Short-term effects of Whole-Body Vibration on clinical, cardiac, and ambulatory electrocardiographic (Holter) parameters of healthy younger and older adult male non-athletic crossbreed dogs

ABSTRACT This study investigated the effects of WBV in clinical, cardiac, and ambulatory electrocardiographic (Holter) parameters of healthy young and aged male non-athletic dogs. Fourteen dogs were divided into two groups of seven animals: Group I (GI) - young dogs (12.0 and 84.0 months old); Group II (GII) - aged dogs (above 84.0 months old). Dogs were submitted to a single session of WBV (frequencies of 30 and 50 Hz), for 15-min. Variations were identified in the thickness of the interventricular septum and thickness of the left ventricle-free wall values: GI < GII at 5-min before the session. The diameter of the left atrium values showed a difference: GI < GII at 5-min before and 1-min after the session; and a decrease in GII between 5-min before and 1 min after the WBV. Several ambulatory electrocardiography (Holter) parameters demonstrated significant differences between both groups and time-points. A single session of WBV at frequencies of 30 and 50 Hz during 15-min by using a vibrating platform that delivered a vortex wave circulation did not induce significant changes in clinical, cardiac, and ambulatory electrocardiographic (Holter) parameters in healthy young and aged dogs.

Short-term Heart Rate Variability Analysis in Healthy Dogs of Different Ages

Background: The modulation of heart rate by autonomic nervous system may be evaluated by the heart rate variability (HRV), which illustrates the fluctuations between RR intervals. To evaluate this analysis, the intervals between 2 QRS complexes are measured. In general, high HRV values are expected in healthy individuals; otherwise, low values are indicative of organism dysfunction. Studies conducted in healthy humans show that HRV suffers reduction with ageing and that there is autonomic immaturity in neonates. The aim of this study was to describe the characteristic pattern of cardiac autonomic behavior in healthy dogs in different age groups through short-term HRV analysis.Materials, Methods & Results: A total of 87 healthy dogs were studied. HRV was analyzed in time and frequency domain, using Holter and heart rate monitor. It was observed that puppies (below one year old) presented a lower parasympathetic predominance and, consequently, lower HRV values on time domain (SDNN, PNN50% e RMSSD) compared to the other 2 groups and on frequency domain (LF, HF and LF/HF) compared to the adult animals group (between 1 and 7-year-old), which presented higher HRV values when compared to the other groups. Elderly dogs (over 8-year-old) exhibited a natural tendency to decrease cardiac parasympathetic HRV indexes.Discussion: The use of the HRV method as a prognostic index and as an arrhythmogenic marker for various canine heart diseases presents interesting perspectives. However, before it may be employed for these purposes, a better understanding should be established regarding the physiological behavior of autonomic cardiac modulation in different age groups to serve as a basis for future analyses. This study observed that puppies presented higher values for HR and, therefore, shorter RR intervals than the other groups (adult and elderly dogs), what was observed on Holter and heart rate monitor methods (HRM). There were significant differences between puppies and the other 2 groups (adults and elderly) for all time-domain variables using both methods (Holter and HRM methods). SDNN was significantly lower in puppies compared to adults and elderly dogs. In addition, both RMSSD and PNN50%, which were more reliable over shorter periods of time, also presented means and medians that were significantly lower in puppies. Regarding frequency-domain HRV parameters observed on Holter method, these indexes were decreased on the elderly group compared to adult dogs, which is a possible effect of aging. Also, puppies revealed lower frequency-domain HRV parameters on both methods when compared to adult dogs. The influence of age on HRV is possibly related to the stage of development of an individual, starting at conception up to the maturity in relation to the mechanisms that cause variations in HR. There are studies in humans that suggest a gradual increase in parasympathetic activity during childhood, followed by a steady decrease as aging occur. The present study observed the same pattern in dogs. The balance between sympathetic and parasympathetic systems is influenced by age in dogs, which alters HRV values in the short-term. The HRV method´s analysis is relatively simple and non-invasive for assessing cardiac autonomic function; also, it is widely used in human medicine as a risk measure for sudden cardiac death. The 24-hour HRV analysis is highly challenging, as it is time-consuming, expensive, delays diagnosis, and has a large number of artifacts; in this way, standards for its short-term analysis were developed. Keywords: cardiology, autonomic nervous system, heart rate monitor, Holter.

Serum Cortisol and Clinical Response to a Single Session of Whole-Body Vibration in Healthy Adult Dogs

This study evaluated the serum cortisol response to a single session of whole-body vibration (WBV) in healthy adult dogs. Ten healthy adult medium dogs, females and males, aged between 24 and 48 months and with body weight between 10.1 and 17.9 kg were used. A single WBV session at a frequency of 30 Hz for 5 min (3.10 mm peak displacement, 11.16 m/s² peak acceleration, and 0.29 m/s velocity), then 50 Hz for 5 min (3.98 mm peak displacement, 39.75 m/s² peak acceleration, and 0.62 m/s velocity), and finishing with 30 Hz for 5 min (3.10 mm peak displacement, 11.16 m/s² peak acceleration, and 0.29 m/s velocity) was performed. Serum cortisol, heart and respiratory rate, and systolic blood pressure were evaluated at different time points: 1 min before WBV (1PRE) and 1 min (1POST), 60 min (60POST), and 360 min (360POST) after the WBV session. An increase (P = 0.0417) of the serum cortisol values was observed between 1PRE and 1POST and a decrease (P = 0.0417) between 1POST and 60POST and between 60POST and 360POST. However, the values remained within the reference range. The heart and respiratory rate and the systolic blood pressure remained unchanged. Our findings suggest that a single bout of WBV (5 min of 30 and 50 Hz) using a vibrating platform that delivered a vortex wave circulation does not modify the serum cortisol levels and clinical parameters of healthy adult dogs.

Comparison of Three Imaging Methods for the Evaluation of Osteoarthritis Induced by Cranial Cruciate Ligament Transection in Rabbits

Background:Osteoarthritis is a degenerative joint disease that affects specially cartilage, meniscus, and tendons. Ligaments, muscles, subchondral bone and synovium. This pathology is a common condition limiting the quality of life of patients. Imaging modalities have also been used for evaluation the progression of the osteoarthritis, or degenerative processes induced by acute injury. In order to use more accessible imaging modalities for experimentation, this study aimed to compare radiographic, computed tomography, and ultrasound findings in the evaluation of osteoarthritis induced by the cranial cruciate ligament transection model in rabbits.Materials, Methods & Results:Twenty-four male Norfolk rabbits aged approximately 5 months old were used. All rabbits were submitted to cranial cruciate ligament transection of the left stifle and evaluated 45 days after the surgery. The radiographic findings were subchondral bone sclerosis (33.33%); joint space narrowing (66%); presence of osteophytes at medial femoral condyle (4.16%), lateral femoral condyle (4.16%), medial fabela (20.83%), lateral fabela (8.33%) and sesamoid of the popliteal muscle (4.16%). No osteophytes were seen at medial and lateral tibial condyles. The tomographic computed findings were joint space narrowing (62.5%); presence of osteophytes at medial femoral condyle (75%), lateral femoral condyle (54.16%), medial fabela (66.66%), lateral fabela (37.5%), medial tibial condyle (75%), lateral tibial condyle (20.83%) and sesamoid of the popliteal muscle (37.5%). The ultrasound findings were synovial hypertrophy (95.83%); effusion in the suprapatellar recess (75%), distal tibial recess (16.66%) and cranial joint space (75%); changes (hyperechogenic foci and heterogeneity) of the lateral meniscus (50%) and medial meniscus (25%); increased thickness of the medial condyle (54.16%) and lateral condyle (45.83%); irregularity of the medial condyle (66.66%) and lateral condyle (58.33%); alterations of the patellar tendon (12.5%) and extensor ligament (effusion and increased echogenicity) (20.83%).Discussion: Osteoarthritis is a degenerative joint disease and is common condition which limiting the quality of life of patients. Many studies performed in rabbits have evaluated the development of osteoarthritis through post-mortem macroscopic or microscopic assessments. Imaging modalities have also been used for evaluation the progression of the osteoarthritis, or degenerative processes induced by acute injury. High quality radiographs are accurate in identifying structural changes resulted from osteoarthritis, but computed tomography allows earlier identification in relation to conventional radiography. The three imaging modalities were helpful to identify the osteoarthritis, but the findings were different and compatible with each analysis method. The computed tomographic detected a higher number of osteophytes than plain radiographs. Also, osteophytes did not visualized by radiographic examination, such as medial tibial condyle and lateral tibial condyle, were identified by computed tomography. In turn, the ultrasound examination enabled identification of lesions did not seen on radiographic and computed tomography examinations. Synovial hypertrophy and joint effusion had the highest percentage. In human patients, ultrasound examination has been used to assess hypertrophy and inflammation of the synovium due to osteoarthritis. In conclusion, computerized tomography images provided more information than plain X-ray images and can be complemented by ultrasound examination to identify osteoarthritis induced by cranial cruciate ligament transection in rabbits.Comparison of Three Imaging Methods for the Evaluation of Osteoarthritis Induced by Cranial Cruciate Ligament Transection in Rabbits

Effects of Whole-Body Vibration in Hematobiochemical and Hemogasometric Parameters in Adult and Elderly Healthy Dogs

Background: Whole-Body Vibration (WBV) consists of mechanical vibration stimuli produced that propagate throughout the body by increasing the gravitational load. The WBV can increase muscle mass in dogs with muscular atrophy. As Whole-body vibration (WBV) can be used as exercise modality with no impact on the joints, the present study aimed to evaluate the effects of single session of WBV in hematobiochemical and hemogasometric parameters in adult and elderly healthy dogs. Materials, Methods & Results: Fourteen clinically healthy, neutered crossbreed male dogs, non-athlete were selected. The dogs were divided into two groups of seven dogs, according to the age group: Group I - adult dogs (GI): age between 12.0 and 84.0 months old; Group II - elderly dogs (GII): age above 84.0 months old. All dogs were submitted to a single session WBV by using a vibrating platform that delivered a vortex wave circulation as mechanical vibration. The WBV protocol used was 30 Hz frequency (3.10 mm peak displacement; 11.16 m/s2 peak acceleration; 0.29 m/s velocity), then 50 Hz (3.98 mm peak displacement; 39.75 m/s2 peak acceleration; 0.62 m/s velocity), and lastly 30 Hz (3.10 mm peak displacement; 11.16 m/s2 peak acceleration; 0.29 m/s velocity) for 5-min between de frequencies. The hematobiochemical and hemagasometric parameters were evaluated at 1-min before the WBV session (1PRE), 1-min after the WBV session (1POST), 120-min (120POST) and 24 hours after the WBV session (24hPOST). The dogs accepted well the vibration stimulus, however, elderly dogs weighting above 30 kg were more likely to sit down with increased frequency from 30 to 50 Hz. No variations of food and water intakes and gastrointestinal changes were observed after the WBV session. Hemoglobin values showed significant decrease (P = 0.0312) between 1PRE and 1POST in elderly dogs. A significant decrease (P = 0.0453) was observed in alanine aminotransferase values between 120POST and 14hPOST in adult dogs. Creatinine values had a statically decrease (P = 0.0173) between 1PRE and 24hPOST in adult dogs. However, these values remained within the reference range for dogs. Discussion: According to the literature, there are no studies related to the effects of WBV in haematobiochemical and hemogasometric parameters in adult and elderly dogs. No deleterious effects regarding to a single session of WBV were observed, however harmful effects were observed in human patients. The elderly dogs with body mass above 30 kg tried to sit during the increased frequency from 30 to 50 Hz, which was associated with the pressure exerted in their paws. No significant differences were observed in erythrogram and leukogram parameters except for hemoglobin values. Significant decline was observed in hemoglobin values in adult Beagle dogs; and were associated with hemolysis. The significant decrease in alanine aminotransferase and creatinine values did not have clinical significance. No significant alterations were identified in hemogasometric parameters but slight increase in pH values was observed in horses subjected to a 60 km run, and was associated to the loss of Cl ions in sweat. The single session of WBV by using a vibrating platform that delivered a vortex wave circulation, at 30 and 50 Hz frequencies for 5 min did not induced significant changes in hematobiochemical and hemogasometric parameters in adults and elderly healthy dogs.

Acute Effects of Whole-Body Vibration on Dopplerfluxometry of the Common Carotid Artery Parameters among Adult and Elderly Non-Athletes Healthy Dogs

Background: Whole-Body Vibration (WBV) is an oscillatory mechanical stimulus spreading throughout the body and considered a type of physical exercise because of the activation of the cardiovascular, musculoskeletal, and neuroendocrine systems. It is a physical exercise modality since it promotes cardiovascular resistance, increase in muscular strength and neurosensitivity, and motor coordination improvement. For use of WBV as an exercise modality for dogs, it is necessary to evaluate the Dopplerfluxometry parameters of the common carotid artery in healthy dogs in order to perform a safe protocol without inducing any cerebral alteration. This study aimed to evaluate the acute effects of WBV on systolic peak velocity (SPV), resistivity (RI), and pulsatility index (PI) of the both common carotid artery among adults and elderly non-athletes healthy dog.Materials, Methods & Results: Fourteen clinically healthy, neutered crossbreed male dogs, non-athlete were divided into two groups of seven dogs, according to the age group: Group 1 (G1)- Adult dogs: age between 12 and 84 months; Group 2 (G2)- Elderly dogs: aged over 84 months. All dogs were submitted to sessions of WBV using the protocol of 30 Hz for 5 min, followed by an increase to 50 Hz for 5 more min and ending with 5 min at 30 Hz, without rest between the variation of the vibration frequency. The systolic peak velocity (SPV), resistivity (RI), and pulsatility index (PI) of the common carotid artery were assessed in two time-points: 5 min before the WBV sessions (5PRE) and 1 min after the WBV (1POS). No significant variations in the SPS, RI, and PI of both common carotid artery of the G1 and G2 were identified. The anatomic reference for the left and right common carotid artery was the right and left extern jugulars veins, which were identified by the venous blood vessel characteristics as endothelium type, and single-phase without systolic peaks wave. Discussion: In humans, WBV is indicated to muscle size and tone increase, therefore it is believed that this modality can present a beneficial result in dogs with muscular atrophy associated with orthopedic surgeries and in cases of osteoarthritis. Irreversible brain damage can be caused by a possible hemodynamic alteration in the common carotid arteries resulted from mechanical vibrations. Parkinson’s disease patients and individuals affected by strokes that went under acute sessions of WBV showed handshake reduction and better proprioception, respectively. The beneficial effect was observed in cervix opening in dogs with metritis. The behavior of sitting of the dogs over 30 kg during WBVsessions was associated with paraparesis. This result was present in medium-size non-athletic dogs weighing from 10.1 to 17.9 kg that went through WBV for 5 consecutive days, using the same vibrating platform. No signs of discomfort during a single session of 10 min of WBV (15 and 21 Hz) were observed in healthy adult horses.  Studies using mechanical vibrations on adult healthy dogs did not show significant variation RI of the renal artery. On the other hand, daily use of WBV for 5 days on dogs showed significant enhancement on RI of the femoral artery immediately after it. A single session of WBV (30 and 50 Hz did, for 15 min) do not produce undesirable effects on SPV, RI, and PI of both common carotid arteries in adult and elderly non-athletic healthy dogs.

Whole-Body Vibration Exercise on Hematology and Serum Biochemistry in Healthy Dogs

The present study aimed to evaluate the influence of whole-body vibration (WBV) exercise on hematology and serum biochemistry in healthy dogs. Ten intact beagle dogs, 3 females, and 7 males, with a mean age of 3 years, and mean body mass of 14.3kg, body condition score between 4.0/9 and 4.5/9 were evaluated. The WBV sessions were done with the dog standing up on all 4 feet on a vibrating platform. Daily session of 30Hz for 5 minutes, followed by 50Hz for 5 minutes and finishing with 30Hz for 5 minutes was accomplished for 5 days. The velocity and amplitude of the vibrating platform were 12-40m/s² and 1.7-2.5mm, respectively. Blood samples were collected, before and immediately after the WBV platform exercise session, and 1 and 6 hours after the end of each session for 5 days. In addition, blood samples were collected 24 hours and 48 hours after the last WBV platform exercise session. Complete blood count and serum biochemistry (alanine aminotransferase, aspartate aminotransferase, creatine kinase, blood urea nitrogen, creatinine, and serum total protein) were the data analyzed. The erythrocytes, hemoglobin, and packet cell volume values decreased, whereas the leukocytes, neutrophils, and eosinophils values increased after WBV platform exercise sessions; however, all values were within the reference range. Other hematological and serum biochemical parameters did not show important variations. In conclusion, the WBV exercise sessions attended for 5 consecutive days did not adversely affect the hematology and serum biochemistry of adult healthy dogs.

Scaling Relationships Among Heart Rate, Electrocardiography Parameters, and Body Weight

Although heart rate (HR) is one of the most important clinical parameters determined via physical examinations, little information is available on the normal HR in dogs, which may be related to the high variability of body weight (BW) in this species. HR is determined by the discharge rate of the sinus node, which is dependent on the autonomic nervous system and the release of catecholamines. The allometric relationship between BW and HR in different species has been described as inversely proportional; however, this relationship has been refuted. Certain authors have reported that the relationship between HR and BW in dogs is based on temperament as well as sympathetic autonomic stimulation of the sinus node in small breeds compared with large breeds. The aim of this study was to analyze the effects of weight, sex, age and temperament on the HR, heart rate variability and serum catecholamine (epinephrine and norepinephrine) levels in dogs. We evaluated 48 adult dogs of both sexes and various breeds and ages and divided the dogs into 5 BW groups: <5kg (n = 8), 5-10kg (n = 10), 10-25kg (n = 10), 25-45kg (n = 10), and >45kg (n = 10). The measured parameters were HR, breath rate (BR) and body temperature. We also performed an ambulatory electrocardiogram and electrocardiography (ECG) test for 24 hours (Holter monitor) and determined the serum levels of the catecholamines epinephrine and norepinephrine. We observed correlations between HR and sex; differences among the weight groups with respect to ECG variables and epinephrine levels; and differences among the temperament categories for certain clinical parameters, such as HR and BR. Age affected the R wave amplitude, and an allometric relationship was not observed between HR and BW in the dogs. Our results indicated that weight was associated with variations in the ECG variables; age and sex were associated with variations in HR; and temperament had a significant influence on the HR and BR of the dogs.

Abstract P634: The Influence Of Virtual Learning Environment On Therapy Adherence And On The White Coat Effect

Systemic arterial hypertension is a risk factor for cardiovascular diseases and has become a common public health problem. Health education associated with educational technology may be used to encourage patients’ adherence to treatment and enable them to adequately understand how harmful hypertension can be to health, thereby promoting their quality of life. OBJECTIVE: To evaluate the influence of a strategy in an individual orientation program using educational technology associated with virtual learning environment (VLE) of hypertension care on the reduction in the white coat effect and the improvement in blood pressure control to be promoted by a nurse in a hypertension unit in a government state hospital in São Paulo. METHODS AND MATERIALS:This was a randomized clinical education study conducted with two groups, the VLE group (study group, 10 patients) and the control group (16 patients). Both groups were interviewed 6 times by nurses during the 120-day follow-up at 20-day intervals. At baseline (randomization) and at the end of the study, the patients took Spielberg’s State-Trait Anxiety Inventory (STAI), the Morisky test, and the WHOQOL, a quality of life instrument, and had their blood pressure taken (ambulatory blood pressure monitoring [ABPM]). Both groups had their blood pressure, weight, and abdominal circumference measured. Only the study group had remote access to the VLE. This consisted of 6 specific educational modules, each released according to the encounter number. RESULTS: At baseline, there were no statistical differences between the two groups with respect to the sociodemographic and hemodynamic variables. At the end of the study, there was a significant statistical difference between the groups on the Morisky test (p=0.001) and on the WHOQOL with respect to domain 3 social (p=0.001). There was no statistical difference with respect to the white coat effect between the groups. Nor was there any statistical difference between the groups with respect to the association of the anxiety degree measured by STAI and the white coat effect.CONCLUSION: In light of the results, our strategy improved the quality of life in the social domain and changed the adherence behavior of the study group in relation to the forgetfulness of medication schedules.

The effect of paramagnetic contrast in choline peak in patients with glioblastoma multiforme might not be significant

BACKGROUND AND PURPOSE

(1)H-MR spectroscopy is a useful tool in brain tumor evaluation. A critical point in obtaining representative spectra is the correct voxel positioning, which can be more accurate after Gd administration. Some experimental data suggested that Gd could cause Cho signal loss. Our aim was to evaluate the effect of Gd in the Cho peak area and width in patients with GBM.

MATERIALS AND METHODS

We performed multivoxel (1)H-MR spectroscopy before and after Gd administration in 18 patients with GBM. Quantification of Cho peak area and width in each voxel was completed, and the Cho mean and maximum values before and after Gd injection were calculated in the tumor and contralateral hemisphere. Choline peak area and width values obtained before and after contrast were compared, considering as separate entities enhancing and nonenhancing tumoral voxels and the contralateral hemisphere.

RESULTS

No statistically significant differences were found for the Cho peak area mean values in the tumoral voxels or contralaterally (P > .05). A tendency for an increase in the Cho peak width mean value was found in the tumoral enhancing voxels (P = .055). A statistically significant decrease was found for the mean value of the maximum Cho peak area in enhancing tumoral voxels (P = .020). No significant differences were found in the nonenhancing tumoral voxels or contralaterally (P > .05).

CONCLUSIONS

The injection of Gd before performing (1)H-MR spectroscopy might not significantly affect the Cho peak area in patients with GBM. The paramagnetic contrast seems to cause a different effect, depending on Gd enhancement.

Central and peripheral cardiovascular actions of adrenomedullin 5, a novel member of the calcitonin gene-related peptide family, in mammals

Adrenomedullin 5 (AM5) is a new member of the calcitonin gene-related peptide (CGRP) family identified in teleost fish. Although its presence was suggested in the genome database of mammals, molecular identity and biological function of AM5 have not been examined yet. In this study, we cloned a cDNA encoding AM5 in the pig and examined its cardiovascular and renal effects. Putative mature AM5 was localized in the middle of prohormone and had potential signals for intermolecular ring formation and C-terminal amidation. The AM5 gene was expressed most abundantly in the spleen and thymus. Several AM5 genes were newly identified in the database of mammals, which revealed that the AM5 gene exists in primates, carnivores, and undulates but could not be identified in rodents. In primates, nucleotide deletion occurred in the mature AM5 sequence in anthropoids (human and chimp) during transition from the rhesus monkey. Synthetic mature AM5 injected intravenously into rats induced dose-dependent decreases in arterial pressure at 0.1-1 nmol/kg without apparent changes in heart rate. The decrease was maximal in 1 min and AM5 was approximately half as potent as AM. AM5 did not cause significant changes in urine flow and urine Na+ concentration at any dose. In contrast to the peripheral vasodepressor action, AM5 injected into the cerebral ventricle dose-dependently increased arterial pressure and heart rate at 0.1-1 nmol. The increase reached maximum more quickly after AM5 (5 min) than AM (15-20 min). AM5 added to the culture cells expressing calcitonin receptor-like receptor (CLR) or calcitonin receptor (CTR) together with one of the receptor activity-modifying proteins (RAMPs), the combination of which forms major receptors for the CGRP family, did not induce appreciable increases in cAMP production in any combination, although AM increased it at 10(-)(10)-10(-)(9) M when added to the CLR and RAMP2/3 combination. These data indicate that AM5 seems to act on as yet unknown receptor(s) for AM5, other than CLR/CTR+RAMP, to exert central and peripheral cardiovascular actions in mammals.

Isolation and characterization of mammalian D-aspartyl endopeptidase

The accumulation of D-isomers of aspartic acid (D-Asp) in proteins during aging has been implicated in the pathogenesis of Alzheimer's disease (AD), cataracts and arteriosclerosis. Here, we identified a specific lactacystin-sensitive endopeptidase that cleaves the D-Asp-containing protein and named it D-aspartyl endopeptidase (DAEP). DAEP has a multi-complex structure (MW: 600 kDa) and is localized in the inner mitochondrial membrane. However, DAEP activity was not detected in E. coli, S. cerevisiae, and C. elegans. A specific inhibitor for DAEP, i-DAEP: (benzoyl-L-Arg-L-His-[D-Asp]-CH(2)Cl; MW: 563.01), was newly synthesized and inhibited DAEP activity (IC(50), 3 microM), a factor of ten greater than lactacystin on DAEP. On the other hand, i-DAEP did not inhibit either the 20S or 26S proteasome. And we identified succinate dehydrogenase and glutamate dehydrogenase 1 as components of DAEP by affinity label using biotinylated i-DAEP. In the long life span of mammals, DAEP may serve as a scavenger against accumulation of racemized proteins in aging. Insights into DAEP will provide the foundation for developing treatments of diseases, such as AD, in which accumulation of D-Asp-containing proteins are implicated.

Crystal structure of an elastase-specific inhibitor elafin complexed with porcine pancreatic elastase determined at 1.9 A resolution

The crystal structure of a stoichiometric complex between an elastase-specific inhibitor elafin and porcine pancreatic elastase (PPE) has been determined and refined to a crystallographic R-factor of 19.7% at 1.9 A resolution. The polypeptide chain of elafin has a planar spiral shape with an exposed external part and an internal core part which resembles both the crystal structure of human seminal plasma inhibitor (HUSI-1) [Grütter, M. G., Fendrich, G., Huber, R., & Bode, W. (1988) EMBO J. 7, 345-351] and the solution structure of Na+,K(+)-ATPase inhibitor (SPAI-1) revealed by NMR analysis [Kozaki, T., Kawakami, Y., Tachibana, S., Hatanaka, H., & Inagaki, F. (1994) Pept. Chem., 405-408]. The external region containing the primary binding loop is interconnected by four disulfide bonds to the internal part composed of a beta-sheet and a hairpin loop. The scissile peptide bond Ala24i(P1)-Met25i(P1') in the primary binding site is intact, and its carbonyl carbon is in van der Waals contact with O gamma of the active site Ser195 of PPE. The seven residues of Leu20i(P5)-Leu26i(P2') of the primary binding loop and the three residues of Ser48i, Cys49i, and Ala52i of the adjacent hairpin loop are in contact with PPE by hydrogen bonds and/or van der Waals interactions in a manner similar to that observed for other serine protease-inhibitor complexes. Electron densities of the N-terminal residues Ala1i-Ser10i which are not responsible for the elastase inhibitory activity were not visible, probably due to disordered conformation. The guanido group (N eta 1, N eta 2) of Arg61 in the complex interacts with S delta of Met25i(P1') by possible hydrogen bonds between N and S atoms, accompanying a large positional shift of the side chain of Arg61-(S1') between the complexed and free forms of PPE. The primary binding site is stabilized by hydrogen bonds between the guanido group (N eta 1, N eta 2) of Arg22i(P3) and the carbonyl group of Met25i(P1') across the scissile bond, as well as by a hydrogen bond between the amino group of Cys23i(P2) and the carbonyl group of Ser48i in the internal core. This intramolecular hydrogen bond network and the network of four disulfide bonds might play a significant role in stabilizing the conformation of the binding site for expressing the potent specific inhibitory activity.

Synthesis and conformational investigation of tandem repeat sequence in RNA polymerase II

The largest subunit of RNA polymerase II has a very interesting sequence in the C-terminus; that is, a tandem repeat sequence of Ser-Pro-Thr-Ser-Pro-Ser-Tyr consisted of proline residues and three kinds of residues having side-chain hydroxyl groups. Although lack of this tandem repeat is a lethal event in vivo, its functional role is unclear. The sequential polypeptide corresponding to this tandem repeat, poly(Ser-Pro-Thr-Ser-Pro-Ser-Tyr), was synthesized and its conformation was investigated by circular dichroism comparing to the monomeric heptapeptide. In addition, the theoretical conformational analysis based on the molecular mechanics was tried for the heptapeptide in the repeating unit and the periodic polyheptapeptide corresponding to the tandem repeat sequence. These results suggested the possibility that the tandem repeat contains a kind of super conformation composed of the repetitive turn structure in the native state. The characteristic repetitive turn structure would be the key of its function mechanism.

Crystallization of a complex between an elastase-specific inhibitor elafin and porcine pancreatic elastase

A complex between synthetic elafin, an elastase-specific inhibitor, and porcine pancreatic elastase was crystallized using 2-methyl-2,4-pentanediol as precipitant. The crystals belong to the monoclinic space group P2(1) with cell parameters a = 37.91 A, b = 73.32 A, c = 48.92 A, beta = 105.4 degrees, and one complex molecule in the asymmetric unit. The crystals diffract X-rays to 1.9 A resolution and are suitable for crystallographic structure analysis.

Synthesis and structure-activity relationships of elafin, an elastase-specific inhibitor

Elafin, an elastase-specific inhibitor isolated from human skin, and its related peptides were synthesized by the solution procedure, and their inhibitory activities were measured against various enzymes. During the oxidative folding reactions of the reduced peptides, the ratio of the active product to the inactive product was varied by changing the concentration of guanidine HCl and the amount of redox reagents. The disulfide structures of fully active synthetic elafin and the inactive product were determined by amino acid analysis, gas-phase sequencing and mass spectrometry of their proteolytic fragments. The relationship between structure and inhibitory activities and/or the folding reaction was examined and the amino terminal part of the elafin molecule was found to have a great influence on the folding reactions, but not on the inhibitory activities.

Structure-activity relationship of endothelin: importance of charged groups

Endothelin (ET)-related peptides including ET-1 (1-39) were synthesized, and their constricting activity in rat pulmonary artery rings and pressor activity in unanesthetized rat were measured to elucidate their structure-activity relationship. The vasoconstrictor activities of ET-2, ET-3 and sarafotoxin S6b were one-half, one-60th and one-third that of ET-1, respectively. Such differences in biological activities should mainly arise from sequence heterogeneity at the N-terminal portion, especially at positions 4 to 7. All of the blocked ETs at the amino or carboxyl termini showed greatly decreased activities. A monocyclic analog, in which Cys3 and Cys11 were replaced by Ala, showed one-third the activity of ET-1; however, its deamino dicarba analog was almost completely inactive. Significant activities were retained even with replacement of amino acids at positions Ser4, Ser5, Leu6, Met7, Lys9, Tyr13, and Trp21 by Ala, Ala, Gly, Met(0), Leu, Phe, and Tyr or Phe, respectively. On the other hand, replacement of Asp8, Glu10 and Phe14 by Asn, Gln and Ala, respectively, resulted in complete loss of the biological activity. These results indicated that two disulfide bonds in ET molecule were not essential for the expression of vasoconstricting activity. Both terminal amino and carboxyl groups, carboxyl groups of Asp8 and Glu10, and the aromatic group of Phe14 seemed to be contributing, more or less, to the expression of the biological activities.