Breed does not affect the association between murmur intensity and disease severity in dogs with pulmonic or subaortic stenosis

OBJECTIVES

To determine whether breed affects the ability of murmur intensity to predict the severity of stenosis in dogs with pulmonic stenosis or subaortic stenosis.

MATERIALS AND METHODS

Retrospective multi-investigator study of dogs with pulmonic stenosis or subaortic stenosis. Murmur intensity, assessed by a four-level classification scheme, was compared with echocardiographically-determined pressure gradient across the affected valve. Breeds represented by at least 10 dogs at any murmur intensity were compared to determine the effect, if any, of breed.

RESULTS

A total of 1088 dogs (520 with pulmonic stenosis and 568 with subaortic stenosis, representing 106 breeds and the mixed breed group) were included; 208 dogs had soft, 210 had moderate, 283 had loud and 387 had palpable murmurs. Fifteen breeds were represented by at least 10 dogs: five breeds with at least 10 dogs had soft murmurs (132 dogs), nine breeds had moderate murmurs (149 dogs), 10 breeds had loud murmurs (188 dogs), and 11 breeds had palpable murmurs (286 dogs). No breeds differed in stenosis severity from any other breeds within any murmur grade. Post hoc power calculations suggested that we would have been able to detect at least a moderate or large effect size, had one existed. Several dogs with soft murmurs had more-than-mild disease severity.

CLINICAL SIGNIFICANCE

Despite anecdotally perceived differences in the detection of heart murmurs between breeds, which have been proposed to potentially affect the interpretation of stenosis severity, we found no obvious breed effect in the ability to predict severity of stenosis.

Redirecting effector T cells through their IL-2 receptors

Fusion proteins constructed of a tumor-specific Ab joined to IL-2 (Ab-IL-2) have been used in the past to deliver cytokine directly to the site of tumor cells in vivo. These molecules mimic the activity of IL-2 and assist in activating and expanding antitumor effector cells. To enhance the cytolytic activity of CTL specific for peptide epitopes of the Her-2/neu tumor Ag presented by HLA-A*0201 molecules, a fusion protein was constructed consisting of a single chain Ab specific for Her-2/neu, linked to IL-2 (neu-Ab-IL-2). When added to a mixture of tumor cells and Her-2/neu-specific CTL, the protein was found to augment lysis of tumor cells. In addition, the hybrid molecule also promoted lysis of Her-2/neu expressing tumors by non-tumor-specific cloned T cell lines, including Th1 CD4 cells. Analysis of the mechanism of cytotoxicity revealed that the fusion protein mediates the formation of stable conjugates between T cells expressing IL-2R and tumor cells expressing Her-2/neu, resulting in lysis through the Fas-Fas ligand pathway. Lysis induction was independent of specific engagement by the TCR. When tested for its ability to enhance tumor cell eradication by Her-2/neu-specific CD8+ T cells in an adoptive transfer model in SCID mice, neu-Ab-IL-2 facilitated the elimination of tumor cells in vivo. Surprisingly, the combination of non-tumor-specific CD8+ T cells and fusion protein also induced a significant delay of tumor growth. This represents a novel approach for redirecting non-tumor-specific T cells to eliminate tumors.

Latanoprost treatment for glaucoma: effects of treating for 1 year and of switching from timolol. United States Latanoprost Study Group

PURPOSE

To determine the efficacy and safety of latanoprost treatment for 1 year in glaucoma patients, and to evaluate the effects of switching from timolol to latanoprost therapy.

METHODS

Latanoprost 0.005% was topically applied once daily without masking for 6 months in 223 patients with elevated intraocular pressure after previous treatment with latanoprost once daily or 0.5% timolol twice daily for 6 months in a multicenter, randomized, double-masked, parallel group study.

RESULTS

Compared with baseline values before treatment, a significant (P < .0001) diurnal reduction in intraocular pressure of 6 to 8 mm Hg was maintained with minimal fluctuation for the duration of treatment. When treatment was switched from timolol to latanoprost, intraocular pressure was reduced by 1.5 +/- 0.3 mm Hg (mean +/- SEM; 8% change in intraocular pressure; 31% of the intraocular pressure reduction produced by timolol; P < .001) compared with the change in intraocular pressure in patients remaining on latanoprost therapy. Of the patients initially enrolled, 95% successfully completed treatment. There was a slight overall increase in conjunctival hyperemia in patients who switched from timolol to latanoprost, but no change in those who continued latanoprost. The timolol-induced reduction of resting heart rate returned to baseline levels after switching to latanoprost. Of the 247 patients treated with latanoprost during the masked and/or open-label studies, 12 (5%) demonstrated a definite (n = 4) or possible (n = 8) increase in iris pigmentation.

CONCLUSIONS

Latanoprost is a well-tolerated ocular hypotensive agent that appears to be more effective than timolol in reducing intraocular pressure. The increase in iris pigmentation appears to be harmless but requires further investigation.

Tolerance to p53 by A2.1-restricted cytotoxic T lymphocytes

Elevated levels of the p53 protein occur in approximately 50% of human malignancies, which makes it an excellent target for a broad-spectrum T cell immunotherapy of cancer. A major barrier to the design of p53-specific immunotherapeutics and vaccines, however, is the possibility that T cells may be tolerant of antigens derived from wild-type p53 due to its low level of expression in normal thymus and lymphohemopoetic cells. The combination of p53 deficient (p53-/-) and p53+/+ HLA-A2.1/Kb transgenic mice was used as a model to explore the possibility that A2.1-restricted cytotoxic T lymphocytes (CTL) are functionally tolerant of self peptides derived from the wild-type p53 tumor suppressor protein. A2.1-restricted CTL specific for a naturally processed p53 self-epitope spanning residues 187-197 were completely aborted in p53+/+ as opposed to p53-/- transgenic mice. In contrast, CTL specific for a second self-epitope spanning residues 261-269 of the murine p53 sequence were detected in both p53-/- and p53+/+ A2.1/Kb transgenic mice. However, the avidity of the CTL effectors obtained from p53+/+ mice was 10-fold lower than that obtained from p53-/- mice, again suggesting elimination of CTL with high avidity for the A2.1-peptide complex. The circumvention of functional tolerance of high avidity CTL may therefore be a necessary prerequisite for optimizing immunotherapy against A2.1-restricted wild-type p53 epitopes in humans.

Identification of Her-2/Neu CTL epitopes using double transgenic mice expressing HLA-A2.1 and human CD.8

The Her-2/neu protooncogene is associated with malignant transformation and aggressive disease. Because of its overexpression in tumor cells and because it has been shown to be immunogenic, this protein represents an excellent target for T-cell immunotherapy. By identifying potential HLA-A2.1-binding peptides from the Her-2/neu sequence, peptides were selected as candidate T-cell epitopes. The immunogenicity of each peptide was evaluated by priming double transgenic mice expressing both the human (hu) CD8 and HLA-A2.1 molecules with synthetic peptides corresponding to these sequences. Because of the lack of interaction between murine CD8 and HLA-A2.1, expression of huCD8 on murine cells facilitates recognition of HLA molecules on human tumor cell lines. This led to the identification of two peptides that elicit an A2-restricted CTL response, one of which has not been previously identified. Both peptide-specific CTL populations were able to specifically lyse A2.1 and Her-2/neu expressing human tumor cells originating from a variety of tissues, demonstrating the utility of this murine model in identifying peptides presented by human cells. However, several Her-2/neu peptides previously reported to be immunogenic for human CTL were found not to be immunogenic in transgenic mice. The basis for these discrepancies is discussed.

Prolonged inhibition of IgE production in mice following treatment with an IgE-specific immunotoxin

The synthesis of IgE antibodies by B cells is the first in a series of steps resulting in an allergic response. To eliminate IgE-bearing B cells and thereby prevent IgE production, we have developed an immunotoxin (ITA) composed of the non-anaphylactic 84.1c anti-mouse IgE mAb and the A chain of ricin (ricin A). This ITA specifically inhibited the induction of IgE synthesis by lipopolysaccharide plus interleukin-4 (LPS + IL-4) in vitro, and antigen-specific IgE production in vivo in adult mice. A single dose of anti-IgE ITA, given within a week (either before or after) of antigen challenge completely abolished antigen-specific primary IgE responses. No IgE production was seen for 2 months after ITA treatment. Following antigenic re-challenge, a suppressed secondary response (over 50% reduction) was still seen in the ITA-treated mice, 100 days after immunization. The results of this study demonstrate the potential use of anti-IgE toxin conjugates for the suppression of periodic (seasonal) allergic outbreaks.

Specific elimination of IgE production using T cell lines expressing chimeric T cell receptor genes

B cells that are destined to secrete IgE express a membrane-bound form of IgE (mIgE) on their cell surface. Thus, elimination of such mIgE-positive cells should result in the suppression of IgE production, thereby alleviating the symptoms of IgE-mediated allergy. In this study, we examined, in a model system, whether IgE-specific effector T cells can be used specifically to eradicate IgE-producing B cells. To this end, we endowed T cells with anti-IgE specificity using chimeric T cell receptors (cTCR) containing the variable region domain (Fv) of the 84.1c non-anaphylactic anti-mouse IgE monoclonal antibody (mAb). Two configurations of chimeric receptor were used: in the first, we combined the heavy and light variable region chains of 84.1c with the constant (C) regions of the TCR alpha and beta chains. The second construct consisted of a chimeric single-chain receptor (scFvR), composed of a single-chain Fv region of the 84.1c antibody and the C beta domain of the TCR. Following transfection of the cTCR or the scFvR genes into the murine MD.45 cytotoxic T cell hybridoma or the Jurkat human T cell line, functional expression of IgE-specific chimeric receptors was detected on the cell surface. The transfected cells secreted interleukin-2 upon stimulation with immobilized IgE or fixed IgE-producing hybridoma cells. Moreover, cytotoxic T cell hybridomas expressing the chimeric receptor genes specifically eliminated IgE-secreting B cells in vitro, resulting in isotype-specific suppression of IgE production.

The use and clinical importance of a substrate-specific electrode for rapid determination of blood lactate concentrations

OBJECTIVE

To determine the validity and clinical importance of a newly developed amperometric, enzymatic, substrate-specific electrode for the rapid measurement of circulating lactate concentrations.

DESIGN

A prospective multiexperiment study.

SETTING

The critical care medicine research laboratory, intensive care unit (ICU), emergency department (ED), and general wards of a university-affiliated hospital.

PATIENTS

A total of 1218 patients and control subjects were studied on one or more occasions.

INTERVENTIONS

Blood lactate concentrations, descriptive data, physiological parameters, and outcome results were determined in various patient populations.

MAIN OUTCOME MEASURES AND RESULTS

Experiment 1: Lactate determinations performed with the new substrate-specific electrode were compared with two laboratory reference methods. Blood samples from 80 ICU patients and 165 ED patients formed the basis of this first experiment. There was excellent agreement between the test instrument and the two reference methods as reflected by bias (with reference method 1, 0.19 mmol/L; reference method 2, 0.09 mmol/L), precision (with reference method 1, +/- 0.47 mmol/L; reference method 2, +/- 0.34 mmol/L), and correlation data (with reference method 1, r = .92; reference method 2, r = .98). Experiment 2: The new test microchemistry instrument was used to analyze blood samples from 927 patients. The mean (SE) blood lactate concentrations in the various patient populations were 1.26 (0.04) mmol/L for control subjects (n = 85), 1.52 (0.03) mmol/L for general ward patients (n = 489; P < .001 vs normal subjects), 2.34 (0.15) mmol/L for ICU patients (n = 180; P < .001 vs normal subjects and general ward patients), and 2.44 (0.15) mmol/L for ED patients (n = 173; P < .001 vs normal subjects and general ward patients). None of the normal subjects and only one (0.2%) of 489 nonhypotensive general ward patients had a blood lactate value greater than 4 mmol/L. Circulating lactate concentrations greater than 4 mmol/L were 98.2% specific in predicting the need for hospital admission in patients presenting to the ED. Furthermore, lactate concentrations greater than 4 mmol/L were 96% specific in predicting mortality in hospitalized nonhypotensive patients. Experiment 3: Blood samples from 46 hypotensive ICU and ED patients and from 353 nonhypotensive ICU and ED patients (the latter samples were derived from experiment 2) were analyzed. A statistically significant difference was noted between the mean (SE) lactate concentration in hypotensive patients in the ICU and ED (4.75 [0.75] mmol/L) when compared with nonhypotensive ICU and ED patients (2.28 [0.10] mmol/L; P < .001). Furthermore, blood lactate values greater than 4 mmol/L were 87.5% specific in predicting mortality in hypotensive patients.

CONCLUSIONS

Lactate determinations performed using the new test instrument are precise and accurate. Blood lactate concentrations greater than 4 mmol/L are unusual in normal and noncritically ill hospitalized patients and warrant concern. In hospitalized (non-ICU) nonhypotensive subjects, as well as in critically ill patients, a blood lactate concentration greater than 4 mmol/L may portend a poor prognosis.

Six week safety study of 2% MK-927 administered twice daily to ocular hypertensive volunteers

Ocular hypertensive patients were enrolled in a 6-week double-masked safety study of 2% MK-927 (27 patients), a topically active carbonic anhydrase inhibitor, administered bilaterally b.i.d.; 9 additional patients received 0.5% timolol as the control agent. Intraocular pressure (IOP) was measured weekly prior to a.m. drug administration; twelve hour diurnal curves were performed prestudy and at 3 and 6 weeks. The mean reduction of IOP prior to a.m. drug administration ranged from 1.2 +/- 4.4 mm Hg (SD) to 3.0 +/- 4.2 mm Hg with MK-927 and from 4.7 +/- 3.9 mm Hg to 8.8 +/- 0.6 mm Hg with timolol. Mean outflow facility measured tonographically prestudy and on days 33 to 42 four hours after a.m. drug administration was unchanged in both groups. Corneal sensitivity (Cochet-Bonnet), corneal thickness (ultrasound pachymetry), Schirmer tear testing, and extensive ophthalmologic and medical examinations, and hematologic studies were not substantially altered throughout the study. In this longest chronic administration study to date, MK-927 did not cause adverse ocular or systemic side effects.

CD4 and CD8 accessory molecules function through interactions with major histocompatibility complex molecules which are not directly associated with the T cell receptor-antigen complex

Both the subset-specific, CD4 and CD8 T cell accessory molecules and the antigen-specific T cell receptor (TcR) interact with major histocompatibility complex (MHC) class I and class II molecules on the surface of antigen-presenting cells. We analyzed whether the CD4/CD8 molecules exert their accessory function through binding with the same MHC molecules which participate in the TcR-antigen-MHC complex. We utilized a CD4-, CD8-, class I-allospecific T cell hybridoma which functionally manifests both cytotoxic T lymphocyte (CTL) and T helper1 (Th1) phenotypes, and rendered it bispecific by transfecting it with genes encoding either a class II-restricted, 2,4,6-trinitrophenyl (TNP)-I-Ad-specific TcR or a non-MHC-restricted chimeric TcR, composed of a variable part of an anti-TNP antibody. Expression of either CD4 or CD8 transgenes in these hybridomas enhanced and augmented their reactivity towards the appropriate target cells regardless of the type of TcR-MHC interaction. Thus, class I-specific responses could be enhanced through CD4-class II interactions, and class II-restricted responses could be augmented through CD8-class I interactions. Furthermore, these accessory molecules also potentiated TNP-specific responses by the chimeric TcR which is MHC unrestricted. The accessory molecules facilitated both interleukin 2 (IL2) production and cytolytic activity by shortening the activation time and rendering the cells responsive to lower antigenic stimuli. The degree of activity of the T cell hybridomas correlated with the level of accessory molecule expression and was not related to the effector function mediated by the cells. Anti-CD4 or -CD8 antibodies completely inhibited the activity of transfectants expressing the corresponding accessory molecule, regardless of the MHC type of the TcR interaction. Such antibodies blocked direct TcR stimulation provided by either anti-T3/Ti antibodies or lectins, but could not inhibit the activation through agents that bypass the TcR such as phorbol 12-myristate 13-acetate plus ionophore. Taken together, these studies demonstrate that the CD8/CD4 molecules can exert their accessory function through interactions with MHC molecules which are not directly associated with the TcR-Ag-MHC complex, and that this accessory effect is associated with TcR-mediated triggering at an early stage of the signaling process and is not related to the effector mechanism assigned to the CD4 and CD8 T cell subsets.

Southern blot analysis of BII cell line--a putative variant of HL-60

Southern blot analysis of various genes was used to compare the human promyelocytic leukemia cell line HL-60 and the BII cell line, which reportedly arose as a spontaneous differentiation inducer-resistant variant from an HL-60 culture. Granulocyte-macrophage colony stimulating factor gene restriction fragment polymorphism, due to a partial deletion of one of the alleles of this gene in HL-60, was not observed in the BII cells. Furthermore, the p53 oncogene, most of which is deleted in the HL-60 cell line, was found to be intact in the BII cell line. Human leukocyte antigen typing revealed that the two cell lines shared the A locus but differed at the B locus. Several unique restriction fragments hybridizing to human leukocyte antigen class I and DR beta gene probes were observed in the DNA digests of each cell line. Altogether these data provide definitive evidence that BII represents a human cell line of different origin than HL-60. Further lineage determination of this cell line could add a useful member to the group of leukemic cell lines.

Continent, nonrefluxing urinary reservoir constructed from ileum: report of two cases

Most procedures for diverting urine sacrifice continence, but Kock's modification of the ileal conduit promises the ideal of appliance-free urine storage with voluntary control of emptying. The authors report on two men who underwent this procedure. One was a paraplegic who had total urinary incontinence after a sphincterotomy. The other had a carcinoma of the rectosigmoid obstructing the right ureter. He had congenital bladder exstrophy and had undergone ureteric implantation into the sigmoid colon at 3 years of age. In both patients, the reservoir was created from an isolated 60-cm segment of the middle portion of small bowel. Two nipple valves were created - one to prevent reflux and one to provide continence of urine. Follow-up was 27 and 17 months respectively. One patient had his outlet valve revised because of sliding and incontinence. He is now completely continent of urine and he intubates his reservoir three to four times daily. Postoperatively, the second patient had a leak at the ureteroileal anastomosis, but this healed spontaneously. The continent urinary diversion is a major intestinal operation and should not be performed in conjunction with exenteration. It should be confined to a few centres where greater experience can be accumulated.

Laser trabeculoplasty. A prospective study of treatment variables

Forty-five phakic eyes with open-angle glaucoma and uncontrolled intraocular pressure underwent laser trabeculoplasty. Each eye was assigned randomly to one of three treatment groups: group 1, 100 spots over 360 degrees; group 2, 50 spots over 180 degrees; or group 3, 50 spots over 360 degrees. A 50-micron spot was aimed at the anterior meshwork; power and time were varied to achieve a blanch. Forty-four eyes were followed up for at least four weeks without further intervention. The mean IOP before therapy and the initial IOP elevation were similar in all groups. After four weeks, the mean IOP reductions in 15 eyes in group 1, 15 eyes in group 2, and 14 eyes in group 3 were not significantly different. However, significantly more eyes in group 1 demonstrated a greater than 12 mm Hg reduction in IOP than eyes in the other groups. Group 2 tended to have the fewest eyes with reduced medications.

Serum hormones and lipoproteins in benign breast disease

Seventeen young women with clinically confirmed mammary dysplasia and six age-matched controls were treated with alpha-tocopherol. Serum samples collected during the luteal phase of each woman at monthly intervals for the 4-month duration of the study were analyzed for serum luteinizing hormone, follicle-stimulating hormone, and prolactin concentrations by radioimmunoassay and for lipoprotein levels by a combination of precipitation, ultracentrifugation, and enzymatic techniques. Fifteen patients showed objective and subjective remission from disease. While prolactin levels did not change significantly, elevated levels of luteinizing and follicle-stimulating hormones were decreased to normal levels. Ratios of serum cholesterol to high-density lipoprotein cholesterol decreased; high-density lipoprotein and free cholesterol associated with low-density lipoproteins increased as a result of therapy. The results suggest that alpha-tocopherol may serve as an effective agent not only to treat patients with benign breast disease but also to normalize abnormal hormone and lipid levels in subjects at high risk for breast cancer.