Branched-chain amino acids: Abundance of their transporters and metabolizing enzymes in adipose tissue, skeletal muscle, and liver of dairy cows at high or normal body condition.

Branched-chain amino acids (BCAA) are major components of milk protein and important precursors for nonessential AA. Thus, the BCAA transport and break-down play a key role in the metabolic adaptation to the high nutrient demands in lactation. However, in monogastrics, increased BCAA levels have been linked with obesity and certain metabolic disorders such as impaired insulin sensitivity. Our objective was to study the effect of over-conditioning at calving on plasma BCAA levels as well as the tissue abundance of the most relevant BCAA transporters and degrading enzymes in dairy cows during late pregnancy and early lactation. Thirty-eight Holstein cows were allocated 15 wk antepartum to either a normal- (NBCS) or over-conditioned (HBCS) group, receiving 6.8 or 7.2 MJ of NEL/kg of DM, respectively, during late lactation to reach the targeted differences in body condition score (BCS) and back fat thickness (BFT; NBCS: BCS <3.5, BFT <1.2 cm; HBCS: BCS >3.75, BFT >1.4 cm) until dry-off. During the dry period and next lactation, cows were fed the same diets, whereby differences in BCS and BFT were maintained: prepartum means were 3.16 ± 0.06 and 1.03 ± 0.07 cm (NBCS) vs. 3.77 ± 0.08 and 1.89 ± 0.11 cm (HBCS), postpartum means were 2.89 ± 0.06 and 0.81 ± 0.05 cm (NBCS) vs. 3.30 ± 0.06 and 1.38 ± 0.08 cm (HBCS). Blood and biopsies from liver, semitendinosus muscle, and subcutaneous adipose tissue (scAT) were sampled at d 49 antepartum, 3, 21, and 84 postpartum. Free BCAA were analyzed and the mRNA abundance of solute carrier family 1 member 5 (SLC1A5), SLC7A5, and SLC38A2 as well as branched-chain aminotransferase 2 (BCAT2), branched-chain α-keto acid dehydrogenase E1α (BCKDHA), and branched-chain α-keto acid dehydrogenase E1ß (BCKDHB) as well as the protein abundance of BCKDHA were assessed. Concentrations of all BCAA changed with time, most markedly in HBCS cows, with a nadir around calving. Apart from Ile, neither individual nor total BCAA differed between groups. The HBCS group had greater BCKDHA mRNA as well as higher prepartum BCKDHA protein abundance in scAT than NBCS cows, pointing to a greater oxidative capacity for the irreversible degradation of BCAA transamination products in scAT of over-conditioned cows. Prepartum hepatic BCKDHA protein abundance was lower in HBCS than in NBCS cows. In both groups, SLC1A5, SLC7A5, and BCAT2 mRNA were most abundant in scAT, whereas SLC38A2 was higher in scAT and muscle compared with liver, and BCKDHA and BCKDHB mRNA were greatest in liver and muscle, respectively. Our results indicate that scAT may be a major site of BCAA uptake and initial catabolism, with the former, however, being independent of BCS and time relative to calving in dairy cows.

Changes in tissue abundance and activity of enzymes related to branched-chain amino acid catabolism in dairy cows during early lactation.

Branched-chain α-keto acid dehydrogenase (BCKDH) complex catalyzes the irreversible oxidative decarboxylation of branched-chain α-keto acids. This reaction is considered as the rate-limiting step in the overall branched-chain amino acid (BCAA) catabolic pathway in mammals. For characterizing the potential enzymatic involvement of liver, skeletal muscle, adipose tissue (AT), and mammary gland (MG) in BCAA metabolism during early lactation, tissue and blood samples were examined on d 1, 42, and 105 after parturition from 25 primiparous Holstein cows. Serum BCAA profiles were analyzed and the mRNA and protein abundance as well as the activity in the different tissues were assessed for the BCAA catabolic enzymes, partly for the branched-chain aminotransferase and completely for BCKDH. Total BCAA concentration in serum was lowest on d 1 after parturition and increased thereafter to a steady level for the duration of the experiment. Pronounced differences between the tissues were observed at all molecular levels. The mRNA abundance of the mitochondrial isoform of branched-chain aminotransferase (BCATm) was greatest in AT as compared with the other tissues studied, indicating that AT might be an important contributor in the initiation of BCAA catabolism in dairy cows. From the different subunits of the BCKDH E1 component, only the mRNA for the ß polypeptide (BCKDHB), not for the α polypeptide (BCKDHA), was elevated in liver. The BCKDHA mRNA abundance was similar across all tissues except muscle, which tended to lower values. Highest BCKDHA protein abundance was observed in both liver and MG, whereas BCKDHB protein was detectable in these tissues but could not be quantified. Adipose tissue and muscle only displayed abundance of the α subunit, with muscle having the lowest BCKDHA protein of all tissues. We found similarities in protein abundance for both BCKDH E1 subunits in liver and MG; however, the corresponding overall BCKDH enzyme activity was 7-fold greater in liver compared with MG, allowing for hepatic oxidation of BCAA transamination products. Reduced BCKDH activity in MG associated with no measurable activity in AT and muscle may favor sparing of BCAA for the synthesis of the different milk components, including nonessential AA. Deviating from previously published data on BCAA net fluxes and isotopic tracer studies in ruminants, our observed results might in part be due to complex counter-regulatory mechanisms during early lactation.

Comparison of performance and metabolism from late pregnancy to early lactation in dairy cows with elevated v. normal body condition at dry-off.

Excessive mobilization of body reserves during the transition from pregnancy to lactation imposes a risk for metabolic diseases on dairy cows. We aimed to establish an experimental model for high v. normal mobilization and herein characterized performance, metabolic and endocrine changes from 7 weeks antepartum (a.p.) to 12 weeks postpartum (p.p.). Fifteen weeks a.p., 38 pregnant multiparous Holstein cows were allocated to two groups that were fed differently to reach either high or normal body condition scores (HBCS: 7.2 NEL MJ/kg dry matter (DM); NBCS: 6.8 NEL MJ/kg DM) at dry-off. Allocation was also based on differences in body condition score (BCS) in the previous and the ongoing lactation that was further promoted by feeding to reach the targeted BCS and back fat thickness (BFT) at dry-off (HBCS: >3.75 and >1.4 cm; NBCS: <3.5 and <1.2 cm). Thereafter, both groups were fed identical diets. Blood samples were drawn weekly from 7 weeks a.p. to 12 weeks p.p. to assess the serum concentrations of metabolites and hormones. The HBCS cows had greater BCS, BFT and BW than the NBCS cows throughout the study and lost more than twice as much BFT during the first 7 weeks p.p. compared with NCBS. Milk yield and composition were not different between groups, except that lactose concentrations were greater in NBSC than in HBCS. Feed intake was also greater in NBCS, and NBCS also reached a positive energy balance earlier than HBCS. The greater reduction in body mass in HBCS was accompanied by greater concentrations of non-esterified fatty acids, and ß-hydroxybutyrate in serum after calving than in NBCS, indicating increased lipomobilization and ketogenesis. The mean concentrations of insulin across all time-points were greater in HBCS than in NBCS. In both groups, insulin and IGF-1 concentrations were lower p.p than in a.p. Greater free thyroxine (fT4) concentrations and a lower free 3-3'-5-triiodothyronine (fT3)/fT4 ratio were observed in HBCS than in NBCS a.p., whereas p.p. fT3/fT4 ratio followed a reverse pattern. The variables indicative for oxidative status had characteristic time courses; group differences were limited to greater plasma ferric reducing ability values in NBSC. The results demonstrate that the combination of pre-selection according to BCS and differential feeding before dry-off to promote the difference was successful in obtaining cows that differ in the intensity of mobilizing body reserves. The HBCS cows were metabolically challenged due to intense mobilization of body fat, associated with reduced early lactation dry matter intake and compromised antioxidative capacity.

Detection of integrins in human cataract lens epithelial cells and two mammalian lens epithelial cell lines.

AIM: To compare the incidence of various integrin subunits in human cataract anterior lens epithelial cells (A-LEC) and in two mammalian LEC lines. METHODS: Circular sections of anterior capsules with attached LEC were obtained during cataract surgery. Integrin subunits were immunolocalised in these anterior LEC and in a human and rabbit LEC line, using four monoclonal antibodies specific for subunits alpha2, alpha3, and alpha5, and beta subunit 2. RESULTS: All of these subunits were found in at least a proportion A-LEC samples as follows: alpha2 71%, alpha3 92%, alpha5 62%, and beta2 24%. The human LEC line was immunoreactive for alpha2 and alpha3 only. The rabbit lens epithelial cell line was immunoreactive for alpha5 but there was no staining for alpha2, alpha3, or beta2. CONCLUSION: The A-LEC and mammalian LEC lines showed a similarity in their pattern of integrin expression. As these integrins are receptors for extracellular matrix (ECM) components, they are likely to be associated with the attachment and migration of LECs that precedes capsular opacification. Therefore these cell lines may be useful in the elucidation of mechanisms involved the pathogenesis of capsule opacification.

Patient satisfaction in our initial experience with endonasal endoscopic non-laser dacryocystorhinostomy.

BACKGROUND/AIMS: Endonasal endoscopic dacryocystorhinostomy (EN-DCR) is now a well-established procedure to relieve nasolacrimal duct obstruction. In the past, attempts have been made to comment on the anatomical success of the procedure. However, no studies have been conducted to evaluate patient satisfaction with the EN non-laser DCR procedure in comparison with the surgeon's experience. METHODS: Records of patients undergoing EN-DCR and external DCR (ET-DCR) surgery were reviewed. A telephone questionnaire was used to assess patient satisfaction with both procedures. Data were analyzed with Fisher's exact test and the chi-square test. RESULTS: Twenty primary EN-DCR's and 16 revision EN-DCR's were performed by the same surgeon (RM) over a three-year period. At last review, 89% of ET-DCR and 75% of EN-DCR procedures were noted to have a patent sac washout performed in the eye clinic. A telephonic interview revealed no significant difference between the surgical outcome [15/20 (75%)] and patient satisfaction [14/20 (70%)] with the primary EN-DCR procedure. Patient satisfaction with revision EN-DCR [10/16 (63%)] was slightly poorer than the surgical outcome recorded for revision EN-DCR [12/16 (75%)] but this was also not statistically significant. Telephonic interview was possible for 42/64 (66%) patients undergoing primary external ET-DCR's and a total of 36/42 (86%) patients were satisfied with the procedure. Patient age, laterality, duration of symptoms, previous ocular procedures or preexisting ocular disease and associated ENT procedures did not alter the surgical result or patient satisfaction in either group. CONCLUSIONS: This study suggests that patient satisfaction with endoscopic endonasal non-laser DCR for primary or revision DCR surgery is comparable to that with the external-DCR technique since there was no significant difference in patient satisfaction between the two groups of patients. Patient perception of their symptomatic improvement was lower (though not statistically significant) in relation to the final clinical assessment of the outcome of both primary and revision EN-DCR.

Histological and morphometric analysis of the effects of argon laser epilation.

AIM: To analyse the location and extent of tissue damage induced after argon laser epilation. METHODS: Laser burns were applied to the lid margins of four patients before excision for entropion ("live tissue") and the lid margin of one patient was lasered after an excision for ectropion ("dead tissue"). The laser burns were directed towards the lash follicle and between 10 and 50 burns were applied with an argon blue-green laser set at power 0.9-1.0 W, at 0.1-0.2 second duration and a 100 micro m spot size. The tissues were processed for conventional histology. Serial sections were obtained and used for area measurements and three dimensional reconstructions of the burns to determine the volume and location of tissue destruction. RESULTS: The laser created a cone-shaped region of tissue ablation with surrounding coagulative necroses. Maximum burn depth was 1.2 mm in dead tissue and 0.8 mm in live tissue. Maximum necrosis depth was 1.4 mm in dead tissue and 0.9 mm in live tissue. Follicle depth ranged from 0.8 mm to 1.9 mm. Some of the burns had been misdirected in the dermis leaving target hair follicles intact, despite being of adequate depth. CONCLUSIONS: The argon laser has some potential for ablation of lash follicles, but accurate placement of the burn is essential and energy levels greater than those currently recommended should be applied. The treatment is ineffective in patients unable to remain immobile.

Expression of CD18, CD49b, CD49c and CD49e on lens anterior capsules in human cataracts.

PURPOSE: To examine the lens epithelial cells obtained from the anterior lens capsules removed during cataract surgery and detect various subclasses of the cell surface adhesion molecules known as integrins. METHODS: The circular sections of anterior capsules with attached lens epithelial cells (LECs) were obtained during cataract surgery from 28 patients. The lens capsules were immunohistochemically stained. RESULTS: CD49b CD49c, CD49e, and CD18 were detected in varying degrees in specimens obtained from human cataractous lenses. The positive percentages were 33, 75, 33, and 20%, respectively. The most striking feature was the increasing staining profiles towards the edges of the capsules (away from the central part of the lens capsules) for CD49c, suggesting that the LECs showed higher immunoreactivity for this antibody. The immunoreactivity for CD49b and CD49e was weaker. This was absent for CD18 in the central part of the lens capsules. CONCLUSION: The positive expression of antibodies suggests that specific integrin subunits were expressed in LECs of human cataracts. These results suggest that lens epithelial cells expressing CD49b, CD49c, CD49e, and CD18 might be precursors in the process of anterior lens epithelial cell (A cell) adhesion, and hence play a role in anterior capsule opacification or in subsequent migration and a possible role in posterior capsule opacification.

Pre-operative estimation of primary breast cancer size: a comparison of clinical assessment, mammography and ultrasound.

This prospective study aimed to determine which is the most precise modality for the pre-operative measurement of primary breast cancers: clinical palpation; mammography; or ultrasound. Analysis of the difference between the measurement of the maximum tumour diameter by these three modalities and by the histological measurement was performed in 210 cases. Clinical palpation tended to overestimate tumour size and gave the largest standard deviation of the difference. Ultrasound and mammography both gave a similar standard deviation of the difference, with ultrasound tending to underestimate tumour size. For all modalities, the standard deviation and the 95% confidence intervals of the difference increased with increasing tumour size. There is little difference between the precision of ultrasound and mammography in measuring tumour size. The wide 95% confidence intervals for any method of pre-operative tumour measurement should be considered when planning patient management.

Study on risk factors and their association with subclinical mastitis in lactating dairy cows in Trinidad.

A cross-sectional study was conducted on dairy farms in eight milking centres in Trinidad to determine the prevalence of risk factors for mastitis and to assess their relationship to occurrence of subclinical mastitis. The California mastitis test (CMT) was used to determine the prevalence of subclinical mastitis by estimating the somatic cell counts in bulk and composite milk. Of a total of 177 dairy farms studied, 121 (68.4%), 39 (22.0%) and 17 (9.6%) practised semi-intensive, extensive and intensive management systems, respectively. A total of 129 (72.9%), 37 (20.9%) and 11 (6.2%) farms milked cows in parlours, stanchions and pasture/out-on-field, respectively. Based on sanitary practices, 40 (22.6%), 123 (69.5%), and 14 (7.9%) farms were classified as good, fair, and poor, respectively, while 76 (42.9%) and 60 (33.9%) farms reported to rarely experience and frequently experience water shortages, respectively. Amongst the 177 farms, only seven (4.0%) used machine-milking primarily, 152 (85.9%) screened for mastitis as a routine, 18 (10.2%) teat dipped, and 49 (27.7%) practised dry cow therapy. To detect mastitis, of 152 farms involved, 20 (13.2%) used the strip cup while only two (1.3%) employed the CMT. Pipe-borne water delivered directly from the hose was the only source of water to 91 (51.4%) farms while seven (4.0%) and eight (4.5%) farms used only well and surface water (ponds and rivers), respectively. Based on bulk milk samples, the farm prevalence of subclinical mastitis was 60.5% (107 of 177) with a range from 33.3% (centre 5H) to 100.0% (centre 2B). The difference was statistically significant (P < 0.01; chi 2). However, using composite milk, the farm prevalence of subclinical mastitis was 52.5% (93 of 177) with a range from 21.2% (centre 5H) to 92.9% (centre 2B) and again, the difference in prevalence was statistically significant (P < 0.001; chi 2). Subclinical mastitis was detected in 150 (45.0%) of 333 lactating cows screened and the range of prevalence was from 17.9% (centre 5H) to 56.3% (centre 1C). The difference was statistically significant (P < 0.001; chi 2). Of a total of 14 risk factors for mastitis studied which were related to animal husbandry, personnel, mastitis control and water, only two, the herd size and practice of dry cow therapy were significantly (P < 0.05; chi 2) associated with subclinical mastitis. It was concluded that the high prevalence of subclinical mastitis in Trinidad dairy herds could significantly reduce milk production with associated economic loss. Although a majority of the risk factors studied were not found to be significantly associated with the occurrence of subclinical mastitis possibly due to confounding factors, the need to eliminate or reduce these risk factors cannot be over-emphasized.

Prevalence and characteristics of Staphylococcus aureus strains isolated from bulk and composite milk and cattle handlers.

The prevalence and characteristics of Staphylococcus aureus strains isolated from bulk and composite milk and from cattle handlers on dairy farms in Trinidad were determined. S. aureus strains were isolated from all 175 bulk milk samples tested (100%) while 280 of 287 composite milk samples (97.6%) yielded S. aureus. The mean counts of S. aureus in bulk milk ranged from 5.9 x 10(3) to 1.2 x 10(5) CFU/ml compared with mean S. aureus counts in composite milk which ranged from 2.4 x 10(3) to 3.0 x 10(4) CFU/ml. Of the 105 strains of S. aureus from bulk milk tested, 45 (42.9%) were enterotoxigenic elaborating staphylococcal enterotoxin A (SEA), SEB, SEC, SED, or a combination compared to 69 of 146 strains (47.3%) recovered from composite milk which were enterotoxigenic, but the difference was not statistically significant (P > = 0.05; chi 2). Twenty-two of 42 bulk milk samples containing enterotoxigenic S. aureus (52.4%) had counts of the organism which exceeded 10(4) CFU/ml. For S. aureus strains isolated from cattle handlers, 66 of 146 (45.2%) were enterotoxigenic. Prevalence of resistance to nine antimicrobial agents tested was 18.7% and 12.9% among bulk milk and composite milk isolates, respectively, compared to 49.3% and 69.5%. among isolates from human anterior nares and hand swabs, respectively. Resistance to ampicillin and penicillin was highest among both milk (12.2%) and human (53.6%) isolates of S. aureus, and the difference was statistically significant (P < or = 0.001; chi 2). It was concluded that bulk milk containing relatively high counts of enterotoxigenic S. aureus may constitute a health hazard to consumers.

Cytokeratin expression in breast cancer: phenotypic changes associated with disease progression.

Transition from a normal to a cancerous state is marked by alterations in the cytoskeletal structure of those cells involved. We have examined such changes to determine if these transitions are markers of disease progression. Cytokeratin (CK) protein and messenger RNA (mRNA) expression were examined in malignant and benign breast tissues. Flow cytometric results demonstrated a significant correlation between cytokeratin protein expression detected by 5D3 antibody, specific for cytokeratins 8, 18, and 19 and axillary node metastasis (P = 0.01). A threshold of positivity of 338,000 molecules/cell was determined and reflected the wide range in cytokeratin levels expressed by normal or benign tissues. Examination of cytokeratins 8, 18, and 19 revealed a consistent pattern of expression with respect to tumor grade. Only cytokeratin 19 showed significant correlation with increasing tumor size (P = 0.006). mRNA expression for cytokeratin 8 was significantly higher in node-positive compared with node-negative disease (P = 0.02). Cytokeratin 18 mRNA levels were significantly lower in both node-negative (P = 0.03) and node-positive (P = 0.02) patients when compared with benign samples. Increased levels of cytokeratin 18 mRNA showed an inverse relationship with protein expression (P = 0.05). The results indicate that cytokeratin expression in breast cancer may be associated with tumor progression. Furthermore, the alteration in the expression of individual cytokeratins deserves further investigation to determine the consequences of these changes with respect to cellular function.

The effect of 3-week tamoxifen treatment on oestrogen receptor levels in primary breast tumours: a flow cytometric study.

The effect of 3-week, preoperative tamoxifen treatment on oestrogen receptor (ER) levels, expressed by primary breast tumours, was examined. Patients (age-matched) with breast cancer, confirmed by fine-needle aspiration, were either treated with 20 mg ml(-1) oral tamoxifen per day or received no medication in the 3-week interval between assessment and surgery. Quantification of ER using flow cytometry was performed on the surgically removed tumour samples from tamoxifen-treated (n = 40) and control (n = 38, untreated) patient groups. The tumours were mechanically disaggregated, and saponin treatment rendered these cells permeable to antibodies. Using dual-parameter labelling with a FITC-conjugated antibody (NCL-5D3) directed against cytokeratin 8/18/19 and a biotinylated antibody (DAKO-ER 1D5) directed against the oestrogen receptor, ER quantification was determined on a number of receptors per cell basis. Using QC quantum bead standards, ER levels in the epithelial cell population, the non-epithelial cell population and the whole-cell population (ER+) were calculated. ER levels were significantly lower in the total cell population than tamoxifen-treated patients (P = 0.002) when compared with the control (untreated) group. By using a gating procedure using 5D3 antibody positivity, a significantly lower level was detected on examining the cytokeratin-positive population alone (P = 0.006). Using a complementary gating technique, ER levels were quantified in the cytokeratin-negative cell population. Examination of this group of cells showed no significant difference between the levels of oestrogen receptor found in the tamoxifen-treated and untreated groups (P = 0.4). We have demonstrated that ER levels can be monitored by flow cytometry. ER levels in patients treated with tamoxifen 3 weeks before operation are significantly lower than in a comparative group of patients who received no drug. Furthermore, the most significant difference in receptor levels is seen by quantification of total ER levels expressed by all the tissue.

Prevalence and characteristics of Staphylococcus aureus strains isolated from bulk and composite milk and cattle handlers

The prevalence and characteristics of Staphylococcus aureus strains isolated from bulk and composite milk and from cattle handlers on dairy farms in Trinidad were determined. S. aureus strains isolated from all 175 bulk milk samples tested (100 percent) while 280 of 287 composite milk samples (97.6 percent) yielded S. aureus. The mean counts of S. aureus in bulk milk ranged from 5.9 x 10(3) to 1.2 x 10(5) CFU/ml compard with mean S. aureus counts in composited milk which ranged from 2.4 x 10(3) to 3.0 x 10(4) CFU/ml. Of the 105 strains of S. aureus from bulk milk tested, 45 (42.9 percent) were enterotoxigenic elaborating staphylococcal enterotoxin A (SEA), SEB, SEC, SED, or a combination compared to 69 of 146 strains (47.3 percent) recovered from composite milk which were enterotoxigenic but the difference was not statistically significant (P > = 0.05; chi 2). Twenty-two of 42 bulk milk samples containing enterotoxigenic S. auerus (52.4 percent) had counts of the organism which exceeded 10(4) CFU/ml. For S. aureus strains isolated from cattle handlers, 66 of 146 (45.2 percent) were enterotoxigenic. Prevalence of resistance to nine antimicrobial agents tested was 18.7 percent and 12.9 percent among bulk milk and composite milk isolates, respectively, compared to 49.3 percent and 69.5 percent among isolates from human anterior nares and hand swabs, respectively. Resistance to ampicillin and penicillin was highest among both milk (12.2 percent) and human (53.6 percent) isolates of S. aureus, and the difference was statistically significant (P < or = 0.001); chi 2). It was concluded that bulk milk containing relatively high counts of enterotoxigenic S. aureus may constitute a health hazard to consumers(AU)

Prevalence and characteristics of Staphylococcus aureus strains isolated from bulk and composite milk cattle handlers

The prevalence and characteristics of Staphylococcus aureus strains isolated from bulk and composite milk and from cattle handlers on dairy farm all 175 bulk milk samples tested (100 percent) while 280 of 287 composite milk samples (97.6 percent) yielded S. aureus. The mean counts of S. aureus in bulk milk ranged from 5.9 x 10(3) to 1.2 x 10(5) CFU/ml compared with mean S. aureus counts in composite mild which ranged from 2.4 x 10(3) to 3.0 x 10(4) CFU/ml. Of the 105 strains of S. aureus from bulk milk tested, 45 (42.9 percent) were enterotoxigenic elaborating staphylococcal enterotoxin A (SEA), SEB, SEC, SED, or a combination compared to 69 of 146 stains (47.3 percent) recovered from composite milk which were enterotoxigenic, but the difference was not statistically significant (P > 0.05; chi 2). Twenty-two of 42 bulk milk samples containing enterotoxigenic S. aureus (52.4 percent) had counts of the organism which exceeded 10(4) CFU/ml. For S. aureus strains isolated from cattle handlers, 66 of 146 (45.2 percent) were enterotoxigenic. Prevalence of resistance to nine antimicrobial agents tested was 18.7 percent and 12.9 percent among bulk milk and composite milk isolates, respectively, compared to 49.3 percent and 69.5 percent among isolates from human anterior nares and hand swabs, respectively. Resistance to ampicillin and penicillin was highest among both milk (12.2 percent) and human (53.6 percent) isolates of S. aureus, and the difference was stastically significant (P < or in 0.001; chi 2). It was concluded that bulk milk containing relatively high counts of enterotoxigenic S. aureus may constitute a health hazard to consumers(AU)

Support line and tube visibility in chest examinations using computed radiography.

The visibility of support lines and tubes was compared in computed radiography (CR) and screen-film adult chest radiographs. Parameters investigated were radiation dose, image minification, and the use of unsharp mask enhancement. Five radiologists rated the visibility of support lines and tubes on a five-point scale ranging from 1 (entire course of line visible) to 5 (line not visible or only small portion seen). These CR results were compared with the visibility of support lines and tubes as assessed by the same readers for conventional screen-film radiographs (600 speed). Support line and tube visibility improved with image enhancement, image minification, and increasing radiation dose. At the same radiation exposure, support line and tube visibility of the screen-film combination was superior to that of standard CR images. Application of an unsharp mask enhancement algorithm to CR images, however, significantly improved support line and tube visibility in comparison to that obtained with the screen-film combination. It was concluded that unsharp mask processing is a valuable tool for improving the visibility of support lines and tubes in CR chest radiographs.

Prevalence and Characteristics of Strains of Escherichia coli Isolated from Milk and Feces of Cows on Dairy Farms in Trinidad.

The prevalence, counts, and characteristics of Escherichia coli isolated from bulk milk, composite milk, and feces of dairy cows in eight milking centers were determined. The microbial quality of water used during milking was also investigated. Of a total of 175 bulk milk samples studied, 83 (47.4%) contained E. coli compared to only 14 (4.9%) of 287 composite milk samples and the difference was statistically significant (P ≤ 0.001; χ2). The ranges in mean counts of E. coli per milliliter of bulk milk and composite milk were 8.4 × 103 to 2.0 × 105 and 2.1 × 101 to 2.0 × 102, respectively. The prevalences and mean counts of E. coli and mean pH values for bulk milk from farms with and without subclinically mastitic cows were not significantly different (P ≥ 0.05; χ2). A total of 204 (65.2%) of 313 fecal samples of dairy cows were positive for E. coli . Of the samples of water used during milking collected from 171 dairy farms, 80 (46.8%) were free of coliforms while 59 (34.5%), 12 (7.0%), and 8 (4.7%) had ranges of coliform counts per 100 ml of 1 to 50, 51 to 100, and over 250, respectively. Twenty-six (27.7%) and 17 (18.5%) of 94 strains of E. coli isolated from bulk milk were enteropathogenic E. coli (EPEC) and verocytotoxigenic E. coli (VTEC) strains, respectively. Compared with 204 fecal strains of E. coli , 16 (7.8%) and 68 (35.6%) were EPEC and VTEC strains, respectively, and the differences were statistically significant (P ≤ 0.01; χ2). Similarly, the difference in prevalence of resistance to one or more of nine antimicrobial agents between bulk milk isolates (69.6%) and fecal isolates (25.9%) was statistically significant (P ≤ 0.001; χ2), and resistance to ampicillin was the most prevalent type of resistance for strains of E. coli from bulk milk isolates. It was concluded that the relatively high counts of toxigenic E. coli in bulk milk originating from dairy farms in Trinidad could pose a health risk to consumers. The poor microbial quality of water used on farms may be an important source of contamination of milk.

Relatedness of Staphylococcus aureus strains isolated from milk and human handlers in dairy farms in Trinidad.

The susceptibility of S. aureus strains isolated from milk and human handlers in dairy farms in Trinidad to bacteriophages was determined. Of the 110 strains isolated from bulk milk, 73 (66.4%) were typable either at routine test dilution (RTD) or 100-RDT compared to 108 (72.5%) of 149 strains from composite milk sensitive but the difference was not statistically significant (P > or = 0.05; chi 2). Strains of S. aureus from human handlers had significantly (P < or = 0.05; chi 2) lower sensitivity, with only 90 (59.6%) of 151 strains typable. Phages in various groups were predominantly more active on both milk isolates, 54.1% (98 of 181) and human strains, 73.3% (66 of 90). Phage 42D alone lysed 22 (12.2%) but with other phages typed 90 (49.7%) of 181 typable strains from milk compared to a lytic activity of only 1.1% (1 of 90) alone and 35 (38.9%) with other phages for strains isolated from human handlers. The differences were however not statistically significant (P > or = 0.05; chi 2). Relatedness of S. aureus strains isolated from bulk milk, composite milk and human handlers on each farm was demonstrated in 21 (46.7%) of 45 dairy farms using the phage patterns detected. Similarly, the relatedness of S. aureus strains isolated from the anterior nares and hands of each human milker was detected on 10 (35.7%) of 28 dairy farms studied. It was concluded that S. aureus strains from human milkers contaminated both composite and bulk milk on the farms studied while bovine strains of S. aureus were also acquired by humans during milking.

Prevalence of Salmonella, Listeria monocytogenes, Campylobacter spp., Yersinia enterocolitica and Cryptosporidium spp. in bulk milk, cows' faeces and effluents of dairy farms in Trinidad.

The prevalence of Listeria, Salmonella, Campylobacter, Yersinia and Cryptosporidium species in bulk milk, faeces of dairy cows and effluents of milking parlours from dairy farms in Trinidad was investigated. Of the 177 bulk milk samples studied, 3 (1.7%), 3 (1.7%) and 2 (1.1%) were positive for L. monocytogenes, Salmonella spp. and Y. enterocolitica, respectively, but were all negative for Campylobacter and Cryptosporidium species. From 333 faecal samples tested, L. monocytogenes, Campylobacter spp. and Cryptosporidium spp. were detected in 11 (3.3%), 19 (5.7%) and 7 (2.1%), respectively, which were significantly (P < 0.05; chi 2) higher than the detection rate (0%) for Yersinia spp. Salmonella spp. were isolated from 3 (0.9%) of the faecal samples. From 168 effluent samples cultured, Campylobacter spp. were isolated from 7 (4.2%) samples while Salmonella was recovered from only 1(0.6%) sample with no sample positive for either Yersinia or Listeria. The difference was significant (P < 0.05; chi 2). A total of 19 (73.1%) of 26 Campylobacter isolates exhibited resistance to one or more of the six antimicrobial agents tested. All 14 (100%) isolates of L. monocytogenes were resistant to at least one agent while all Salmonella and Yersinia enterocolitica strains were susceptible to all antimicrobial agents used. It was concluded that the five enteropathogens tested were present on dairy farms in Trinidad and the potential for milk-borne diseases, due to these pathogens, exists for consumers, emphasizing the need for good sanitary practices.