Transitioning to a Plant-Based Menu in Childcare: Identifying the Nutritional, Financial, and Logistical Considerations

International health organizations have called for a shift towards more plant-based foods as a way of promoting both individual health and environmental sustainability. Given the high percentage of children in Canada who attend childcare and the high volume of food provided in childcare, transitioning menus to incorporate plant-based foods could have important implications for both planetary and child health. The purpose of this case study is to describe a childcare centre's transition to a plant-based menu. A detailed nutritional analysis of the menu was conducted. The financial and logistical implications of the transitions to a plant-based menu were also assessed. Nutritional analysis revealed that the plant-based menu met or exceeded the daily nutrient requirement for all the key nutrients explored. Financially, the transition led to a 9% reduction in food costs. Logistically, the transition led to improved efficiency and safety with regard to food preparation, with substantially fewer tailored meals due to allergies and dietary restrictions required after the transition. These novel findings are relevant for food service administrators interested in transitioning to a plant-based menu as well as public health dietitians who could support the transition.

Long-term outcomes of an acellular dermal matrix for the treatment of complex cryptoglandular anal fistula: a pilot study

Backgound

Effective, standardized treatments for complex anal fistula (CAF) still represent a clinical challenge. Emerging procedures attempted to achieve the healing rates of fistulotomy whilst preserving sphincter function. Acellular dermal matrix (ADM) used as a plug inserted through the fistulous tract is among newer treatment options. Varying success rates have been reported, most with short-term follow-up. The aim of this study was to report the long-term results of ADM-plug for CAF.

Methods

Retrospective analysis of a prospective database of patients treated with CAF. All consecutive patients presenting at two tertiary centers (Vall d’Hebron University Hospital and Bellvitge University Hospital, Barcelona, Spain) between November 2015 and March 2019 with a single, cryptoglandular CAF were evaluated for treatment with an ADM-plug were included. The primary endpoint was absence of discharge at clinical examination at 12 month follow-up.

Results

Twenty-two patients were included [7 women and 15 men, median age 56 (33–74) years]. Most patients had high transsphincteric fistulas (63.6%). The median follow-up was 42 (21–53) months. The 12 month success rate was 68.2%, with an overall healing rate of 59.1%. 77.8% of recurrences occurred within 12 months from surgery. One plug extrusion was observed. No major complications or mortality occurred during the follow-up. Patients did not report any worsening of fecal continence.

Conclusions

This pilot study showed that more than half of patients with CAF could benefit from ADM-plug placement, preserving continence. A minimum follow-up of 12 months is recommended, because most recurrences occur during the first year.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10151-022-02593-1.

Abstract P5-05-12: Progesterone drives ER-positive and triple negative breast cancer cell proliferation through progesterone receptor membrane component 1

Introduction: The role of progesterone and its receptors in breast cancer progression continue to be studied but remain controversial. Progesterone membrane receptors with the ability to regulate kinase signals, mediating breast cancer proliferation have been demonstrated. Increased expression of the Progesterone Receptor Membrane Component 1 (PGRMC1), a heme – binding protein with the ability to interact and stabilize epidermal growth factor receptor (EGFR) is frequently found in breast cancer tissue. Some evidence suggests that progesterone can stimulate and regulate breast cancer cell proliferation. The basis of the signaling mechanisms by which Progesterone exerts its function remains largely unknown. Both the nuclear and membrane progesterone receptors could play a significant role in the development and progression of breast cancer and both could become viable therapeutic options. We, aim to investigate the role of PGRMC1 in progesterone driven breast cancers.

Materials and Methods: Human breast tissues were utilized to identify PGRMC1 expression along with a panel of normal and breast cancer cell lines. Two breast cancer cell lines (ZR-75-1 and MDA-MB-468) were selected and treated with progesterone and AG-205 (PGRMC1 inhibitor) at different concentrations to assess optimum dosage. We performed MTS assay, qRT-PCR, Western blot, immunofluorescence, immunohistochemistry and flow cytometry for measuring cell proliferation, apoptosis and key markers involved in these processes. We also performed an in silico analysis to compare the expression of PGRMC1 in various cell lines and breast cancer tissues.

Results: Immunohistochemistry demonstrated strong staining for PGRMC1 in human breast cancer tissue compared to normal tissue. Increased PGRMC1 expression was observed specifically in ZR-75-1 and MDA-MB-468 cells by qRT-PCR, western blot and immunofluorescence, these results were validated and compared to microarray-based gene expression analysis of breast cell lines and breast tumor data sets. Progesterone treatment increased cell proliferation in a dose dependent manner while AG-205 decreased cell proliferation in a dose dependent manner in ZR-75-1 and MDA-MB-468. Minimal effects of AG-205 were observed in normal breast epithelial cells. AG-205 also, induced apoptosis in both ZR-75-1 and MDA-MB-468 cell lines. Furthermore, short-term treatment of progesterone increased both mRNA and protein expression of PGRMC1. Key markers of cell proliferation (pAKT, CCND1, pEGFR, pmTOR) and apoptosis (PTEN, Bcl2, Bax, Bim) revealed that PGRMC1 facilitated the proliferative effect of progesterone. Interestingly progesterone increases phosphorylation of EGFR and treatment of AG-205 alters EGFR expression in a dose dependent manner.

Conclusion: Our data demonstrates that PGRMC1 plays a prominent role in regulating progesterone driven cell proliferation in both ER-positive and triple negative breast cancer cells. These initial findings uncover the potential of PGRMC1 as a therapeutic target for breast cancers.

Citation Format: Pedroza DA, Subramani R, Galvez A, Lakshmanaswamy R. Progesterone drives ER-positive and triple negative breast cancer cell proliferation through progesterone receptor membrane component 1 [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 P5-05-12.

Abstract P5-05-15: Pregnancy inhibits mammary carcinogenesis by persistently altering the hypothalamic-pituitary axis

Pregnancy, carried to term at an early age, is probably the best natural protection against breast cancer development. The relative life-long breast cancer risk for women that give birth to their first child before the age of 20 years is approximately half that of nulliparous women. In contrast, if a woman undergoes her first full-term pregnancy after the age of 35, her risk for breast cancer is increased even more than nulliparous women. In the current generation many women are career oriented and have children later in life. Universally the average age at first birth is on the rise. It is critical to understand the underlying mechanism of this protective effect of pregnancy against breast cancer to develop novel prevention strategies to reduce the risk of breast cancer without women having to undergo pregnancy early in life. Earlier, we and others have demonstrated that post-pregnancy there were persistent changes in circulating levels of hormones. In order to understand the significance of these systemic changes we determined alterations in the hypothalamic-pituitary axis in parous rats. In particular, we examined the static and dynamic alterations in the hypothalamic-pituitary axis in response to pregnancy. Seven weeks old female Lewis rats were injected with the chemical carcinogen N-methyl-N-nitrosourea (MNU) at a dose of 50mg/kg body weight intraperitoneally. Two weeks post-carcinogen treatment these rats were housed with a male rat. On the observation of the vaginal plug the male was removed from the cage. Once the rats gave birth they nursed the pups for three weeks and were weaned after that period. Mammary tumorigenesis was monitored through weekly palpation for a period of nine months. A subset of rats at 6, 12 and 24 weeks post-weaning were used to study static and dynamic changes in the level of hormones. We investigated the static alterations in the hypothalamic-pituitary axis in response to pregnancy by measuring the levels of thyrotropin releasing hormone (TRH), growth hormone releasing hormone (GHRH), somatostatin (SS), dopamine (DA), growth hormone (GH) and prolactin (PRL). Next we investigated if the dynamic alterations in the hypothalamic-pituitary axis in response to pregnancy. Control and parous animals were subjected to secretogogue treatments (Growth Hormone Related Peptide 6 for GH and Perphenazine for PRL) and the levels of GH and PRL were measured. We also isolated the pituitary and treated them with the secretogogues and measured the levels of GH and PRL. Our data demonstrated that pregnancy resulted in persistent static and dynamic alterations in circulating levels of hormones. Parous rats response to the secretogogues was severely blunted compared to the control nulliparous rats. The levels of TRH, GHRH, GH and PRL were significantly lowered in parous rats while DA and SS levels were higher in nulliparous rats. As expected mammary carcinogenesis was significantly inhibited in parous rats. Overall, these preliminary results suggest that pregnancy induces persistent changes in hypothalamic-pituitary axis, which results in a lowered hormonal promotion environment resulting in inhibition of mammary carcinogenesis.

Citation Format: Subramani R, Galvez A, Pedroza D, Lakshmanaswamy R. Pregnancy inhibits mammary carcinogenesis by persistently altering the hypothalamic-pituitary axis [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 P5-05-15.

Platelet Interaction with Vessel Wall and Collagen in Pigs with Homozygous von Willebrand’s Disease Associated with Abnormal Collagen Aggregation

A subgroup of pigs with von Willebrand’s disease from the Mayo Clinic stock shows abnormal platelet aggregation in response to collagen [vWD-Homo(-)], in contrast to the normal aggregation responses observed in the main colony of pigs with homozygous vWD [vWD-Homo(+)]. This subgroup has been characterized at Mayo as a storage pool deficiency due to the reduced levels of ADP and Serotonin in the platelet dense granules. In the present studies, an ex-vivo perfusion chamber was utilized to investigate the deposition of 111In-labeled platelets on aortic subendothelium and collagen type I exposed to blood from vWD-Homo(-), vWD-Homo(+) and normal animals. Both non-anticoagulated and heparinized blood were exposed for wall shear rates ranging from 212 sec-1 to 3380 sec-1 and exposure times as long as 30 min. An enhanced decrease in platelet deposition in the vWD-Homo(-) animals was observed compared to vWD-Homo(+) animals. The decrease was observed primarily at the higher shear rates and was more pronounced in the absence of heparin and on the collagenous substrate. Thus, the abnormality in collagen-induced aggregation, which has been characterized as a storage-pool type defect, results in a decreased platelet deposition compared with that produced by severe vWD alone.

Correction to: Distal Doppler-guided transanal hemorrhoidal dearterialization with mucopexy versus conventional hemorrhoidectomy for grade III and IV hemorrhoids: postoperative morbidity and long-term outcomes

The article "Distal Doppler-guided transanal hemorrhoidal dearterialization with mucopexy versus conventional hemorrhoidectomy for grade III and IV hemorrhoids: postoperative morbidity and long-term outcomes", written by L. Trenti, S. Biondo, A. Galvez, A. Bravo, J. Cabrera, E. Kreisler, was originally published electronically on the publisher's internet portal (currently SpringerLink) on [27 April 2017] without open access. With the author(s)' decision to opt for Open Choice the copyright of the article changed on 7 June, 2018 to

Emulsifying Properties of Chemically Deamidated Corn (Zea Mays) Gluten Meal

Corn gluten meal is a by-product of starch production that is readily available. Corn protein isolates have limited applications due to their hydrophobic nature, low solubility and limited functionality as emulsifiers. In this study, a mild acidic treatment of corn gluten meal was performed in order to achieve deamidation of asparagine and glutamine residues and modify the interfacial behavior of this byproduct. A 0.1 N HCl treatment for 6 h at 70 °C rendered a deamidation degree of 20.4%, which increased the emulsification activity index of corn gluten meal from 6.8 to 16.8 m2/g protein, with a remarkable increase in emulsion stability from 0 to 90.6% oil retention. Proteins participating in the emulsion were separated by SDS-PAGE and the main polypeptides were identified as alpha and beta-zeins. After deamidation, protein dissociation and unfolding due to the obtained negative charges resulted in enhanced functionality.

Evaluation of the quality and treatability of leachate produced at a landfill connected to an urban waste composting and recovery plant at Alhendin (Granada, Spain)

The leachate produced at a landfill adjoining an urban waste composting and recovery plant at Alhendin (Granada, Spain) was sampled for a period of more than 3 years from February 2003 until July 2006. The main pollutant parameters (COD, BOD(5), solids, nitrogen, main anions and cations, pH, Eh and conductivity) were analysed with the aim of selecting the most effective treatment for the leachate. The results obtained showed high concentrations of different pollutants with COD and BOD(5) values up to 74,133 mg/L and 39,000 mg/L respectively. Seasonal changes in leachate composition were mainly attributed to differences in rainfall, temperatures, and evaporation rates. Our study classified the Alhendin landfill leachate as a partially stabilized leachate because of: (i) its management strategies (storage at artificial ponds and recirculation); (ii) the coexistence in the landfill of active and closed cells with wastes of different ages and at different decomposition phases. The leachate quality data obtained was statistically evaluated using various statistical tools. A good correlation was found between many of the parameters analysed, some of which also showed good linear regressions. Principal component analysis allowed the reduction of most of the parameters analysed to four components: Component 1 (K(+), Mg(2 +), FTS, VDS, VTS, Na(+) and Cl(-)), component 2 (BOD(5)), component 3 (TDS, TS, FDS and conductivity) and component 4 (pH, FSS, Eh and VSS). The results obtained are valuable for the selection of the best leachate treatment option. A combination of a physicochemical treatment and a fixed film biological system is recommended for this leachate.

Effect of sorafenib on chemotherapy resistance and refractoriness in castration-resistant prostate cancer (CRPC)

e16105

Background: There is no standard for CRPC once chemotherapy fails. In studies employing docetaxel (D), 35–39% of pts did not complete therapy due to progression and only 45–50% had a PSA response. This implies that many pts develop resistance to D. Sorafenib is a multi kinase inhibitor with antiangiogenesis properties. We hypothesized that sorafenib could overcome chemotherapy resistance in these pts. Methods: Eligible pts must have progressed while on either D or mitoxantrone (M). They received sorafenib at 400 mg orally twice/daily in addition to the chemotherapy agent they were on. Sorefinib/chemotherapy combination was given for a maximum of 6 cycles followed by sorafenib monotherapy until progression. Primary end point was safety of the sorafenib/chemotherapy combination. Secondary end points included the overall clinical benefit calculated as the sum of complete response (CR), partial response (PR), and stable disease (SD), toxicity, and time to disease progression (TTP). Results: To date, 15 pts have been enrolled; 14 are evaluable. Eleven pts were on D and 4 on M. Median age was 68 (range 61–83), median PSA was 111.2 ng/ml (13.6–1703.9). Nine pts (60%) had visceral and bone disease. Median PSA-DT pre-study was 2 months (0.5–6) and median time from last chemotherapy to starting study was 4 weeks. Median number of given cycles was 6.5 (2–12). Six pts did not require dose reduction, 2 others were re-escalated to the full dose. Sorafenib was safely combined with chemotherapy with 6 pts experiencing grade 3 fatigue, 3 developing grade 3 hand/foot syndrome, and 1 experiening grade 3 diarrhea. Eleven pts (73%) had SD radiographically that lasted a median of 6.7 months. In all, 6 out of 14 pts (42%) had a PSA decline after adding sorafenib and 3 (21%) had stable PSA. Of these 9 pts (PR+SD), 2 never doubled their PSA. Two pts had PSA decline after withdrawing sorafenib. Median TTP for PSA was 3.75 months. PSA responses did not correlate with radiographic changes or clinical benefit. With a median follow-up of 8 months, 5 pts (33%) remain alive with 1 continuing on therapy without progression. Conclusions: Sorafenib overcomes chemotherapy-refractoriness and failures in CRPC.

[Table: see text]

Erlotinib has activity in androgen-independent prostate cancer (AIPC) patients who are chemotherapy-naive: A phase II trial

15606

Background: Mechanisms of hormone resistance for AIPC are variable. One proposed mechanism is the over expression of the epidermal growth factor receptor (EGFR) which in turn stimulates proliferation through its pathway. We aimed to determine the efficacy of an oral anti-EGFR inhibitor (erlotinib) in this patient population that was chemotherapy-naive. The primary end point was to evaluate the overall clinical benefit defined as the sum of complete response (CR), partial response (PR), and stable disease (SD). Methods: Between January and December 2006, sixteen patients were enrolled onto this phase II study. Median age was 78 years (66–85). Median PSA was 61.9 (9.2–800.2). Median time from initial diagnosis until starting Erlotinib was 7.8 years. Erlotinib was given daily at 150 mg until disease progression. Patients were evaluated every 2 weeks for toxicity. Response assessment took place every 2 cycles (each cycle was 4 weeks). Evaluations included computed tomography of measurable disease areas, bone scans, and serum PSAs. Patients who progressed radiographically but maintained a PSA response or those who progressed biochemically but maintained a radiographic response were considered stable and were allowed to continue on study. Results: Sixteen patients were enrolled with 14 being evaluable at this time (2 patients are early in their course). Median cycles received is 2 (range 1.5–12). One patient achieved a PR and continues on Erlotinib after one year of enrollment. Three patients demonstrated stable disease but two of them later progressed. One patient withdrew after 9 days of starting therapy due to fatigue and poor taste. All other patients developed disease progression after two cycles of therapy. The calculated overall clinical benefit was 28% (4 responses out of 14 patients). One patient died from pneumonia and seizures unrelated to Erlotinib as confirmed by an autopsy that showed progression in the central nervous system. Erlotinib was well-tolerated with skin rash and diarrhea being the most common toxicities. Conclusions: Erlotinib has clinical activity as a single agent in AIPC. Updated results of this ongoing study will be presented at the meeting. Further studies with this agent alone or in combination are warranted.

No significant financial relationships to disclose.

A rapid and strong apoptotic process is triggered by hyperosmotic stress in cultured rat cardiac myocytes

In all cell types, the maintenance of normal cell volume is an essential homeostatic function. Relatively little is known about the induction of apoptosis by hyperosmotic stress and its molecular mechanism in terminally differentiated cardiac myocytes. We compared the apoptotic response of cultured neonatal rat cardiomyoctes to hyperosmotic stress by sorbitol (SOR) with those induced by doxorubicin (Doxo) or angiotensin II (Ang II). We also examined the apoptotic-signaling pathway stimulated by the hyperosmotic stress. Apoptosis was assessed by the observation of: (1) cell viability, (2) DNA fragmentation detected by the TUNEL method and by agarose gel electrophoresis, and (3) poly(ADP-ribose)polymerase (PARP) degradation, and Bcl-XS and Bcl-XL levels by Western blot analysis. Exposure of cardiomyocytes to 0.3 M SOR for 24 h resulted in decreased cell viability and increased generation of oligosomal DNA fragments (2.5-fold of controls). At this time, 83 +/- 5% of SOR-treated myocytes were TUNEL-positive (vs 23.7 +/- 6.8% in controls; P<0.01). PARP levels also decreased by approximately 42% when cardiac myocytes were exposed to SOR. Hyperosmotic stress induced a more rapid and stronger apoptotic response in cardiomyocytes than Doxo or Ang II. In addition, SOR increased 3.2-fold Bcl-XS proapoptotic protein without changes in Bcl-XL antiapoptotic protein levels and in the p53-transactivating activity. Taken together, these results strongly suggest that hyperosmotic stress triggers cardiac myocyte apoptosis in a p53-independent manner, being earlier and stronger than apoptosis induced by Doxo and Ang II.

High remission rate in acute myeloblastic leukemia with only two days of chemotherapy

Twenty five patients with AML who had neither a history of toxic exposure or myelodysplasia were treated with a remission induction regimen consisting of two pulses of chemotherapy separated by 96 hrs. Each pulse consisted of cytarabine 2gm/m(2) (at t=0 and t=12 hrs) with mitoxantrone [30mg/m(2) ] administered immediately after the second cytarabine administration. Amifostine was administered three times a week [on Monday, Wednesday, and Friday] until the outcome of therapy was known. This regimen induced complete remissions in 15 of 17 patients less than 70 years of age and in 5 of 8 patients older than 70 years.

Optical properties of synthetic carbon nanoparticles as model of cosmic dust

Carbon nanoparticles synthesised by laser pyrolysis of small hydrocarbons are deposited at low energy on a silicon substrate. Infrared spectroscopy of the as-formed films are studied as a function of the synthesis parameters and post-treatments, such as annealing and heavy ion irradiation. Correlation between infrared spectroscopy and multiscale organisation of the samples is made through transmission electron microscopy, including image analysis. Changes in infrared spectra are analysed in terms of the carbon network building. The relevance of the results to model the structure and spectroscopy of carbon dust in the carbon-rich circumstellar media is discussed.

Poor prognosis acute myelogenous leukemia: 1 - response to treatment with high dose cytarabine/mitoxantrone/ethyol @ (Amifostine)

Twenty patients with poor prognosis AML and four patients in the blastic phase of a myeloproliferative disorder were treated with two 'pulses' of therapy each consisting of two doses of high dose araC (separated by 12 h) followed by a single dose of mitoxantrone. The pulses were separated by 96 h. Amifostine was then administered tiw. The median age of the population was 68 years with 88% of patients having had either a prior MDS, MPD or toxic exposure. The acute leukemia of 58% of patients either entered a CR or reverted to preleukemic state. For patients under 70 years of age, treatment produced 62% CRs with a leukemia free decision marrow in 77%. For patients over 70 years the CR rate was 27% with 36% of patients having a leukemia free decision marrow.

Suppression of telomerase activity and cytokine messenger RNA levels in acute myelogenous leukemia cells in vivo in patients by amifostine and interleukin 4

High levels of telomerase activity and high rates of cell proliferation are associated with a poor prognosis in acute myelogenous leukemia. Furthermore, cytokine production by leukemia cells is believed to play an important role in determining the proliferative characteristics of leukemia. The in vivo effects of two noncytotoxic agents on these parameters were determined in 33 acute myelogenous leukemia patients. Three daily doses of interleukin (IL) 4 or a single dose of amifostine reduced telomerase activity in the leukemia marrow cells in 7 of 9 and 11 of 13 patients, respectively. The administration of a single dose of amifostine resulted in a reduction in tumor necrosis factor alpha and IL-6 transcript levels in the marrow cells of 10 of 13 and 12 of 13 patients in which these transcripts were present. The administration of only three doses of IL-4 or a single dose of amifostine has a significant effect on leukemia cell parameters, which are believed to have a significant impact on the in vivo biology of the disease and on its response to remission induction therapy.

Cytokine gene activity in AML cells in vivo in patients

The proliferation of acute myelogenous leukemia cells is dependent upon cytokine stimulation. Additionally, there is a body of literature which reports that leukemia cells produce GMCSF, IL6, and other cytokines. The study reported here, using an rt-multiplex polymerase method, determined the presence or absence of transcripts in freshly obtained AML cells for the following cytokine or cytokine-related genes: IL 1beta, IL1ra, TNF alpha, GMCSF, IL6, flt 3, and hSCF. This demonstrated that leukemia cell populations usually contain transcripts for IL1beta, TNF alpha, flt 3 and flt 3 ligand in vivo and that transcripts for the other cytokines only appear after the leukemia cells are processed in vitro. The presence of TNF alpha transcripts appears to be associated with resistance to remission induction therapy. Furthermore, the transcript profile of the leukemia cells can change during remission induction therapy. The data also demonstrate the assessment of cytokine production by leukemia cells after in vitro manipulation should not be extrapolated to the in vivo situation.

Antagonistic action of the bacterium Bacillus licheniformis M-4 toward the amoeba Naegleria fowleri

Free-living amoebae belonging to the species Naegleria fowleri are known to be the etiological agents for a form of fulminant meningoencephalitis that is generally fatal (primary amoebic meningoencephalitis). In a broad bacterial screening from soil and water we have isolated three strains (M-4, D-13 and A-12) belonging to the species Bacillus licheniformis that have remarkable amoebicidal activity against Naegleria sp. and also against different Gram-positive and Gram-negative bacteria. Physical-chemical characteristics, partial purification and biological activities of a substance produced by the M-4 strain have been investigated. This substance (m-4) is stable at high temperature (up to 100 degrees C) and extremes of pH (2.5-9.5) and also at -20 degrees C for months. Its production is greatly influenced by oxygenation of the cultures and is probably related to the sporulation process of the bacterium. Scanning electron microscope observations reveal that amoebae are lysed after a few minutes contact with m-4.

Total pulmonary torsion without vascular compromise--a case report

A new case of pulmonary torsion is reported. Only 15 cases of this rare entity have been published in the literature, all of them either surgically treated short term or resulting in death. Small right-side pneumothorax following diagnostic transthoracic puncture seemed to be the mechanism of production. Because of the absence of acute clinical manifestations, fibroscopy, isotopic perfusion scanning, and hemodynamic and pulmonary angiographic studies were done. The lack of compromise in the pulmonary flow and venous pulmonary return explains the surprisingly good progress (ten months, at present) of the patient.

Use of toxins to study potassium channels

Potassium channels comprise groups of diverse proteins which can be distinguished according to each member's biophysical properties. Some types of K+ channels are blocked with high affinity by specific peptidyl toxins. Three toxins, charybdotoxin, iberiotoxin, and noxiustoxin, which display a high degree of homology in their primary amino acid sequences, have been purified to homogeneity from scorpion venom. While charybdotoxin and noxiustoxin are known to inhibit more than one class of channel (i.e., several Ca(2+)-activated and voltage-dependent K+ channels), iberiotoxin appears to be a selective blocker of the high-conductance, Ca(2+)-activated K+ channel that is present in muscle and neuroendocrine tissue. A distinct class of small-conductance Ca(2+)-activated K+ channel is blocked by two other toxins, apamin and leiurotoxin-1, that share no sequence homology with each other. A family of homologous toxins, the dendrotoxins, have been purified from venom of various related species of snakes. These toxins inhibit several inactivating voltage-dependent K+ channels. Although molecular biology approaches have been employed to identify and characterize several species of voltage-gated K+ channels, toxins directed against a particular channel can still be useful in defining the physiological role of that channel in a particular tissue. In addition, for those K+ channels which are not yet successfully probed by molecular biology techniques, toxins can be used as biochemical tools with which to purify the target protein of interest.

Purification and characterization of a unique, potent, peptidyl probe for the high conductance calcium-activated potassium channel from venom of the scorpion Buthus tamulus

An inhibitor of the high conductance, Ca2(+)-activated K+ channel (PK,Ca) has been purified to homogeneity from venom of the scorpion Buthus tamulus by a combination of ion exchange and reversed-phase chromatography. This peptide, which has been named iberiotoxin (IbTX), is one of two minor components of the crude venom which blocks PK,Ca. IbTX consists of a single 4.3-kDa polypeptide chain, as determined by polyacrylamide gel electrophoresis, analysis of amino acid composition, and Edman degradation. Its complete amino acid sequence has been defined. IbTX displays 68% sequence homology with charybdotoxin (ChTX), another scorpion-derived peptidyl inhibitor of PK,Ca, and, like this latter toxin, its amino terminus contains a pyroglutamic acid residue. However, IbTX possesses 4 more acidic and 1 less basic amino acid residue than does ChTX, making this toxin much less positively charged than the other peptide. In single channel recordings, IbTX reversibly blocks PK,Ca in excised membrane patches from bovine aortic smooth muscle. It acts exclusively at the outer face of the channel and functions with an IC50 of about 250 pM. Block of channel activity appears distinct from that of ChTX since IbTX decreases both the probability of channel opening as well as the channel mean open time. IbTX is a selective inhibitor of PK,Ca; it does not block other types of voltage-dependent ion channels, especially other types of K+ channels that are sensitive to inhibition by ChTX. IbTX is a partial inhibitor of 125I-ChTX binding in bovine aortic sarcolemmal membrane vesicles (Ki = 250 pM). The maximal extent of inhibition that occurs is modulated by K+, decreasing as K+ concentration is raised, but K+ does not affect the absolute inhibitory potency of IbTX. A Scatchard analysis indicates that IbTX functions as a noncompetitive inhibitor of ChTX binding. Taken together, these data suggest that IbTX interacts at a distinct site on the channel and modulates ChTX binding by an allosteric mechanism. Therefore, IbTX defines a new class of peptidyl inhibitor of PK,Ca with unique properties that make it useful for investigating the characteristics of this channel in target tissues.

Effect of peptide AS-48 on Enterococcus faecalis subsp. liquefaciens S-47

The enterococcal peptide AS-48 exerts a concentration-dependent bactericidal effect on Enterococcus faecalis subsp. liquefaciens S-47; cell rescue by cardiolipin and trypsin can be effected only in the first few minutes after antibiotic addition. Gramicidin-exposed cells are protected from killing by AS-48. Long-term and pulse incorporation of radiolabeled substrates into trichloroacetic acid-precipitable material, O2 consumption, and the ability to maintain intracellular potassium levels are impaired shortly after addition of AS-48.

High density lipoprotein plasma fractions inhibit aortic fatty streaks in cholesterol-fed rabbits

The effects of in vivo administration of high density lipoprotein-very high density lipoprotein (HDL-VHDL) on the development of aortic fatty streaks were studied in cholesterol-fed rabbits. The rabbits received a 0.5% cholesterol-rich diet for 8 weeks. During this period, the HDL-VHDL group was intravenously administered with 50 mg/week of homologous HDL-VHDL protein; the control group received normal saline (0.9% NaCl). HDL-VHDL fraction was obtained at density range 1.063 to 1.25 gm/ml by ultracentrifugation of normal rabbit plasma. Along the study, plasma lipid levels followed a similar profile in both groups. At the completion of the study, atherosclerotic-like lipid-rich lesions covered 37.9 +/- 6% (X +/- SEM) of the intimal aortic surface in the control group, and 14.9 +/- 2.1% in the treated group (p less than 0.001). The values of total and free cholesterol, esterified cholesterol, and phospholipids deposited within vessel wall were significantly lower in the aortas of the HDL-VHDL treated group than those in the control group. Cholesterol accumulation in the livers was also significantly lower (p less than 0.01) in the treated group than in the control. We concluded that administration of homologous HDL-VHDL lipoprotein fraction to cholesterol-fed rabbits, dramatically inhibited the extent of aortic fatty streaks and lowered lipid deposition in the arterial wall and liver without modification of the plasma lipid levels.

Platelet interaction with vessel wall and collagen in pigs with homozygous von Willebrand's disease associated with abnormal collagen aggregation

A subgroup of pigs with von Willebrand's disease from the Mayo Clinic stock shows abnormal platelet aggregation in response to collagen [vWD-Homo(-)], in contrast to the normal aggregation responses observed in the main colony of pigs with homozygous vWD [vWD-Homo(+)]. This subgroup has been characterized at Mayo as a storage pool deficiency due to the reduced levels of ADP and Serotonin in the platelet dense granules. In the present studies, an ex-vivo perfusion chamber was utilized to investigate the deposition of 111In-labeled platelets on aortic subendothelium and collagen type I exposed to blood from vWD-Homo(-), vWD-Homo(+) and normal animals. Both non-anticoagulated and heparinized blood were exposed for wall shear rates ranging from 212 sec-1 to 3380 sec-1 and exposure times as long as 30 min. An enhanced decrease in platelet deposition in the vWD-Homo(-) animals was observed compared to vWD-Homo(+) animals. The decrease was observed primarily at the higher shear rates and was more pronounced in the absence of heparin and on the collagenous substrate. Thus, the abnormality in collagen-induced aggregation, which has been characterized as a storage-pool type defect, results in a decreased platelet deposition compared with that produced by severe vWD alone.

Electrical aggregometry in whole blood from human, pig and rabbit

The objective of this study was to characterize and standardize whole blood electrical aggregometry (WBEA) in the pig and rabbit, animal models extensively used in atherosclerosis research, and to compare their platelet response with that of man. Platelet aggregation was studied in blood (WBEA) and platelet rich plasma (optical aggregometry, OA). Dose response curves were obtained for ADP and collagen. The effect of hematocrit on WBEA was also evaluated. Aggregation with ADP and collagen using WBEA was more extensive with human than with pig or rabbit platelets. OA revealed similar differences among species but the time to reach maximal aggregation was markedly shorter. Using WBEA, the extent of aggregation was inversely related to the hematocrit. We conclude that WBEA is a useful technique that may be of particular importance in situations where hyperlipidemic plasma prevents the use of OA, as occurs in some atherosclerosis research animal models.

Influence of arterial damage and wall shear rate on platelet deposition. Ex vivo study in a swine model

To study the influence of blood flow on platelet interaction with selected biological surfaces, we have developed an ex vivo perfusion chamber system. In the present experiments, deendothelialized pig aorta and collagen Type I bundles from Achilles tendon were exposed to either native or heparinized pig blood for periods of time ranging from 1 to 30 minutes, and for flow rates corresponding to wall shear rates of 106 to 3380 sec-1. On the deendothelialized vessel wall, platelet deposition increased with both exposure time and wall shear rate, reaching a maximum value between 5 and 10 minutes of perfusion. At high shear rates and long exposure time (over 10 minutes), platelet deposition decreased from maximum values, indicating that some platelets were embolized by the flow. Ultrastructure analysis of the specimens showed platelet activation, spreading, and degranulation. Collagen induced a progressive accumulation of platelets following a power type curve of aggregate growth with exposure time without reaching a saturation level, even after long perfusion times (30 minutes) and high wall shear rates (3380 sec-1). In conclusion, the reactivity of the exposed materials and the local shear rate, defined by the blood flow and the patent luminal cross section, regulate platelet deposition to injured vascular wall.