Integrin α6 and EGFR signaling converge at mechanosensitive calpain 2.

Cells sense and respond to mechanical cues from the extracellular matrix (ECM) via integrins. ECM stiffness is known to enhance integrin clustering and response to epidermal growth factor (EGF), but we lack information on when or if these mechanosensitive growth factor receptors and integrins converge intracellularly. Towards closing this knowledge gap, we combined a biomaterial platform with transcriptomics, molecular biology, and functional assays to link integrin-mediated mechanosensing and epidermal growth factor receptor (EGFR) signaling. We found that high integrin α6 expression controlled breast cancer cell adhesion and motility on soft, laminin-coated substrates, and this mimicked the response of cells to EGF stimulation. The mechanisms that drove both mechanosensitive cell adhesion and motility converged on calpain 2, an intracellular protease important for talin cleavage and focal adhesion turnover. EGF stimulation enhanced adhesion and motility on soft substrates, but required integrin α6 and calpain 2 signaling. In sum, we identified a new role for integrin α6 mechanosensing in breast cancer, wherein cell adhesion to laminin on soft substrates mimicked EGF stimulation. We identified calpain 2, downstream of both integrin α6 engagement and EGFR phosphorylation, as a common intracellular signaling node, and implicate integrin α6 and calpain 2 as potential targets to inhibit the migration of cancer cells in stiff tumor environments.

Do ryanodine receptors regulate transmitter release at the neuromuscular junction of rat?

It has been suggested that calcium that is stored in nerve terminals can be released via activation of ryanodine receptors and this source of calcium could serve to modulate evoked transmitter release. Calcium influx via voltage dependent calcium channels could lead to calcium induced calcium release via ryanodine receptors in neuronal tissue. This additional source of calcium could contribute to the total calcium that is available for transmitter release or it could result in having a negative feedback action on calcium influx and transmitter release. We examined the effect of blocking and activating the ryanodine receptors on quantal transmitter release at the rat neuromuscular junction. Intracellular recording techniques were used to monitor end-plate potentials and miniature end-plate potentials. The data supports the view that intracellular calcium released via ryanodine receptors suppresses calcium influx leading to depressed quantal release.

Chemotherapy as an adjunct in the initial management of cerebellar medulloblastomas. A preliminary report.

Eight consecutive children with biopsy-proven cerebellar medulloblastoma were treated with a combination of whole neuraxis radiation and prolonged chemotherapy using vincristine and cyclophosphamide. There was no evidence of tumor recurrence in the follow-up period, which ranged from 16 months to 7 years and 8 months following diagnosis. Morbidity associated with this regimen has been infrequent and easily reversible.

Neuroblastoma.

Neuroblastoma originates in the adrenal medulla or anywhere in the body that sympathetic tissue normally is present. It may present with a variety of symptoms due to primary tumor, metastatic disease, or unusual signs and symptoms such as opsoclonus-myoclonus or severe diarrhea. Despite the fact that this neoplasm responds to a variety of therapeutic modalities, it remains one of the most frustrating and difficult childhood tumors to treat and cure.

Factor XI deficiency in an Ashkenazi Jewish child, causing severe postoperative hemorrhage.

Although inherited coagulation factor deficiencies with negative bleeding histories are rare, cases such as the one presented herein may not be diagnosed at the time of surgery and may experience severe hemostatic problems postoperatively. It may be prudent to obtain an activated partial thromboplastin time preoperatively for all Ashkenazi Jews, including those with a negative history for a hemostatic disorder, because of the high incidence of factor XI deficiency in their population. Surgeons and anesthesiologists should be aware of the existence of this and other uncommon hemostatic disorders and their treatment when faced with serious, apparently unexplained postoperative hemorrhage.

Protective effect of residual splenic tissue after subtotal splenectomy.

Studies in animals and clinical experience in man have demonstrated that splenectomy leads to increased susceptibility to infection with encapsulated bacteria. Splenic tissue has an excellent ability to regenerate, even when implanted into subcutaneous tissue or the abdominal cavity. These implants, however, do not protect against bacterial challenge despite the fact that a number of other functions can be restored. We therefore studied the ability of residual splenic tissue to protect against challenge following subtotal splenectomy in Sprague-Dawley rats. Subtotal splenectomy was performed on 48 animals in which approximately 75% of the spleen was removed and left with a branch of its normal blood supply; 48 animals underwent total splenectomy and 48 had sham operations. Six months after surgery the groups were challenged intravenously with type 25 pneumococci to determine the LD50 for each group. Animals that had undergone subtotal splenectomy were more resistant to pneumococcal challenge than were asplenic animals, but they were not as resistant as normal animals. In addition, there was marked delay in death in the animals with subtotal splenectomy as compared with asplenic animals. Thus residual splenic tissue after subtotal splenectomy appears to confer some degree of protection against pneumococcal challenge.

Placental echolucencies: does their presence influence outcome following genetic amniocentesis?

Women undergoing genetic amniocentesis procedures were evaluated for the presence of ultrasonographic echolucencies within the placenta. Non-calcified sonolucencies < 4 to 5 cm were classified as subchorionic hematomas (SH). Of the 1,000 pregnancies evaluated, 153 (15%) pregnancies manifested SH prior to amniocentesis (study group). The indications for referral were similar in the study and control groups. There were 13 (1.3%) losses: 3 and 10 in the study and control groups, respectively, with no statistical difference in fetal losses between the groups: RR 1.52 (95% confidence interval 0.56-4.14; p = 0.32). Placental sonolucencies < 4 to 5 cm in diameter appear to be incidental ultrasound findings not associated with increased fetal loss following genetic amniocentesis. Complications following invasive prenatal diagnosis cannot be attributed to the presence of these common ultrasound findings.

Heterotropic splenic autotransplantation in the prevention of Haemophilus influenza meningitis and fatal sepsis in Sprague-Dawley rats.

It has been suggested that autotransplantation of splenic tissue following trauma may result in splenic implanta that protect the human host from severe infection with encapsulated bacteria. To test this hypothesis, Sprague-Dawley rats underwent sham operation, splenectomy, or splenectomy followed by autotransplantation of splenic fragments into the peritoneal cavity. Three months later, they were inoculated intranasally with H. influenzae b. The incidence and severity of bacteremia and meningitis were determined subsequently in 15 randomly selected rats from each group. Splenosis did not appear to confer significant protection against bloodstream dissemination. However, significantly more (p = 0.005) asplenic rats (13/15) developed meningitis than did splenosed rats (6/15). None of the rats with normal splenic tissue developed CNS infection. Thus, the occurrence of meningitis was reduced in autotransplanted rats as compared to asplenic rats. Ten remaining rats from each group were followed for 3 wk after inoculation and the number of deaths was recorded. All sham-operated and autotransplanted rats survived, whereas 7 of 10 asplenic rats died (p = 0.003). These studies indicate that surgically created splenosis offers the potential for reducing the risk of life-threatening sepsis.

Gonadal failure following busulfan therapy in an adolescent girl.

A girl with Philadelphia chromosome-positive CML (Ph1-positive CML) was treated with busulfan from the age of 10 years 11 months to 16 years. Before treatment she had no evidence of pubertal development and no sexual development has occurred over the ensuing 5 years. Endocrine evaluation revealed that the child had ovarian failure. The pubescent female appears to be prone to develop gonadal failure with resultant lack of sexual development when treated with busulfan during this period in her life.

The effect of age and postsplenectomy interval on the susceptibility of the asplenic adult rat to pneumococcal challenge.

The response to intravenous challenge with pneumococcus was examined in asplenic and sham-operated adult Sprague-Dawley rats eighteen weeks following surgery. The LD50 was over 2,0000 fold greater in the sham-operated animals than in the asplenic animals. These results suggest that the age of an asplenic host, the length of time following splenectomy, and the presence of a normal immune system other than the asplenic state do not in themselves confer immunity.

Thalassemia screening in Baltimore.

An education and screening program for beta-thalassemia was offered to members of the Greek and Italian communities in the Baltimore area to allow for educated decisions regarding childbearing. Similar programs have been effective in decreasing the incidence of beta-thalassemia major in other countries.

67Ga scintigraphy in granulocytic sarcoma.

Several granulocytic sarcomas (chloromas) developed in a patient with acute myelogenous leukemia while in hematologic remission. A positive diagnosis of the symptomatic lesion was made by means of open biopsy examination. The other lesions, which were unsuspected, were detected with a 67Ga-citrate scan. Subsequent 67Ga-citrate scans indicated a favorable response to treatment. The incidence and significance of silent granulocytic sarcomas in patients in hematologic remission is not known. Documentation of such lesions might prove valuable for diagnosing extramedullary relapse or for delivering intensive local therapy.

Haemophilus influenzae b infection in rats: effect of splenectomy on bloodstream and meningeal invasion after intravenous and intranasal inoculations.

We investigated the effect of splenectomy on the susceptibility of rats to intravenous or intranasal inoculation of Haemophilus influenzae, type b. The 50% lethal dose for asplenic rats inoculated either by intravenous (i.v.) (10(4.7)) or intranasal (i.n.) (10(4.6)) injection was similar, but significantly lower than the 50% lethal dose value in sham-operated rats (10(8.6) i.v. and 10(9.0) i.n.). Mean survival time was significantly longer for asplenic rats inoculated i.n. (49.3 h) compared to asplenic rats inoculated i.v. (24.4h). Similarly, sham-operated rats inoculated i.n. survived significantly longer after i.n. challenge (mean survival time, 171.4 h) than after i.v. challenge (34.7 h). Bacteremia was detected in 100% of asplenic rats and in 80% of sham-operated rats. The geometric mean number of bacteria in the blood of asplenic rats (10(4.90) per ml) was significantly greater than in sham-operated rats (10(3.29) per ml). Meningitis was detected in 7 of 15 randomly sacrificed asplenic rats, whereas none of 15 sham-operated rats had evidence of meningeal invasion. Thus, the asplenic rat was more susceptible to experimentally induced H. influenzae bacteremia, meningitis, and fatal sepsis and offers a biologically relevant experimental model for investigating the role of the spleen in defense against infection with encapsulated bacteria.

Disseminated intravascular coagulation in childhood acute lymphocytic leukemia with poor prognostic features.

Three children with ALL having poor prognostic features developed clinical and laboratory evidence of disseminated intravascular coagulation (DIC). Two developed a bleeding diathesis associated temporally with a rapid drop in blast cell counts during induction therapy with L-asparaginase, prednisone, and vincristine. One of these children died of massive cerebral hemorrhage. The third patient developed episodes of superficial thrombophlebitis associated with relapses and rising blast cell counts which responded to chemotherapy and treatment with heparin. The unusual association of ALL with DIC and the fact that all 3 patients had multiple poor prognostic signs have led us to monitor carefully the coagulation system and withhold L-asparaginase in patients with massive disease until the white cell count and organomegaly have responded to prednisone and vincristine. The more common association of DIC with non-lymphocytic leukemia and recent reports of the presence of the Ph' chromosome in children with leukemia morphologically resembling ALL suggest that chromosomal evaluation be done in selected leukemic patients.