 nM LTD4 and 60 nM LTC4, were greater in maximal magnitude for LTD4 than LTC4, and subsided in 5-7 min. Flow cytometric evaluation of the LTD4-induced increases in [Ca+2]i, reflected in increases in the fluorescence of intracellular indo-1, revealed that a mean of 77% of differentiated HL-60 cells responded, as contrasted with lesser increases in only 50% of undifferentiated HL-60 cells. The capacity of pretreatment of HL-60 cells with LTD4 to prevent subsequent responses of [Ca+2]i to LTC4 and LTD4, and the finding that the serine-borate inhibitor of conversion of LTC4 to LTD4 suppressed concurrently both LTC4-induced rises in [Ca+2]i and increases in adherence to Sephadex G-25 indicated that the responses of HL-60 cells to LTC4 required conversion to LTD4. That pertussis toxin and a chemical antagonist of LTD4 reduced the [Ca+2]i response suggested a dependence on LTD4 receptors. The LTD4-induced increases in [Ca+2]i were dependent on extracellular calcium and diminished by lanthanum, but not affected by nifedipine nor associated with changes in membrane potential, as measured with the fluorescent probe 3,3'-dipentyloxacarbocyanine. Thus, the increase in [Ca+2]i in HL-60 cells, which is coupled to an increase in adherence, appears to involve LTD4 receptor-specific and voltage-independent calcium channels in the plasma membrane.