Short-term PI3K Inhibition Prevents Breast Cancer in Preclinical Models

Antiestrogen medication is the only chemoprevention currently available for women at a high risk of developing breast cancer; however, antiestrogen therapy requires years to achieve efficacy and has adverse side effects. Therefore, it is important to develop an efficacious chemoprevention strategy that requires only a short course of treatment. PIK3CA is commonly activated in breast atypical hyperplasia, the known precancerous precursor of breast cancer. Targeting PI3K signaling in these precancerous lesions may offer a new strategy for chemoprevention. Here, we first established a mouse model that mimics the progression from precancerous lesions to breast cancer. Next, we demonstrated that a short-course prophylactic treatment with the clinically approved PI3K inhibitor alpelisib slowed early lesion expansion and prevented cancer formation in this model. Furthermore, we showed that alpelisib suppressed ex vivo expansion of patient-derived atypical hyperplasia. Together, these data indicate that the progression of precancerous breast lesions heavily depends on the PI3K signaling, and that prophylactic targeting of PI3K activity can prevent breast cancer.

PREVENTION RELEVANCE

PI3K protein is abnormally high in breast precancerous lesions. This preclinical study demonstrates that the FDA-approved anti-PI3K inhibitor alpelisib can prevent breast cancer and thus warrant future clinical trials in high-risk women.

Abstract P007: Short-term PI3K inhibition prevents breast cancer in preclinical models

Antiestrogen medication is the only chemoprevention currently available for women at a high risk of developing breast cancer; however, antiestrogen therapy requires years to achieve efficacy and has adverse side effects. Therefore, it is important to develop an efficacious chemoprevention strategy that requires only a short course of treatment. PIK3CA is commonly activated in breast atypical hyperplasia, the known precancerous precursor of breast cancer. Targeting PI3K signaling in these precancerous lesions may offer a new strategy for chemoprevention. Here, we first established a mouse model that mimics the progression from precancerous lesions to breast cancer. Next, we demonstrated that a short course prophylactic treatment with the clinically approved PI3K inhibitor alpelisib slowed early lesion expansion and prevented cancer formation in this model. Furthermore, we showed that alpelisib suppressed ex vivo expansion of patient-derived atypical hyperplasia. Together, these data indicate that the progression of breast precancerous lesions heavily depends on the PI3K signaling, and that prophylactic targeting of PI3K activity can prevent breast cancer.

Citation Format: Amy T. Ku, Adelaide Young, Ahmed A. Ibrahim, Wen Bu, Weiyu Jiang, Meng Lin, Laterrica C. Williams, Bryant McCue, George Miles, Chandandeep Nagi, Fariba Behbod, Yi Li. Short-term PI3K inhibition prevents breast cancer in preclinical models. [abstract]. In: Proceedings of the AACR Special Conference: Precision Prevention, Early Detection, and Interception of Cancer; 2022 Nov 17-19; Austin, TX. Philadelphia (PA): AACR; Can Prev Res 2023;16(1 Suppl): Abstract nr P007.

Abstract P6-17-15: Evaluating preclinical efficacy of anti-HER2 drug combinations using ER+/HER2 mutant models

Background

Until recently, HER2 gene amplification was the only mechanism of HER2 activation recognized. However, activating HER2 mutations have been noted in different cancer types. A trials of HER2 mutant breast cancer and the subsequent SUMMIT trial data have shown that monotherapy with the pan-HER drug neratinib as showed clinical efficacy, but with poor response durability. This study therefore investigates the preclinical efficacy of anti HER2 agents alone or in combination with endocrine therapy agents or in combination with CDK4/6 inhibitors using ER+/HER2 mutant cell lines and ex vivo HER2 mutant patient derived xenograft (PDX) model to define a more effective treatment approach.

Methods

ER+ breast cancer cell lines (T47D and MCF7) stably expressing HER2V777L, and ER+/HER2 mutant PDX model (HER2G778_P780 dup) were used to examine HER2 signaling and drug responses. Signaling downstream mutant HER2 was examined by immunoblot analysis. Effects of neratinib alone, neratinib + fulvestrant, and neratinib + abemaciclib on cell growth were examined in ER+/HER2 mutant cell lines and in an ex vivo HER2G778_P780 dup.

Results

We found that MCF7/T47D cells expressing HER2V777L and HER2G778_P780 dup PDX tumors showed strongly activated autophosphorylation of HER2 and increased expression of CDK4, CDK6, phospho-Rb, and cyclin D1 as compared to MCF7/T47D cells expressing HER2WT or ER+/non-HER2mut PDX modes, suggesting that HER2 mutations preferentially depend on CDK4/6 signaling for cell growth. Additionally, we showed that activating MCF7 HER2 V777L cause resistance to endocrine therapy treatment (fulvestrant IC50 >5μM). Further, we show that neratinib alone is effective at higher concentrations (IC50 < 2μM) in MCF7/HER2 V777L cells. We also demonstrate that abemaciclib alone exhibited moderate activity against MCF7 HER2 V777L cells (IC50 < 0.4μM) and additional activity in combination with neratinib (IC50 < 0.06μM) was seen. Moreover, ex vivo HER2 G778_P780 dup cells are relatively resistant to fulvestrant alone (IC50 < 0.2μM), neratinib alone (IC50 < 0.006μM), abemaciclib alone (IC50 < 0.04μM), and neratinib in combination with abemaciclib (IC50 < 0.005μM), suggesting that patients harboring ER+/HER2-mutant tumors may benefit from neratinib in combination with abemaciclib.

Conclusion

These preclinical data suggest that neratinib monotherapy may not be effective to treat ER+/HER2 mutant patients and we propose that simultaneous targeting of both HER2 and the CDK4/6 axis will be required for effective treatment of ER+ breast cancers harboring HER2 activating mutations.

Citation Format: Kavuri SM, Devarakonda V, Williams LC, Seker S, Lei JT, Singh P, Han A, Anurag M, Holloway KR, Welm AL, Ellis MJ. Evaluating preclinical efficacy of anti-HER2 drug combinations using ER+/HER2 mutant models [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-17-15.

Chromosome microarray analysis in a clinical environment: new perspective and new challenge

The analysis of the human genome has largely been undertaken in a research environment, but recent developments in technology and associated workflow have allowed diagnostic laboratories to interrogate DNA at significantly improved levels of resolution. Principally, whole genome-based analysis of copy number changes using microarrays has led to this method replacing conventional karyotyping as a routine diagnostic workhorse. The resolution offered by microarrays is an improvement of at least an order of magnitude compared to karyotyping, but it comes at a cost in terms of the time spent in data interpretation. Overall, however, the die has been cast and cytogeneticists need to become familiar with the tools use by molecular geneticists and bioinformaticists. The following review provides a brief background to array technology, but uses a series of case studies to illustrate the usefulness and challenges of interpreting array data.

Update on systemic glucocorticosteroids in dermatology

Although dermatology now has the most extensive group of systemic medications available for the treatment of skin diseases at any time, GCSs remain the most important agents for managing inflammatory disorders. It is important that the dermatologist have a broad knowledge of guidelines for clinical use, pharmacology, and adverse effects of these drugs. Acute and chronic side reactions should be well recognized. An understanding of the HPA axis and reasons for administering GCSs in different ways is of great value. A good medical history should be taken on any patient treated with GCSs, including knowledge of conditions that would make GCSs inadvisable and other concomitant systemic medications that might produce drug interactions. During the course of therapy, physical examination should include all systems pertinent to side effects caused by these agents, including frequent evaluations of weight and blood pressure. Blood chemistries should be performed on a regular basis, including glucose, electrolytes, and serum lipids. Osteoporosis is one of the most significant adverse affects to be evaluated, with bone mineral density studies recommended on an annual basis for persons continuing on GCS therapy. If hip or other joint pain develops, MR imaging is the most specific and sensitive radiologic examination for evaluating the possibility of osteonecrosis. An ophthalmology examination should be performed every 6 to 12 months to detect early cataract or glaucoma development. Any early signs of infection should be evaluated by appropriate smears, wet preparations, and cultures. Many other studies, including gastrointestinal and pulmonary examinations, may be dictated by specific acute situations. It is important to begin early prevention of the bone loss that occurs with GCS-induced osteoporosis. The 1996 guidelines of the American College of Rheumatology, including adequate calcium and vitamin D intake, should be followed. Hormonal replacement, a bisphosphonate, calcitonin, or a thiazide diuretic may be indicated. Restriction of sodium in the diet is important, as well as adequate potassium intake. The diet should be low in saturated fat and calories and should be high in vegetable protein. Because osteoporosis is so prevalent with GCSs, keeping the patient as active as possible with mild-to-moderate exercise is important. Whenever possible, exposure to persons with infectious processes should be avoided, and proper treatment should be instituted at the initial signs of systemic or cutaneous infection. Oral doses of GCSs are best taken with food to prevent gastrointestinal irritation, and agents for gastric acidity occasionally may be indicated. Significant trauma should be prevented, as should severe exposure to the sun. Many situations may call for consultation with other medical or surgical subspecialists. The patient must be aware of the importance of regular physician evaluations and reporting of any adverse effects while on long-term GCSs. A good relationship and understanding between the patient and physician are vital in minimizing potential problems from these agents. If the dermatologist maintains the proper guidelines of care, patients on GCSs have the highest benefits and lowest risks possible.

Further evidence of the absence of measles virus genome sequence in full thickness intestinal specimens from patients with Crohn's disease

Specimens of macroscopically inflamed and normal intestine along with mesenteric lymph nodes were obtained at resection from patients with Crohn's disease. The samples were systematically examined by RT-PCR-nested PCR targeting N, M and H gene regions of the measles virus genome. None of the samples examined gave any evidence of the persistence of measles virus in the intestine of Crohn's disease patients. The study supports previous findings produced by this laboratory and others using highly sensitive measles virus specific PCR diagnostic technology.

Zebrafish: bridging the gap between development and disease

The zebrafish has been the model of choice amongst developmental biologists for many years. This small freshwater species offers many advantages to the study of organ and tissue development that are not provided by other model systems. Against this background, modern molecular genetic approaches are being applied to expand the physical and genetic mapping of the zebrafish genome. These approaches complement the large-scale mutagenic screens that have led to the isolation of mutant phenotypes. Some of the phenotypes have been found to resemble human disease states, while mapping and sequencing data have revealed zebrafish genes with significant homology to human disease-causing genes. It is the realization that the zebrafish offers an amenable system for understanding disease, as opposed to development, that underpins this review. The adventitious identification of disease phenotypes amongst zebrafish mutants and the important area of deliberate disease modelling using transgenesis and gene targeting should lead to a better application of the zebrafish as a vertebrate model of human diseases.

Systemic glucocorticosteroid therapy in dermatology

Glucocorticosteroids (GCS) have been frequently used for a number of dermatologic conditions since the early 1950s. These drugs continue to be very efficacious, yet there are serious side effects associated with their long-term use. Significant complications produced by GCS can be minimized by proper management and precautions. All health care professionals should be aware of these strategies and nursing personnel can play a vital role in helping patients adhere to the guidelines of preventing adverse events.

Null alleles at the Huntington disease locus: implications for diagnostics and CAG repeat instability

PCR amplification of the CAG repeat in exon 1 of the IT15 gene is routinely undertaken to confirm a clinical diagnosis of Huntington disease (HD) and to provide predictive testing for at-risk relatives of affected individuals. Our studies have detected null alleles on the chromosome carrying the expanded repeat in three of 91 apparently unrelated HD families. Sequence analysis of these alleles has revealed the same mutation event, leading to the juxtaposition of uninterrupted CAG and CCG repeats. These data suggest that a mutation-prone region exists in the IT15 gene bounded by the CAG and CCG repeats and that caution should be exercised in designing primers that anneal to the region bounded by these repeats. Two of the HD families segregated null alleles with expanded uninterrupted CAG repeats at the lower end of the zone of reduced penetrance. The expanded repeats are meiotically unstable in these families, although this instability is within a small range of repeat lengths. The haplotypes of the disease-causing chromosomes in these two families differ, only one of which is similar to that reported previously as being specific for new HD mutations. Finally, no apparent mitotic instability of the uninterrupted CAG repeat was observed in the brain of one of the HD individuals.

Comparative semi-automated analysis of (CAG) repeats in the Huntington disease gene: use of internal standards

Huntington disease (HD) belongs to the group of neurodegenerative disorders characterized by unstable expanded trinucleotide repeats. In the case of HD, the expansion of a CAG repeat occurs in the IT15 gene. The detection of the expanded CAG repeats has usually involved the electrophoretic separation of polymerase chain reaction (PCR) amplification products using conventional agarose and acrylamide gel electrophoresis. We have undertaken the comparative analysis of sizing CAG repeats of the IT15 gene using radioactive and fluorescent PCR amplification, and the subsequent separation of these products by slab gel and capillary electrophoresis. The assays have been performed on both cloned and sequenced CAG repeats, as well as genomic DNA from HD patients with a wide range of repeat lengths. The mobility of the CAG repeat amplification products of the IT15 gene is greater using capillary electrophoresis compared to slab gel electrophoresis. The analysis of 40 DNA samples from HD patients indicates that the mobility difference increases with the length of the repeat. However, we have devised an allele ladder for sizing the CAG repeats. This ladder provides a mandatory internal calibration system for diagnostic purposes and enables the confident use of either capillary or slab gel electrophoresis for sizing HD alleles.

Sequence of the gene encoding a highly thermostable neutral proteinase from Bacillus sp. strain EA1: expression in Escherichia coli and characterisation

The gene for a highly thermostable neutral proteinase (Npr) was isolated from Bacillus sp. strain EA1 by the polymerase chain reaction using consensus primers based on the sequences of npr genes from related species. The gene was sequenced and shown to be closely related to a neutral proteinase gene from Bacillus caldolyticus strain YP-T; the mature form of the enzyme differing by only a single amino acid. Enzyme samples were prepared from both the native organisms and also from recombinant Escherichia coli expressing the two npr genes. The proteinase from strain EA1 was shown to be significantly more thermostable than that from B. caldolyticus and that this difference is the result of a single amino acid substitution which is situated proximal to a region of the enzyme known to be crucial to conferring thermal stability. The phylogenetic relationship of EA1 to other Bacilli is also described.

Sequence and expression of a xylanase gene from the hyperthermophile Thermotoga sp. strain FjSS3-B.1 and characterization of the recombinant enzyme and its activity on kraft pulp

A gene expressing xylanase activity was isolated from a genomic library of Thermotoga sp. strain FjSS3-B.1. The sequence of the gene shows that it encodes a single domain, family 10 xylanase. The recombinant enzyme has extremely high thermal stability, activity over a relatively broad pH range, and activity on Pinus radiata kraft pulp.

A single emm gene-specific oligonucleotide probe does not recognise all members of the Streptococcus pyogenes M type 1

Serological typing of the streptococcal M protein has recently been challenged by a number of unique molecular methodologies based on oligonucleotide recognition of allelic variations within the M protein (emm) gene. In these methods, stringent hybridization of an oligonucleotide probe to a polymerase chain reaction amplified emm gene is used as confirmation of specific M type identity. A sample of 17 isolates from 7 previously defined distinct genotypes were tested using a single M1 oligonucleotide probe. Isolates from only three of the genotypes hybridized with the probe. The results demonstrate that a single emm-specific oligonucleotide probe can not identify all members of M type 1, as defined by conventional serotyping using polyclonal antisera.

Secondary structure model for an unusual SSU rRNA from the extremely thermophilic bacterium strain AZ3 B.1

The SSU rRNA gene of the extremely thermophilic bacterium strain AZ3 B.1, encodes an rRNA containing four large inserts. A secondary structure model has been constructed which predicts that the inserts form large stem loop structures with a common sequence motif at the base of the helices. To date, these structures have only been detected in related, thermophilic organisms.

Phylogeny and lipid composition of Thermonema lapsum, a thermophilic gliding bacterium

1,490 nucleotides of the 16S rRNA gene of a Gram-negative, thermophilic and gliding bacterium, Thermonema lapsum, have been sequenced. Phylogenetic analysis indicates that T. lapsum is related to cytophaga-flavobacteria-bacteroides (CFB) and is confirmed by the identification signature nucleotides that define this group. Further phylogenetic analysis indicates that T. lapsum forms the deepest branch in the CFB group; this observation was confirmed by the identification of unique nucleotide and nucleotide pairs which separate T. lapsum from all other members of this group. The phospholipid fatty acid (PLFA) profile also confirmed that T. lapsum is related to the cytophaga-flavobacteria-bacteroides group and also to selected members of the genus Flexibacter; the PLFA profile is unique to T. lapsum.

Atrioventricular valve competence after takedown to improve exposure during ventricular septal defect repair

Although the atrioventricular valve and its attachments can sometimes obscure the superior margin of a ventricular septal defect, concern for valvular competence has made surgeons hesitant to take down the atrioventricular valve. Over a 10-year period, the right atrioventricular valve was taken down to improve exposure for ventricular septal defect repair in 40 patients at our institution, and follow-up echocardiographic studies to determine the degree of valvular regurgitation were available in 32. On the basis of the area of the color flow jet, valvular regurgitation was graded as none in 22 and trivial in 10. Heart block did not develop in any patient, and there were no deaths. Takedown and resuspension of the atrioventricular valve is a safe and effective technique that improves exposure for ventricular septal defect repair and does not adversely affect valve competence.

Phylogeny of twenty Thermus isolates constructed from 16S rRNA gene sequence data

The sequences of the 16S rRNA genes of 20 Thermus isolates were determined to a high fidelity by using automated DNA sequencing and fluorescent-dye-labelled primers. The strains tested included members of the three validly named Thermus species and representatives of major taxonomic clusters defined previously for this genus. The parsimony method was used to reconstruct the phylogeny of the strains from the aligned sequences, and a bootstrap analysis revealed a number of well-supported clades. Our results are not consistent with groupings inferred from numerical taxonomy data but support the conjecture that the genus Thermus contains more species than the three currently recognized species.

Polymerase chain reaction in detection of CMV DNA in renal allograft recipients

This study investigates the use of polymerase chain reaction (PCR) in comparison with viral culture and serology for monitoring of cytomegalovirus (CMV) infection in 21 consecutive renal allograft recipients treated with a quadruple immunosuppression protocol. In addition, an attempt is made to explore the significance of quantitation of CMV signals obtained from peripheral blood leucocytes. CMV infection developed in 16 patients with seven of these patients having organ involvement. All of these 16 patients had a fourfold rise in antibody titres as well as positive identification of CMV DNA in peripheral blood leucocytes by PCR. Blood viral cultures were negative in two of these patients. All five patients who remained PCR negative also remained culture negative with no antibody change. PCR detected CMV infection on average 15 days and 20 days earlier than viral culture and serology respectively. All except one of the patients with CMV organ involvement had an initial peak of CMV DNA followed by prolonged carriage of detectable CMV. The majority of patients with fever only or asymptomatic CMV infection had a transient peak of CMV DNA. A high incidence of CMV disease with organ involvement occurred in seronegative recipients of kidneys from seropositive donors (3/5) and in seropositive recipients of kidneys from seronegative donors (3/7). OKT3 was associated with a higher incidence of CMV organ involvement compared to Antilymphocytic globulin (3/5 v 4/16) but there was a higher incidence of CMV mismatched patients in the OKT3 treated group.(ABSTRACT TRUNCATED AT 250 WORDS)

celB, a gene coding for a bifunctional cellulase from the extreme thermophile "Caldocellum saccharolyticum"

"Caldocellum saccharolyticum" is an obligatory anaerobic thermophilic bacterium. A gene from this organism, designated celB, has been cloned in Escherichia coli as part of a bacteriophage lambda gene library. This gene produces a thermostable cellulase that shows both endoglucanase and exoglucanase activities on test substrates and is able to degrade crystalline cellulose to glucose. The sequence of celB has homology with both exo- and endoglucanases described by others. It appears to have a central domain without enzymatic activity which is joined to the enzymatic domains by runs of amino acids rich in proline and threonine (PT boxes). Deletion analysis shows that the exoglucanase activity is located in the amino-terminal domain of the enzyme and that endoglucanase activity is located in the carboxy-terminal domain. There are internal transcriptional and translational start sites within the gene. The intact gene has been cloned into a temperature-inducible expression vector, pJLA602, and overexpressed in E. coli. Polyacrylamide gel electrophoresis showed that celB produced a protein with a molecular weight of 118,000 to 120,000. A number of smaller proteins with activity against carboxymethyl cellulose and 4-methyl umbelliferyl-beta-D-cellobioside were also produced. These are believed to be the result of alternative translational start sites and/or proteolytic degradation products of the translated gene product.

Pulmonary artery banding: analysis of a 25-year experience

A 25-year experience (May 1962 through April 1987) with pulmonary artery banding in 183 patients was reviewed and analyzed. Pulmonary artery banding was performed in a heterogeneous group of patients aged two days to 60 months (median, 10 weeks; mean, 21.8 weeks) and weighing 1.4 to 13.8 kg (mean, 4.2 kg). Diagnosis was ventricular septal defect in 76 (41.5%) and atrioventricular communis in 41 (22.4%). Pulmonary artery banding was also used in patients with d-transposition of the great vessels with ventricular septal defect, double-outlet right ventricle, univentricular heart, tricuspid atresia, and truncus arteriosus. Early death occurred in 39 of 175 patients who underwent pulmonary artery banding at Ochsner Foundation Hospital (22.3%). Definitive operation has been performed in 37 of the patients who underwent pulmonary artery banding since 1979 with excellent outcome in 32 (86.5%). Pulmonary artery banding is a useful palliative procedure for a diverse group of patients with congenital cardiac anomalies and unrestricted pulmonary blood flow. With improved results of primary repair of intracardiac anomalies in small infants, however, pulmonary artery banding should be reserved for severely ill patients with complex lesions not amenable to early definitive correction. Currently, pulmonary artery banding is indicated in patients with excessive pulmonary blood flow and single ventricle or tricuspid atresia. Pulmonary artery banding is also appropriate in certain patients with atrioventricular communis and in patients with muscular or multiple ventricular septal defects. Pulmonary artery banding is an option in patients with ventricular septal defect and coarctation of the aorta.

Antibodies against platelet glycosphingolipids: detection in serum by quantitative HPTLC-autoradiography and association with autoimmune and alloimmune processes

In order to assess the importance of glycosphingolipids (GSL) in the immunology of the platelet, serum antibody binding to immobilized, purified platelet GSLs have been quantitatively measured via high-performance thin-layer chromatography (HPTLC), 125I-radio-immunolabeling, autoradiography, and densitometry. Thirteen neutral GSL bands were detected at Rf.03 through .64 (CHCl3-CH3OH-H2O, 65:25:4) after extraction and chromatography (DEAE-Sephadex and Bio-sil A). Both IgM and IgG serum antibody binding was determined for 50 subjects from four groups: normal blood donors (NBD, n = 18); leukemia patients with nonimmune thrombocytopenia (NIT, n = 10); patients with systemic lupus erythematosus (SLE, n = 10); and patients with chronic autoimmune thrombocytopenia (CATP, n = 12). The ABO typing of these 50 subjects also allowed correlation of serum antibody binding with A blood group antigen expression. These studies reveal: (1) anti-GSL binding at band .06 is associated with blood group A alloantigen expression for both IgG and IgM (P less than .0001) antibodies; (2) binding at bands .17, .27, and/or .46 is associated with general autoimmunity (SLE and CATP) for IgM (P less than .0001); (3) binding at bands .35 and/or .38 is associated with platelet-specific autoimmunity (CATP) for IgG and/or IgM (P less than .005); and (4) binding at bands .03, .20, .23, and/or .43 is frequently observed for sera from all groups. The platelet specificity of bands .35 and .38 was confirmed by comparative studies with human intestinal smooth muscle GSLs. Quantitation of the intensity of CATP-associated anti-GSL binding (86 +/- 88 mm2) is comparable to anti-A alloantigen binding (57 +/- 52 mm2). Two of the GSL bands associated with SLE and CATP appear to be the long-chain fatty-acyl forms of globotriaosyl ceramide (.27) and globotetraosyl ceramide (.17), which are the Pk and P blood group antigens, respectively. These studies indicate that neutral GSLs may be important antigens in both autoimmune and alloimmune processes involving the blood platelet.

Creation of H-2 class I epitopes using synthetic peptides: recognition by alloreactive cytotoxic T lymphocytes

A major role that cytotoxic T lymphocytes (CTLs) play in the immune response is the specific destruction of viral-infected cells and tissue from foreign grafts. Class I molecules encoded within the major histocompatibility complex are the target structures for these CTLs. Recently, viral-restricted CTLs have been shown to recognize viral peptides in association with class I molecules, while several studies with cloned alloreactive CTLs have indicated that these T cells can recognize class I-derived peptides in association with class I molecules. Together, these observations suggest that peptide binding is an important function of class I molecules. In this paper, we show that the recognition of a particular class I molecule by a bulk population of alloreactive CTLs can be altered by incubating with it a peptide derived from another class I molecule. Specifically, we used the hybrid D/Ldm1 molecule as a target structure together with the peptide Ld61-85, and we have shown that their associative recognition by Ld-specific CTLs depends on sequence and configuration of the peptide and is specific for Ld using a cold-target inhibition assay. Our results are discussed in light of three possible models for the target structure(s) that can be recognized by alloreactive CTLs and in terms of the role peptides may play during allorecognition.

Milk alkali syndrome following over-the-counter antacid self-medication

Four patients with mild, asymptomatic chronic renal failure became severely hypercalcaemic while taking over-the-counter antacids with daily calcium loads of only 4-8 g. Renal impairment carries an increased liability to this syndrome. Persistent elevation of serum parathyroid hormone levels led to parathyroid exploration in two of the cases, and normal glands were found. In retrospect the hormone levels were appropriate to the degree of renal impairment. Over-the-counter antacid preparations should carry dosage warnings to avoid the possibility of hypercalcaemia.

Technique and experience with azygos patch modified Blalock-Taussig anastomosis for congenital cyanotic heart disease

Seventeen patients 1 day to 28 months old with congenital cyanotic heart disease underwent a modification of the Blalock-Taussig shunt. Eight were newborn infants weighing 2.6 to 4.8 kg. All infants had complex congenital heart defects that were not considered amenable to early correction. There were no early deaths and no shunt failures. Postoperative complications were restricted to prolonged intubation in 2 patients and a subcutaneous wound infection in a 14-day-old infant. Follow-up from 1 to 31 months revealed minimal cyanosis, stable hemoglobin levels, and good shunt murmurs, and there have been no upper extremity complications. There were 2 late deaths; 1 (the oldest patient) was related to medication, and the second resulted from small bowel necrosis. The concept of the azygos vein patch modified Blalock-Taussig shunt involves two factors: (1) mobilizing as much length as possible of the subclavian artery in spite of its distal small size to allow for a tension-free shunt to prevent tension on the anastomosis as growth occurs, and (2) enlarging the subclavian artery distal to the vertebral artery origin with an autologous azygos patch. During performance of a standard Blalock-Taussig shunt, a longitudinal incision is made through the pulmonary artery across the anastomosis into the upper subclavian artery. The appropriate length of harvested azygos vein is used as a patch angioplasty across the shunt. A tension-free shunt with a patulous distal portion is achieved. Pulmonary overcirculation is avoided by the limiting size of the proximal subclavian artery. Temporary occlusion of the shunt at operation resulted in an increased mean blood pressure from 6 to 18% in all infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Psychosocial problems in chronically ill children: physician concern, parent satisfaction, and the validity of medical records

This study concerns the psychosocial aspects of treatment for chronically ill children. The English-speaking parents of 44 children 5-13 years of age being seen at five specialty clinics at a large county hospital in Los Angeles, and their attending physicians, were the subjects in this study. The parents were interviewed concerning their expectations for the current visit, and the doctor-patient interaction was tape-recorded. Identical categories of information were abstracted from the tape recording and from a chart review of the patients' medical records. Although parents expected 76% of the psychosocial aspects of care to be covered by the doctor, only one fourth were actually discussed in the visit. These unfulfilled expectations were associated with lower satisfaction with medical care received (r = .47, p less than 0.01). Finally, while doctors recorded about 80% of discussions of symptoms and physical examinations in the patient's medical record, they recorded only 25% of discussion of psychosocial problems.

Plasma exchange in Goodpasture's syndrome

The clinical course and levels of anti-glomerular basement membrane (GBM) antibody were compared in 20 patients with Goodpasture's syndrome treated with plasma exchange and immunosuppression (8 patients), immunosuppression alone (4 patients) or no specific therapy (8 patients). There was a more rapid fall in the level of anti-GBM antibody and pulmonary hemorrhage was less protracted in the 8 patients treated with plasma exchange and immunosuppression. In this group, 1 patient who presented with severe renal failure showed a marked improvement of renal function and there was no progression of disease in the 4 with milder renal involvement. 2 of the 4 patients treated with immunosuppression alone, and only 2 of the 8 patients who received no specific therapy, maintained normal renal function. In the group which received no specific therapy, 1 of the 6 patients who progressed to renal failure had mild renal involvement initially. There was a significant correlation between the level of anti-GBM antibody and the severity of the morphological changes seen at renal biopsy but not between the level of anti-GBM antibody and the severity of lung hemorrhage. The course and outcome of the disease in those patients not treated, or treated with immunosuppression alone, was better than that described in early reports of this disease, while those patients with plasma exchange and immunosuppression fared even better. An adequately stratified controlled trial of immunosuppression and plasma exchange versus immunosuppression alone is in order.

The amino acid sequence of the beta subunit of allophycocyanin

The complete amino acid sequence of the beta subunit of Anabaena variabilis allophycocyanin is: H2N-Ala-Gln-Asp-Ala-Ile-Thr-Ala-Val-Ile-Asn-Ser-Ala-Asp-Val-Gln-Gly-Lys-Tyr-Leu-Asp-Thr-Ala-Ala-Leu-Glu-Lys-Leu-Lys-Ala-Tyr-Phe-Ser-Thr-Gly-Glu-Leu-Arg-Val-Arg-Ala-Ala-Thr-Thr-Ile-Ser-Ala-Asn-Ala-Ala-Ala-Ile-Val-Lys-Glu-Ala-Val-Ala-Lys-Ser-Leu-Leu-Tyr-Ser-Asp-Ile-Thr-Arg-Pro-Gly-Gly-Asn-Met-Tyr-Thr-Thr-Arg-Arg-Tyr-Ala-Ala-Cys-Ile-Arg-Asp-Leu-Asp-Tyr-Tyr-Leu-Arg-Tyr-Ala-Thr-Tyr-Ala-Met-Leu-Ala-Gly-Asp-Pro-Ser-Ile-Leu-Asp-Glu-Arg-Val-Leu-Asn-Gly-Leu-Lys-Glu-Thr-Tyr-Asn-Ser-Leu-Gly-Val-Pro-Val-Gly-Ala-Thr-Val-Gln-Ala-Ile-Gln-Ala-Ile-Lys-Glu-Val-Thr-Ala-Ser-Leu-Val-Gly-Ala-Asp-Ala-Gly-Lys-Glu-Met-Gly-Ile-Tyr-Leu-Asp-Tyr-Ile-Ser-Ser-Gly-Leu-Ser-COOH Phycocyanobilin is attached though a thioether linkage to cysteinyl residue 81, indicated by an asterisk. Comparison of this sequence with those of C-phycocyanins shows that there are 60 identities between corresponding subunits of these two biliproteins. Of the region between residues 79 and 120, 29 residues are identical in the beta subunits of allophycocyanin and phycocyanin. The character of all 10 charged residues in this region of the beta subunit sequences is completely conserved.

A histone-like protein (HTa) from Thermoplasma acidophilum. II. Complete amino acid sequence

The complete amino acid sequence of the DNA-binding histone-like protein (Hta) from Thermoplasma acidophilum has been established by sequence studies directly on the protein and on tryptic, chymotryptic, and thermolysin peptides derived from the protein. The sequence of the 89-residue form of HTa is: H2N-Val-Gly-Ile-Ser-Glu-Leu-Ser-Lys-Glu-Val-Ala-Lys-Lys-Ala-Asn-Thr-Thr-Gln-Lys -Val-Ala-Arg-Thr-Val-Ile-Lys-Ser-Phe-Leu-Asp-Glu-Ile-Val-Ser-Glu-Ala-Asn-Gly-Gl y-Gln-Lys-Ile-Asn-Leu-Ala-Gly-Phe-Gly-Ile-Phe-Glu-Arg-Arg-Thr-Gln-Gly-Pro-Arg-L ys-Ala-Arg-Asn-Pro-Gln-Thr-Lys-Lys-Val-Ile-Glu-Val-Pro-Ser-Lys-Lys-Lys-Phe-Val- Phe-Arg-Ala-Ser-Ser-Lys-Ile-Lys-Tyr-Gln-Gln-COOH The molecular weight calculated from the sequence is 9,934. Another form of HTa probably differs only by the presence of an additional residue (methionine) at the NH2 terminus (the calculated molecular weight of this form is 10,065). HTa resembles eukaryotic histones in several ways, including some sequence homology, HTa also shows sequence homology with the Escherichia coli DNA-binding proteins NS1 (or HU-1) and NS2 (or HU-2).

The effects of two different dosage regimens of sulphinpyrazone on platelet function ex vivo and blood chemistry in man

When sulphinpyrazone (either 200 mg q.d.s. for 7 days or 400 mg b.d.s. for 5 days) was administered to human volunteers, inhibition of platelet function was observed ex vivo. The inhibitory effect was measured by the increase in the concentration of sodium arachidonate required to cause platelet aggregation and a decrease in the biosynthesis by the platelets of malondialdehyde from added sodium arachidonate. ADP-induced primary platelet aggregation was statistically significantly inhibited only on 1 day of the two studies. The inhibitory effect did not correlate with the plasma concentrations of unchanged sulphinpyrazone nor with its sulphone metabolite but correlated with the plasma concentration of the thioether metabolite (r = 0.577, p less than 0.001). Platelet count, plasma fibrinogen, beta-thromboglobulin, urea and creatinine concentrations were not changed by the drug but there was a clinically insignificant increase in bleeding time in all but one subject.

Platelet protection and heparin sparing with prostacyclin during regular dialysis therapy

When prostacyclin (5 ng kg-1 min-1) was given during dialysis it enhanced the biological activity of heparin and prevented the activation and consumption of platelets. No adverse effects were observed. The reduction in heparin requirements produced by prostacyclin should make dialysis, safer, particularly for patients at risk of bleeding, while preserving the biocompatibility of the dialysis circuit. It remains to be established whether prevention of platelet activation will confer long-term benefit by inhibiting the prothrombotic state induced by haemodialysis, thereby reducing the risk of atherosclerosis in uraemic patients.

The amino acid sequence of fragment A, an enzymically active fragment of diphtheria toxin. II. The cyanogen bromide peptides

Cyanogen bromide cleavage of Fragment A from diphtheria toxin at the four methionines present in each molecule resulted in five major peptides which were isolated and studied by sequence methods. These five peptides of 4, 11, 14, 63, and 101 residues account for all 193 residues in Fragment A and provide overlaps for the tryptic peptides from the maleylated protein. Two additional peptides were isolated and shown to be shorter forms (8 and 10 residues) of the COOH-terminal cyanogen bromide peptide (11 residues).

The amino acid sequence of fragment A, an enzymically active fragment of diphtheria toxin. I. The tryptic peptides from the maleylated protein

Six tryptic peptides ranging in size from 3 to 126 residues were isolated from maleylated Fragment A of diphtheria toxin after tryptic hydrolysis. These peptides accounted for all 193 residues found by amino acid analysis. After demaleylation, the six peptides were purified by chromatography on Sephadex G-50, coupled with paper chromatography and electrophoresis, and were analyzed by various methods. The compositions and properties of the peptides are reported. Almost 70% of the residues were positioned within these peptides.

The amino acid sequence of fragment A, an enzymically active fragment of diphtheria toxin. III. The chymotryptic peptides, the peptides derived by cleavage at tryptophan residues, and the complete sequence of the protein

Fragment A (21,145 daltons in its longest known form) may be derived from diphtheria toxin (60,000 daltons) by mild tryptic digestion and reduction. Purified Fragment A consists of a mixture of 3 molecules of 190, 192, and 193 residues; the first 190 residues are in common and correspond to the NH2-terminal region the toxin. All three species of Fragment A are active in catalyzing ADP ribosylation of elongation factor 2, an essential component of protein synthesis. This reaction inactivates the factor and is responsible for the toxin's action in inhibiting protein synthesis in animal cells. It is believed that Fragment A or similar enzymically active fragments released into the cytosol of toxin-treated cells mediate this inhibition. The complete amino acid sequence of Fragment A has been determined from 32 chymotryptic peptides, three peptides derived by chemical cleavage of Fragment A at its 2 tryptophan residues, five cyanogen bromide peptides, and six tryptic peptides from the maleylated protein.

Identification of interacting amino acids at the histone 2A--2B binding site

Histones 2A and 2B of calf thymus were cross-linked within intact nuclei by UV irradiation. This procedure induces the formation of covalent cross-links between noncovalently interacting residues in the histones of native chromatin. Tryptic peptide and partial sequence analysis of the cross-linked product has shown that the covalent linkage is between tyrosine-37, -40, or -42 (we have not yet determined which) of H2B and proline-26 of H2A. We conclude that these residues constitute part of the hydrophobic H2A--H2B binding domain within the nucleosomes of native chromatin.

Labetalol in severe and resistant hypertension

1 The efficacy of labetalol in the treatment of severe hypertension (diastolic greater than or equal to 115 mm Hg) was studied retrospectively. Ten patients were followed for more than 6 months. At 6 months, eight were well controlled and the mean dose in those was 975 mg daily. Four of these were receiving labetalol alone; two were on labetalol and diuretic only. 2 Three patients were resistant to doses of 1600, 1800 and 2400 mg daily respectively; two of these were controlled with increased doses of vasodilator drugs. In two cases labetalol had produced large falls in the standing BP while not influencing the supine BP. 3 Three other resistant patients were seen, of whom one merely required an increase in dose to 2200 mg daily and the addition of a diuretic. Both the others were elderly, had severe vascular disease, and suffered disabling postural hypotension on a dose of labetalol which did not influence the supine BP. 4 Labetalol can control severe hypertension. There remain patients whose supine BP is not influenced by a dose of labetalol which produces marked postural hypotension.

Technic of deep hypothermia and circulatory arrest in the neonate and infant

Most congenital heart anomalies now can be surgically corrected in a neonate or very young infant. Because their hearts are so small, it is advantageous to work in a bloodless and motionless operative field. Deep hypothermia with circulatory arrest provides this setting. Physiologic problems associated with hypothermia are minimized by inducing general vasodilatation with large doses of methylprednisolone. Surface cooling is done with ice blankets and small sandwich bags filled with crushed ice. The patient's temperature gradually falls to 75.2 F (24 C). After median sternotomy, core cooling can be used to bring the patient's temperature to the desired 68 F (20 C). Circulatory arrest is produced by draining blood into the reservoir and cross-clamping the great vessels and venae cavae. It can be maintained for up to 60 minutes. In infants over six months and over 6 kg (13.2 lb), moderate hypothermia 77 F (25 C) and low perfusion (1/4-1/3 of normal) with short periods (10 to 15 minutes) of circulatory arrest improve operative conditions and allow correction of the most complicated congenital heart defects.