Swine barn dust stimulates CCL9 expression in mouse monocytes through PKC-delta activation.

Exposure to organic barn dusts has been shown to cause numerous lung problems to chronically exposed animal barn workers. Bacterial components in these dusts trigger innate immunity in the lungs that we are still trying to fully characterize. CCL9/MIP-1γ is constitutively expressed in high quantities in the mouse circulation, but at much lower levels in the lungs where it is inducible under certain circumstances. We show here that extracts from hog barn dusts (HDE) are capable of inducing significant increases of CCL9 mRNA and protein in RAW267.4 monocytic cells as well as in mouse lungs. We further show that incubation of CCL9 with HDE results in cleavage of CCL9, which others have shown to increase chemotactic signaling potential. Endotoxin and proteoglycan were determined to be the likely causes of this increase. We additionally present evidence for a role of PKC-delta in this activation. Addition of purified CCL9 protein to HDE treated cell culture resulted in a small, but significant reduction in KC production, suggesting a possible regulatory role for the chemokine.

Epistatic effect of TLR-1, -6 and -10 polymorphisms on organic dust-mediated cytokine response.

Exposure to organic dust from agricultural environments is associated with inflammatory respiratory conditions. The putative causal agents in organic dust include viral, microbial and fungal components, which are recognized by the family of Toll-like receptors (TLRs) and drive host innate and adaptive responses. Our aim in this study was to determine whether responsiveness to organic dust among agricultural workers was dependent on polymorphisms in the TLR10-TLR1-TLR6 gene cluster. We stimulated whole blood from 509 agricultural workers with organic dust, triacyl lipopeptide N-palmitoyl-S-dipalmitoylglyceryl Cys-Ser-(Lys)4 (Pam3CSK4) and the diacyl-lipopeptide peptidoglycan. Several of the tagging polymorphisms and haplotypes conferred hyper-responsiveness to organic dust with an increase in interleukin-6 (IL-6; P<0.005), but not tumor necrosis factor-α (TNF-α), secretion. We conclude that genetic variation in the TLR10-TLR1-TLR6 gene cluster mediates responsiveness to organic dust, but indicates different signaling pathways for IL-6 and TNF-α. These studies provide new insight into the role of the TLR10-TLR1-TLR6 gene cluster and the innate immune response to organic dust.

Effect of elevated carbon dioxide on bronchial epithelial innate immune receptor response to organic dust from swine confinement barns.

Hypercapnia is known to have immunoregulatory effects within the lung. Cell culture systems demonstrate this in both macrophages and alveolar cell lines, suggesting that the alveoli are affected by changes in CO2 levels. We hypothesized that hypercapnia would also modulate human bronchial epithelial cell immune responses. Innate immune responses to Pam3CSK4 (TLR2 ligand), LPS (TLR4 ligand) and a complex innate immune stimulus, an extract from the organic dust of swine confinement barns (barn dust extract or BDE), were tested in a human bronchial epithelial cell line, BEAS-2B. Both TLR ligands showed a decrease in IL-6 and IL-8 production, and an increase in MCP-1 in response to elevated CO2 indicating an enhancement in cytokine production to hypercapnia. This change was not reflected in expression levels of TLR receptor RNA which remained unchanged in response to elevated CO2. Interestingly, barn dust showed an increase in IL-6, IL-8 and MCP-1 response at 9% CO2, suggesting that elevated CO2 exerts different effects on different stimuli. Our results show that airway epithelial cell immune responses to barn dust respond differently to hypercapnic conditions than individual TLR ligands.

Aging causes a slowing in ciliary beat frequency, mediated by PKCε.

The elderly are at much higher risk for developing pneumonia than younger individuals. Pneumonia is a leading cause of death and is the third most common reason for hospitalization in the elderly. One reason that elderly people may be more susceptible to pneumonia is a breakdown in the lung's first line of defense, mucociliary clearance. Cilia beat in a coordinated manner to propel out invading microorganisms and particles. Ciliary beat frequency (CBF) is known to slow with aging, however, little is known about the mechanism(s) involved. We compared the CBF in BALB/c and C57BL/6 mice aged 2, 12, and 24 mo and found that CBF diminishes with age. Cilia in the mice at age 12 and 24 mo retained their ability to be stimulated by the ß2 agonist procaterol. To help determine the mechanism of ciliary slowing, we measured protein kinase C alpha and epsilon (PKCα and PKCε) activity. There were no activity differences in PKCα between the mice aged 2, 12, or 24 mo. However, we demonstrated a significantly higher PKCε activity in the mice at 12 and 24 mo than the in the mice 2 mo of age. The increase in activity is likely due to a nearly threefold increase in PKCε protein in the lung during aging. To strengthen the connection between activation of PKCε and ciliary slowing, we treated tracheas of mice at 2 mo with the PKCε agonist 8-[2-(2-pentylcyclopropylmethyl)-cyclopropyl]-octanoic acid (DCP-LA). We noted a similar decrease in baseline CBF, and the cilia remained sensitive to stimulation with ß2 agonists. The mechanisms for the slowing of baseline CBF have not been previously determined. In this mouse model of aging we were able to show that decreases in CBF are related to an increase in PKCε activity.

Asymmetric dimethylarginine blocks nitric oxide-mediated alcohol-stimulated cilia beating.

The airway epithelium is exposed to alcohol during drinking through direct exhalation of volatized ethanol from the bronchial circulation. Alcohol exposure leads to a rapid increase in the cilia beat frequency (CBF) of bronchial epithelial cells followed by a chronic desensitization of cilia stimulatory responses. This effect is governed in part by the nitric oxide regulation of cyclic guanosine and adenosine monophosphate-dependent protein kinases (PKG and PKA) and is not fully understood. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, is implicated in the pathogenesis of several pulmonary disorders. We hypothesized that the inhibition of nitric oxide synthase by ADMA blocks alcohol-stimulated increases in CBF. To test this hypothesis, ciliated primary bovine bronchial epithelial cells (BBEC) were preincubated with ADMA (100 µM) and stimulated with 100 mM ethanol. CBF was measured and PKA assayed. By 1 hr, ethanol activated PKA, resulting in elevated CBF. Both alcohol-induced PKA activation and CBF were inhibited in the presence of ADMA. ADMA alone had no effect on PKA activity or CBF. Using a mouse model overexpressing the ADMA-degrading enzyme, dimethylarginine dimethylaminohydrolase (DDAH), we examined PKA and CBF in precision-cut mouse lung slices. Alcohol-stimulated increases in lung slice PKA and CBF were temporally enhanced in the DDAH mice versus control mice.

Proposal of a 2-tier histologic grading system for canine cutaneous mast cell tumors to more accurately predict biological behavior.

Currently, prognostic and therapeutic determinations for canine cutaneous mast cell tumors (MCTs) are primarily based on histologic grade. However, the use of different grading systems by veterinary pathologists and institutional modifications make the prognostic value of histologic grading highly questionable. To evaluate the consistency of microscopic grading among veterinary pathologists and the prognostic significance of the Patnaik grading system, 95 cutaneous MCTs from 95 dogs were graded in a blinded study by 28 veterinary pathologists from 16 institutions. Concordance among veterinary pathologists was 75% for the diagnosis of grade 3 MCTs and less than 64% for the diagnosis of grade 1 and 2 MCTs. To improve concordance among pathologists and to provide better prognostic significance, a 2-tier histologic grading system was devised. The diagnosis of high-grade MCTs is based on the presence of any one of the following criteria: at least 7 mitotic figures in 10 high-power fields (hpf); at least 3 multinucleated (3 or more nuclei) cells in 10 hpf; at least 3 bizarre nuclei in 10 hpf; karyomegaly (ie, nuclear diameters of at least 10% of neoplastic cells vary by at least two-fold). Fields with the highest mitotic activity or with the highest degree of anisokaryosis were selected to assess the different parameters. According to the novel grading system, high-grade MCTs were significantly associated with shorter time to metastasis or new tumor development, and with shorter survival time. The median survival time was less than 4 months for high-grade MCTs but more than 2 years for low-grade MCTs.

Toll-like receptor 2 is upregulated by hog confinement dust in an IL-6-dependent manner in the airway epithelium.

Hog confinement workers are at high risk to develop chronic bronchitis as a result of their exposure to organic dust. Chronic bronchitis is characterized by inflammatory changes of the airway epithelium. A key mediator in inflammation is Toll-like receptor 2 (TLR2). We investigated the role of TLR2 in pulmonary inflammation induced by hog confinement dust. Normal human bronchial epithelial cells (NHBE) were grown in culture and exposed to hog confinement dust extract. Hog confinement dust upregulated airway epithelial cell TLR2 mRNA in a concentration- and time-dependent manner using real-time PCR. There was a similar increase in TLR2 protein at 48 h as shown by Western blot. TLR2 was upregulated on the surface of airway epithelial cells as shown by flow cytometry. A similar upregulation of pulmonary TLR2 mRNA and protein was shown in a murine model of hog confinement dust exposure. Hog confinement dust is known to stimulate epithelial cells to produce IL-6. To determine whether TLR2 expression was being regulated by IL-6, the production of IL-6 was blocked using an IL-6-neutralizing antibody. This resulted in attenuation of the dust-induced upregulation of TLR2. To further demonstrate the importance of IL-6 in the regulation of TLR2, NHBE were directly stimulated with recombinant human IL-6. IL-6 alone was able to upregulate TLR2 in airway epithelial cells. Hog confinement dust upregulates TLR2 in the airway epithelium through an IL-6-dependent mechanism.

On the dual structure of the auditory brainstem response in dogs.

OBJECTIVE: To use the over-complete discrete wavelet transform (OCDWT) to further examine the dual structure of auditory brainstem response (ABR) in the dog. METHODS: ABR waveforms recorded from 20 adult dogs at supra-threshold (90 and 70dBnHL) and threshold (0-15dBSL) levels were decomposed using a six level OCDWT and reconstructed at individual scales (frequency ranges) A6 (0-391Hz), D6 (391-781Hz), and D5 (781-1563Hz). RESULTS: At supra-threshold stimulus levels, the A6 scale (0-391Hz) showed a large amplitude waveform with its prominent wave corresponding in latency with ABR waves II/III; the D6 scale (391-781Hz) showed a small amplitude waveform with its first four waves corresponding in latency to ABR waves I, II/III, V, and VI; and the D5 scale (781-1563Hz) showed a large amplitude, multiple peaked waveform with its first six waves corresponding in latency to ABR waves I, II, III, IV, V, and VI. At threshold stimulus levels (0-15dBSL), the A6 scale (0-391Hz) continued to show a relatively large amplitude waveform, but both the D6 and D5 scales (391-781 and 781-1563Hz, respectively) now showed relatively small amplitude waveforms. CONCLUSIONS: A dual structure exists within the ABR of the dog, but its relative structure changes with stimulus level. SIGNIFICANCE: The ABR in the dog differs from that in the human both in the relative contributions made by its different frequency components, and the way these components change with stimulus level.

Supplementation of 1% L-glutamine to milk replacer does not overcome the growth depression in calves caused by soy protein concentrate.

Glutamine, an important fuel and biosynthetic precursor in intestinal epithelial cells, helps maintain intestinal integrity and function when supplemented to the diet of many species. The hypothesis tested here was that glutamine supplementation would overcome the decreased average daily gain (ADG) and altered intestinal morphology caused by milk replacer containing soy protein concentrate (SPC). Holstein calves (9 male and 1 freemartin female per treatment) were assigned to diets of 1) all-milk-protein (from whey proteins) milk replacer, 2) milk replacer with 60% milk protein replacement from SPC, and 3) SPC milk replacer as in diet 2 plus 1% (dry basis) l-glutamine. Milk replacers were reconstituted to 12.5% solids and were fed at 10% of body weight from d 3 to 10 of age, and at 12% of body weight (adjusted weekly) from d 10 through 4 wk of age. No dry feed (starter) was fed, but water was freely available. Glutamine was added at each feeding to reconstituted milk replacer. Five calves from each treatment were slaughtered at the end of wk 4 for measurements of intestinal morphology. The ADG was greater for calves fed the all-milk control than for those fed SPC; glutamine did not improve ADG (0.344, 0.281, and 0.282 kg/d for diets 1 to 3, respectively). Intake of protein was adequate for all groups and did not explain the lower growth for calves fed SPC. Villus height and crypt depth did not differ among treatments in the duodenum. In the jejunum, villus height (713, 506, and 464 mum, for diets 1 to 3, respectively) and crypt depth (300, 209, and 229 mum, respectively) were greater for calves fed all milk protein than for either SPC group. In the ileum, villus height was greater for calves fed all milk than for either soy group (532, 458, and 456 mum), whereas crypt depth tended to be greater (352, 301, and 383 mum for diets 1 to 3, respectively), and the villus to crypt ratio was lower for calves supplemented with glutamine than for those fed SPC alone. Urea N concentration in plasma was greater for calves supplemented with glutamine than for those fed SPC alone, indicating that glutamine was at least partially catabolized. Supplemental l-glutamine did not improve growth or intestinal morphology of calves fed milk replacer containing SPC.

Molecular and genetic analyses of geographic variation in isolates of Phoma macrostoma used for biological weed control.

Molecular and genetic approaches were used to evaluate the genetic relatedness among isolates of the fungus Phoma macrostoma Montagne originating from Canada and Europe and to other species in the genus Phoma. Distinct differences were observed in genetic variation among nine species of the genus Phoma. Randomly amplified polymorphic DNA (RAPD) revealed the presence of intraspecific genetic variation among the isolates of P. macrostoma, with the isolates being used for biological weed control being distributed in a distinct phylogenetic cluster. Additional variation within the biocontrol isolate cluster in P. macrostoma was revealed by pulsed field gel electrophoresis (PFGE), which showed that biocontrol isolates generated two different chromosomal profiles, however the profiles did not relate to their Canadian ecozone origin. Mating studies showed that biocontrol isolates of P. macrostoma from Canada did not produce sexual reproductive structures and were incapable of crossing. These studies also confirmed that no obvious differentiation exists among the biocontrol isolates of P. macrostoma from Canadian Ecozones 3 and 4.

Cervical spinal cord compression and the Hoffmann sign.

Little information exists about the ability of the Hoffmann sign to predict cervical spinal cord compression. The objective of this study was to determine the correlation between the Hoffmann sign and cervical spinal cord compression in a consecutive series of patients seen by a single spine surgeon. All new patients with complaints related to their cervical spine were included. Hoffmann sign was elicited by flicking the nail of the middle finger. Any flexion of the ipsilateral thumb and/or index finger was considered positive. All imaging studies were reviewed for spinal cord compression. Cord compression was defined as flattening of the AP diameter of the spinal cord coexisting with obliteration of CSF around the cord compared to normal levels. Of 165 patients, 124 patients had imaging of their spinal canal. Review by the spine surgeon found sensitivity of the Hoffmann sign relative to cord compression was 58%, specificity 78%, positive predictive value 62%, negative predictive value 75%. 49 studies were also read by a "blinded" neuroradiologist, the sensitivity was 33%, specificity 59%, positive predictive value, 26%, negative predictive value 67%. Although attractive as a simple method of screening for cervical spinal cord compression, the Hoffmann sign, in the absence of other clinical findings, is not in our experience a reliable test.

Progression of an orbital T-cell rich B-cell lymphoma to a B-cell lymphoma in a dog.

An 11-year-old Shetland Sheepdog was presented for exophthalmos caused by a locally extensive, poorly defined mass located behind the right eye. The primary orbital mass was identified by light microscopy and immunohistochemistry as a T-cell rich B-cell lymphoma (TCRBCL) composed predominantly of BLA.36-positive large neoplastic lymphoid cells admixed with fewer CD3- and CD79a-positive small lymphocytes. The dog was treated for lymphoma, but 6 months after presentation it was euthanatized for suspected hepatic and gastrointestinal metastasis. Gross findings revealed an enlarged liver with multiple well-demarcated, randomly distributed 0.1-1.5-cm white nodules, five firm white submucosal jejunal nodules, and ileocecal, mediastinal, and hilar lymphadenopathy. Metastatic liver lesions consisted of sheets of monomorphic large neoplastic lymphoid cells that effaced and expanded portal and centrilobular zones. These cells were morphologically similar to the large neoplastic cells of the original orbital tumor and were CD3-negative and variably BLA.36-positive, consistent with B-cell lineage. Similar cells comprised the jejunal nodules and effaced the lymph nodes. The progression of TCRBCL to a diffuse B-cell lymphoma in this case is consistent with reported human cases and has not been previously reported in the dog.

Identification of epididymal stones in diverse rooster populations.

The epididymal region of the male reproductive tract is essential for sperm maturation, and dysfunction of this region results in infertility. Adult roosters have been observed to develop epididymal stones and consequently have reduced fertility. Efferent ductule cysts were first observed in White Leghorn roosters ages 18 to 26 wk. By 26 wk of age, the cysts had become solid, irregularly shaped, yellow-green stones primarily containing calcium (48%). The number and size of stones (9 to 160 microm, largest diameter) increased with age in affected males. Incidence ranged from 0 to 94% within rooster flocks surveyed. Stones have also been observed in broiler breeder roosters. Histological analysis of Leghorn and broiler breeder reproductive tracts revealed chronic inflammation with abundant interstitial mononuclear cell infiltrates. The normal, highly folded structure of efferent ductules was replaced by a thin, eroded epithelial layer with few luminal sperm. Abnormal areas were found interspersed with normal areas of epithelium. Broiler breeder male fertility trials demonstrated that birds with stones compared with normal males had reduced fertility following both natural mating (24.8+/-10.5% vs. 66.1+/-7.2%) and artificial insemination (47.8+/-16% vs. 82.0+/-6%). At 62 wk of age, testis weight (14.2+/-1.4 g vs. 20.5+/-1.2 g), daily sperm production (8.1+/-1.3 x 10(8) vs. 12.3+/-0.8 x 10(8) sperm per testis per day), and circulating testosterone concentrations (0.9+/-0.3 vs. 2.6+/-0.4 ng/mL) were all significantly reduced in males with stones. In conclusion, we are reporting a new dysfunction of the rooster reproductive tract that affects diverse bird populations and decreases fertility.

Influence of Moisture and Temperature on Infection of Canada Thistle by Alternaria cirsinoxia.

Relative humidity (RH), temperature, continuous leaf wetness, and intermittent leaf wetness were evaluated for their influence on conidial germination, appressoria formation, and infection of Canada thistle by Alternaria cirsinoxia. Conidia germinated and formed appressoria at 98% RH, but required at least 100% RH, and preferably free water, to penetrate leaves. In free water, conidia germinated equally well at 10, 15, 20, 25, or 30°C. Appressoria formation and leaf penetration also occurred at all temperatures evaluated from 10 to 30°C, with the highest values at 20 to 25°C and 20°C, respectively. Conidia required 8 h of continuous leaf wetness to establish visible symptoms of infection on Canada thistle. Exposure of conidia of A. cirsinoxia to up to five intermittent leaf wetness cycles (30 min wet/30 min dry) reduced germination, appressoria formation, and leaf penetration, but conidia remained infective after all cycles. Exposure to cycles of 4 h dew/20 h dry was most detrimental to infection, compared with a 72 h dry period or cycles of 1 h dew/23 h wet or 2 h dew/22 h wet, indicating greater sensitivity of more fully germinated conidia to drying. Such nonspecific temperature requirements and survival during repeated intermittent leaf wetness periods are beneficial characteristics for a bioherbicide. However, high moisture requirements for infection may limit the potential of using A. cirsinoxia to control Canada thistle in the semi-arid prairie provinces of Canada.

Compliance with sulfonylureas in a health maintenance organization: a pharmacy record-based study.

OBJECTIVE: To determine which factors affect compliance with sulfonylureas in a population served by a health maintenance organization in Southern California. METHODS: Retrospective analysis of pharmacy records and healthcare utilization data for two years (April 1993-March 1995), and a survey mailed to patients. Patients treated with sulfonylureas were selected for analysis on the basis of their prescription profile. Compliance was measured from the pharmacy records as the proportion of days the patient was in possession of the prescribed medications. Patient compliance with sulfonylureas was modeled as a function of four clusters of determinants: patient-related attributes, drug regimen characteristics and complexity, health status and disease-related variables, and characteristics of the interaction with healthcare providers. RESULTS: 786 patients were identified for analysis (49.1% women, mean age 59 y). The mean compliance rate was 83% +/- 22% SD. Compliance was significantly positively related with age and self-reported level of medication-taking compliance at baseline. Factors shown to have an inverse relationship with compliance were treatment complexity, perception of general health, and being a newly treated patient (adjusted R2 for the final model = 0.148). CONCLUSIONS: Our results suggest that factors found to be associated with noncompliant behavior (e.g., being a newly treated patient, self-reported compliance, regimen complexity) can be assessed by physicians and pharmacists as a routine practice.

Mesh diagram cephalometric norms for Americans of African descent.

The aim of this study was to establish cephalometric norms for African-American males and females, to compare these measurements with the findings of Alexander's "Alabama analysis," and to construct mesh templates for various age groups. The sample we evaluated included 71 African-Americans, divided into four groups: girls (8 to 12 years), boys (8 to 12 years), adolescent females (13 to 20 years), and adolescent males (13 to 20 years). The subjects met the following criteria: (1) normal Class I dental and skeletal relationship with minimal crowding, (2) balanced facial profile, and (3) no history of orthodontic treatment. The cephalometric radiographs were traced by hand, and linear and angular measurements were averaged to establish a mean with which to locate the anatomic landmarks used in the mesh diagram. In this study the African-Americans differed significantly from white Americans with regard to dental, skeletal, and soft tissue parameters. On average, the African-American subjects displayed larger SNA and ANB angles, more proclined lower incisors, and a more acute interincisal angle than did the white sample. Measurements between our African-American group and that of Alexander's African-American group in the "Alabama analysis" were consistent.

Establishing private duty in a Medicare world.

The Balanced Budget Act of 1997 projects $16.2 billion in Medicare cuts over five years, which will force dramatic changes in the home care delivery system. Medicare agencies with a good public image and strong referral sources are in a strong market position to offer private-duty services. Agencies in a weak market position should immediately begin to diversify their services to succeed in this new environment. Private duty can be lucrative if agency management establishes efficient systems, maintains high standards, and thinks like entrepreneurs.

Aorto-iliac thrombosis in a foal.

A six-day-old Missouri foxtrotter colt was examined because it had had diarrhoea since it was 24 hours old. A diagnosis of colitis, septicaemia, and disruption of the arterial blood flow to the pelvic limbs was made on the basis of clinical and laboratory findings. Despite intensive medical therapy, the foal died 13 hours after being examined. Postmortem examination revealed diffuse fibrinous enteritis with lymphoid necrosis, multifocal fibrinonecrotic typhlocolitis, disseminated intravascular coagulation, and a large occluding thrombus at the aortic termination. The results of bacteriological culturing supported the diagnosis of septicaemia leading to activation of the clotting cascade, disseminated intravascular coagulation, aorto-iliac thrombosis and infarction of the pelvic limbs.

Factors affecting patient compliance with antihyperlipidemic medications in an HMO population.

OBJECTIVE: To identify factors that influence compliance in patients taking antihyperlipidemic medications. STUDY DESIGN: This was a retrospective cohort study in which computerized pharmacy records were used to estimate medication compliance in patients in a Health Maintenance Organization from 1993 to 1995. PATIENTS AND METHODS: Data on 772 patients on antihyperlipidemic medications were obtained from pharmacy and healthcare utilization claims and from a cross-sectional survey. The medication compliance ratio for each patient was calculated from the prescription profile. Patient compliance was modeled as a function of four clusters of determinants: patient characteristics, complexity of drug regimen, health status, and patient-provider interaction. Correlation between specific characteristics and compliance was estimated by logistic regressions. RESULTS: Approximately 37% of patients complied with at least 90% or more of their antihyperlipidemic medications. The following variables had a significant influence on compliance: female gender (odds ratio [OR], 0.64), baseline compliance (high: OR, 3.42; medium: OR, 1.86), perceived health status (SF-36 bodily pain score: OR, 1.02; SF-36 vitality score: OR, 0.97), comorbidity (OR, 0.90), and number of daily doses of antihyperlipidemic medications (OR, 0.60). CONCLUSIONS: The findings suggest that women, patients with comorbidities, patients reporting high SF-36 vitality scores, and patients with multiple doses of antihyperlipidemic medications are less likely to be compliant. Patients who self-report good compliance with previous medications are more likely to comply. This information may be used to target interventions at patients who are likely to be noncompliant with their medication regimens.

Effect of calcium channel blockade on skin blood flow in diabetic hypertension: a comparison of isradipine and atenolol.

In previous studies, using laser Doppler techniques, the authors have demonstrated a duration-dependent reduction in skin blood flow reserve at sites of nutritive (NUTR) perfusion that occurs in diabetes and correlates with the presence of diabetic retinopathy and proteinuria. They speculated that it might be possible to reverse this decrease in blood flow by using agents with peripheral vasodilating properties. They chose the calcium channel blocking agent isradipine as a prototype. As a contrast agent, they chose atenolol, which has an equivalent antihypertensive effect but minimal peripheral vasodilating properties. They studied 24 diabetic hypertensive patients in a randomized, two-way crossover design. They assigned patients randomly to one or the other active drug and titrated to a maximum tolerated maintenance dose. Skin blood flow was measured at the end of the titration and maintenance phases. Patients then entered a four-week washout period, followed by crossover to the alternative drug, and measurements were repeated. At baseline, the twenty-four-hour mean ambulatory systolic blood pressure was 150 +/- 2 mm Hg with a twenty-four-hour mean diastolic blood pressure of 93 +/- 1 mm Hg. Thermally stimulated skin blood flow reserve was about 50% lower in these patients as compared with an age-, sex-, and weight-matched group of 28 nondiabetic, nonhypertensive patients. There was no difference in skin blood flow between the two groups at basal skin temperature or at a controlled temperature of 35 degrees C. Both atenolol and isradipine successfully lowered blood pressure in the study patients. There was a slightly greater decrease in systolic blood pressure with isradipine and a greater decrease in heart rate with atenolol. Neither isradipine nor atenolol treatment affected skin blood flow values at the maximal 44 degrees C temperature. However, at basal skin temperature and at 35 degrees C, isradipine-treated patients had substantial increases in skin blood flow at NUTR sites. For example, skin blood flow at the knee at 35 degrees C with isradipine treatment was 3.1 +/- 0.4 mL/min/100 g compared with 1.1 +/- 0.2 with atenolol, 1.3 +/- 0.1 with placebo, and 0.9 +/- 0.1 for the nondiabetic controls (all P < 0.01). The authors found a twofold to threefold increase in basal skin blood flow at NUTR sites with isradipine treatment. This degree of increase is substantially greater than that previously demonstrated by their group using pentoxifylline. Locally reduced skin blood flow is a factor in promoting skin breakdown and delayed healing. Further study is needed to explore the possibility that isradipine treatment may enhance healing of diabetic skin ulcers.