The Use of Artificial Intelligence for the Prediction of Periprosthetic Joint Infection Following Aseptic Revision Total Knee Arthroplasty

Periprosthetic joint infection (PJI) following revision total knee arthroplasty (TKA) for aseptic failure is associated with poor outcomes, patient morbidity, and high health care expenditures. The aim of this study was to develop novel machine learning algorithms for the prediction of PJI following revision TKA for patients with aseptic indications for revision surgery. A single-institution database consisting of 1,432 consecutive revision TKA patients with aseptic etiologies was retrospectively identified. The patient cohort included 208 patients (14.5%) who underwent re-revision surgery for PJI. Three machine learning algorithms (artificial neural networks, support vector machines, k-nearest neighbors) were developed to predict this outcome and these models were assessed by discrimination, calibration, and decision curve analysis. This is a retrospective study. Among the three machine learning models, the neural network model achieved the best performance across discrimination (area under the receiver operating characteristic curve = 0.78), calibration, and decision curve analysis. The strongest predictors for PJI following revision TKA for aseptic reasons were prior open procedure prior to revision surgery, drug abuse, obesity, and diabetes. This study utilized machine learning as a tool for the prediction of PJI following revision TKA for aseptic failure with excellent performance. The validated machine learning models can aid surgeons in patient-specific risk stratifying to assist in preoperative counseling and clinical decision making for patients undergoing aseptic revision TKA.

Machine learning models accurately predict recurrent infection following revision total knee arthroplasty for periprosthetic joint infection

PURPOSE

This study aimed to develop and validate machine-learning models for the prediction of recurrent infection in patients following revision total knee arthroplasty for periprosthetic joint infection.

METHODS

A total of 618 consecutive patients underwent revision total knee arthroplasty for periprosthetic joint infection. The patient cohort included 165 patients with confirmed recurrent periprosthetic joint infection (PJI). Potential risk factors including patient demographics and surgical characteristics served as input to three machine-learning models which were developed to predict recurrent periprosthetic joint. The machine-learning models were assessed by discrimination, calibration and decision curve analysis.

RESULTS

The factors most significantly associated with recurrent PJI in patients following revision total knee arthroplasty for PJI included irrigation and debridement with/without modular component exchange (p < 0.001), > 4 prior open surgeries (p < 0.001), metastatic disease (p < 0.001), drug abuse (p < 0.001), HIV/AIDS (p < 0.01), presence of Enterococcus species (p < 0.01) and obesity (p < 0.01). The machine-learning models all achieved excellent performance across discrimination (AUC range 0.81-0.84).

CONCLUSION

This study developed three machine-learning models for the prediction of recurrent infections in patients following revision total knee arthroplasty for periprosthetic joint infection. The strongest predictors were previous irrigation and debridement with or without modular component exchange and prior open surgeries. The study findings show excellent model performance, highlighting the potential of these computational tools in quantifying increased risks of recurrent PJI to optimize patient outcomes.

LEVEL OF EVIDENCE

IV.

Kawasaki disease for the paediatric dermatologist: skin manifestations and new insights into the pathophysiology

Early diagnosis of Kawasaki disease (KD) is critical to allow prompt initiation of treatment and avoid cardiac complications. All children with KD have fever accompanied by clinical signs, with four of the five classic criteria for complete KD being mucocutaneous, thus creating an important role for dermatologists. Moreover, dermatologists must be familiar with other dermatological findings that are not included in the American Heart Association classification criteria but can support the diagnosis, particularly in incomplete forms of the disease. We review the skin manifestations described for KD and perform an overview of pathophysiological advances and new treatments.

Characterization of circulating immune cells in acute Kawasaki disease suggests exposure to different antigens

Kawasaki disease (KD) is an acute pediatric vasculitis of unknown etiology that can cause coronary artery aneurysms, and is the leading cause of acquired heart disease in children. We studied aspects of the innate and adaptive immune response in 17 acute KD children prior to treatment with intravenous immunoglobulin. Distinct patterns within the innate immune response correlated with specific clinical features. Proinflammatory myeloid dendritic cells (mDC) were abundant in four of 17 (23·5%) subjects who were older and manifested severe inflammation with clinical myocarditis and elevated hepatobiliary enzyme levels. Of the nine subjects with low levels of anti‐inflammatory, tolerogenic mDC, six had enlarged cervical lymph nodes at diagnosis. In contrast, the adaptive immune repertoire varied greatly with no discernible patterns or associations with clinical features. Two subjects with aneurysms had numerous circulating CD8⁺ T cells. Ten subjects showed low CD4⁺ T cell numbers and seven subjects had CD4⁺ T cells in the normal range. CD4⁺ T cells expressed interleukin‐7 receptor (IL‐7R), suggesting repeated antigenic stimulation. Thymic‐derived regulatory T cells (nT_reg) and peripherally induced regulatory T cells (iT_reg) were also enumerated, with the majority having the nT_reg phenotype. Natural killer (NK) and NK T cell numbers were similar across all subjects. Taken together, the results of the immune monitoring suggest that KD may have multiple triggers that stimulate different arms of the innate and adaptive compartment in KD patients. Thus, it is possible that diverse antigens may participate in the pathogenesis of KD.

Pregnancy in women with a history of Kawasaki disease: management and outcomes

OBJECTIVE

To characterise the obstetrical management and outcomes in a series of women with a history of Kawasaki disease (KD) in childhood.

DESIGN

Retrospective case series.

SETTING

Tertiary healthcare setting in the USA.

POPULATION

Women with a history of KD in childhood.

METHODS

Women completed a detailed health questionnaire and participated in research imaging studies as part of the San Diego Adult KD Collaborative Study.

MAIN OUTCOME MEASURES

Obstetrical management, complications during pregnancy and delivery, and infant outcomes.

RESULTS

Ten women with a history of KD in childhood carried a total of 21 pregnancies to term. There were no cardiovascular complications during labour and delivery despite important cardiovascular abnormalities in four of the ten subjects. Pregnancy was complicated by pre-eclampsia and the post-partum course was complicated by haemorrhage in one subject each. Two of the 21 progeny subsequently developed KD.

CONCLUSIONS

Women with important cardiovascular sequelae from KD in childhood should be managed by a team that includes both a maternal-fetal medicine specialist and a cardiologist. Pre-pregnancy counselling should include delineation of the woman's current functional and structural cardiovascular status and appropriate adjustment of medications, but excellent outcomes are possible with appropriate care. Review of the English and Japanese literature on KD and pregnancy revealed the occurrence of myocardial infarction during pregnancy in women with missed KD and aneurysms that were not diagnosed until their acute event. Our study highlights the need for counselling with regard to the increased genetic risk of KD in offspring born to these mothers.

Immune-monitoring in Kawasaki disease patients treated with infliximab and intravenous immunoglobulin

The expansion of regulatory T cells (Treg ) controls inflammation in children with acute Kawasaki disease (KD). Blockade of tumour necrosis factor (TNF)-α is an emerging therapy for KD patients with refractory inflammation, but there is concern that this therapy could impede the host immune regulation. To define the effect of TNF-α blockade, we conducted ex-vivo immune-monitoring in KD subjects who participated in a randomized, double-blind, placebo-controlled clinical trial of the addition of infliximab to standard intravenous immunoglobulin (IVIG) therapy. We enumerated circulating myeloid and plasmocytoid dendritic cells (DC), regulatory T cells (Treg ) and memory T cells (Tmem ) in 14 consecutive, unselected KD patients (seven treated with IVIG, seven with IVIG + infliximab) at three time-points: (i) acute phase prior to treatment, (ii) subacute phase and (iii) convalescent phase. Myeloid DC (mDC), but not plasmacytoid DC (pDC), were numerous in the peripheral blood in acute KD subjects and decreased in the subacute phase in both IVIG(-) and IVIG (+)  infliximab-treated groups. The co-stimulatory molecule for antigen presentation to T cells and CD86 decreased in mDC from acute to subacute time-points in both treatment groups, but not in the single patient who developed coronary artery aneurysms. We also defined tolerogenic mDC that expand in the subacute phase of KD not impaired by infliximab treatment. Treg and Tmem expanded after treatment with no significant differences between the two groups. Treatment of KD patients with infliximab does not adversely affect generation of tolerogenic mDC or the development of T cell regulation and memory.

Technical note: Use of near-infrared reflectance spectroscopy to predict intake and digestibility in bulls and steers

Multiple fecal samples were collected from growing Angus bulls (264 to 419 kg of BW, 3.0 to 11.4 kg/d of DMI) to predict DMI of a corn-silage-based diet. Contemporaneous digestion trials were conducted with the same diet in 12 steers in yr 1 to 3 and bulls in yr 4. Near-infrared spectra from fecal samples (n = 730 from 282 growing bulls, n = 240 from 36 steers and 12 bulls for digestion trials) were obtained from dried and ground fecal samples, and modified partial least squares regression was used to develop equations to predict DMI and DM digestibility (DMD). Although mean predicted DMI of the growing bulls (7.52 ± 0.04 kg/d or 22.4 ± 0.1 g/kg of BW) was within 2% of mean measured DMI (7.63 ± 0.06 kg/d or 22.7 ± 0.1 g/kg of BW), the mean of paired differences within samples (0.11 ± 0.04 kg/d or 0.3 ± 0.1 g/kg of BW) was greater (P < 0.01) than zero. Measured DMD (72.3 ± 0.5%) was identical (P < 0.97) to predicted DMD (72.3 ± 0.5%), and DMD for bulls in the digestion trial did not differ (P < 0.27) from DMD for steers. Prediction of intake requires incorporation of some measured values from the set of fecal samples to be predicted. Lack of similarity between spectra of fecal grab samples from the growing bulls and daily fecal collection of steers and bulls in the digestion trials in this study indicates the need for further verification before prediction of DMD with fecal grab samples.

Intake and digestibility of 'coastal' bermudagrass hay from treated swine waste using subsurface drip irrigation

Waste handling systems for confined swine production in the upper South (approximately 32-37 degrees N and 79-93 degrees W) depend mainly on anaerobic lagoons and application of the waste effluent to cropland. The main objective of this study was to evaluate the quality of 'Coastal' bermudagrass [Cynodon dactylon (L.) Pers.] hay receiving effluent generated from a raw swine waste treatment system designed to reduce P and K concentrations and delivered by subsurface drip irrigation (SDI) compared with hay produced from commercial N fertilizer. Eight treatments, consisting of commercial N fertilizer or effluent, each irrigated at two irrigation rates (75 and 100% of estimated evapotranspiration) and two lateral spacings (0.6 and 1.2 m), were compared with a control treatment of commercial N fertilizer without irrigation. Three harvests were taken in each of 2 yr and five of the six evaluated using wether sheep (30-45 kg). Greatest dry matter intake (DMI) per unit body weight occurred for the control vs. all irrigated treatments (1.94 vs. 1.77 kg 100(-1) kg; P = 0.02; SEM = 0.11). Among irrigated treatments, DMI was greatest from commercial N vs. effluent (1.81 vs. 1.71 kg 100(-1) kg; P = 0.05; SEM = 0.11). Dry matter intake was similar for the 75% rate treatments and the non-irrigated treatment (mean, 1.87 kg 100(-1) kg) but was reduced for the 100% rate (1.94 vs. 1.72 kg 100(-1) kg; P = 0.03; SEM = 0.11). Hay from the 75% rate was more digestible than hay from the 100% rate (527 vs. 508 g kg(-1); P = 0.03; SEM = 21). The SDI system functioned well, and lateral spacing did not alter hay quality. Treated waste from a raw waste treatment system was readily delivered by SDI at the recommended rate to produce bermudagrass hay of adequate quality for ruminant production systems.

Effect of feeding corn, hull-less or hulled barley on fermentation by mixed cultures of ruminal microorganisms

Increased demands for corn grain warrant the evaluation of alternative grain types for ruminant production systems. This study was conducted to determine the effects of hulled and hull-less barley (Hordeum vulgare L.) cultivars compared with corn (Zea mays L.) as an alternative grain type on fermentation in cultures of mixed ruminal microorganisms. Three continuous fermentors were fed 14 g of dry feed per day (divided equally between 2 feedings) consisting of alfalfa (Medicago sativa L.) hay pellets (40% of dry matter) and 1) ground corn, 2) hulled barley, or 3) hull-less barley concentrate (60% of dry matter) in each fermentor. Following an adaptation period of 5 d, culture samples were taken at 2 h after the morning feeding on d 6, 7, and 8 of each period for analysis. A second run of the fermentors followed the same treatment sequence to provide replication. Culture pH was reduced with corn (5.55) and did not differ between barley cultivars (average pH 5.89). Total volatile fatty acid concentration and acetate to propionate ratio were not different across grain type or barley cultivar with the exception of greater total volatile fatty acid concentrations with hull-less barley. Corn produced less methane (14.6 mmol/d) and ammonia-N (7.3 mg/100 mL) compared with barley (33.1 mmol/d and 22 mg/100 mL, respectively); methane was greater with hull-less barley but ammonia-N concentration was similar between the 2 barley cultivars. Hull-less barley had greater digestibility compared with hulled barley, and corn had reduced digestibility compared with barley. Concentrations of C18:0 were greater and those of C18:1 and C18:2 lesser in cultures fed hulled and hull-less barley compared with corn. Our data indicate that grain type and barley cultivar have an impact on ruminal fermentation. The lesser starch concentration of barley minimized the drop in culture pH and improved digestibility.

The interaction of harvesting time of day of switchgrass hay and ruminal degradability of supplemental protein offered to beef steers1,2

The objective of this study was to evaluate an interaction between harvest at 0600 (AM) vs. 1800 (PM) with high (HI) or low (LO) ruminal degradability of a protein supplement to change voluntary intake, digestion, or N retention by steers offered switchgrass (Panicum virgatum L.) hay. Black steers (255 +/- 14 kg of BW) were blocked by BW, and then randomly assigned (5 steers each) to AM/HI, PM/HI, AM/LO, or PM/LO treatment groups. Steers were group-housed in covered, outdoor pens with individual feeding gates. After adaptation and standardization, intake was measured for 21 d followed by a digestion trial (5 d of total collection). Steers were offered 767 (LO) or 825 (HI) g/d of supplement to provide 268 g of CP/d. Compared with AM, PM had greater (P = 0.01) concentrations of total nonstructural carbohydrate (TNC, 71 vs. 56 g/kg of DM), and lesser concentrations of NDF (760 vs. 770 g/kg of DM, P = 0.02), ADF (417 vs. 427 g/kg of DM, P = 0.02), and CP (55.9 vs. 58.6 g/ kg of DM, P = 0.07). Protein fractions A, B(2), and B(3) were similar for AM and PM, but HI contained more (P < 0.02) A (694 vs. 296 g/kg of protein) and less B(2) (174 vs. 554 g/kg of protein) fraction than LO. Harvest interacted with supplement to increase (P = 0.07) ad libitum digestible DMI for steers offered PM/HI (11.4 g/kg of BW daily) compared with steers offered PM/LO (10.2 g/kg of BW daily), but there was no difference for steers offered AM/LO or AM/HI (10.7 g/kg of BW). Apparent digestibilities of DM (594 vs. 571 g/kg of intake), NDF (591 vs. 562 g/kg of intake), ADF (585 vs. 566 g/kg of intake), and N (651 vs. 632 g/kg of intake) were greater (P < 0.04) for PM than for AM. Apparent digestibility of N was greater (P = 0.02) for HI (652 g/ kg of intake) vs. LO (631 g/kg of intake). Interactions between harvest and supplement for apparent digestibilities of NDF (P = 0.09) and ADF (P = 0.03) were due to no change or an increase in digestibility in response to increased ruminal degradability of supplement in steers offered PM harvest, whereas increased ruminal degradability of supplement decreased digestibility of NDF and ADF in steers offered AM harvest. Treatments did not affect hay intake (3.93 kg/d), N retained (15.8 g/d), or plasma urea N (5.25 mM) during ad libitum intake. Greater TNC in PM vs. AM harvest was not sufficient by itself to increase total voluntary DMI, but greater protein degradability interacted with harvest time to increase ruminal fiber digestibility and digestible DMI of beef steers offered PM vs. AM harvest.

Urea metabolism in beef steers grazing Bermudagrass, Caucasian bluestem, or gamagrass pastures varying in plant morphology, protein content, and protein composition1,2,3,4

Pastures of Bermudagrass (Cynodon dactylon, BG), Caucasian bluestem (Bothriochloa caucasica, CBS), and gamagrass (Tripsacum dactyloides, GG) were evaluated from the perspectives of forage composition, selection during grazing, and N metabolism in beef steers. All pastures were fertilized with 78 kg/ha of N approximately 60 and 30 d before sample collection. In 2000 and 2001, 12 steers (250 kg of BW) were blocked based on BW and then assigned randomly to a replicated, randomized complete block design, with 2 pastures of each forage and 2 steers per pasture. Three other steers with esophageal fistulas were used to collect masticate samples to represent intake preferences. Herbage mass was >1,900 kg/ha. After at least 14 d of adaptation, urine and blood samples were collected for determination of serum urea N and percentage of urinary N in the form of urea. One steer per pasture (6 steers per year) was infused i.v. with (15,15)N urea for 50 h before collecting urine for 6 h to measure urea N enrichment, urea entry rate, urinary urea excretion, gut urea recycling, and return of urea N to the ornithine cycle. The canopy leaf:stem DM ratio differed (P = 0.01) among BG (0.50), CBS (1.01), and GG (4.00). Caucasian bluestem had less CP (% of DM) than GG or BG in the canopy (9.6 vs. 12.0 or 12.3, P = 0.07) and in the masticate (9.8 vs. 14.7 or 13.9, P = 0.04). Bermudagrass had less true protein (% of CP) than CBS or GG in the canopy (72.9 vs. 83.3 or 83.0, P = 0.07) and in the masticate (73.7 vs. 85.8 or 88.0, P = 0.04). Compared with GG and BG, CBS had less serum urea N (10.1 or 12.2 vs. 2.5 mM, P = 0.01), urea entry rate (353 or 391 vs. 209 mmol of N/h, P = 0.07), and urinary urea excretion (105 or 95 vs. 18 mmol of N/h, P = 0.04), and a greater return of urea N to the ornithine cycle as a proportion of gut urea recycling (0.109 or 0.118 vs. 0.231, P = 0.02). Urea production and recycling in these steers responded more to the N concentration in the grasses than to differences in plant protein fractions. There was no evidence of improved N capture by the steers due to changes in the leaf:stem ratio among the grasses at the herbage mass evaluated.

Afternoon harvest increases readily fermentable carbohydrate concentration and voluntary intake of gamagrass and switchgrass baleage by beef steers12

Our objective was to determine if harvest in the morning (AM, 0600) vs. the afternoon (PM, 1800) affects composition and voluntary DMI of gamagrass (GG) or switchgrass (SG) stored as baleage. Iuka GG (Tripsacum dactyloides L.) and Alamo SG (Panicum virgatum L.) were cut with a mower-conditioner, immediately round-baled, wrapped in plastic, and stored as baleage. Beef steers (255 +/- 7 kg of BW) were assigned (5 steers/treatment) to GG/AM, GG/PM, SG/AM, or SG/PM. Ad libitum intake was measured for 21 d (7-d adjustment and 14-d intake estimate) followed by 7-d adjustment and 5-d digestion and N balance study. Chewing behavior was recorded during the balance study. Compared with AM, PM had more (P < 0.01) starch (9.3 vs. 4.7 g/kg of DM), total nonstructural carbohydrate (30.4 vs. 19.0 g/kg of DM), and monosaccharides (17.1 vs. 11.2 g/kg of DM). Compared with AM, PM had less (P = 0.05) acetate (13.0 vs. 18.6 g/kg of DM) and propionate (0.29 vs. 0.82 g/kg of DM) and tended (P < 0.13) to have less lactate (2.9 vs. 3.5 g/kg of DM) and butyrate (3.9 vs. 5.1 g/kg of DM). Compared with SG, GG had more (P = 0.01) DM (324 vs. 242 g/kg of baleage), CP (114 vs. 97 g/kg of DM), lactate (4.8 vs. 1.6 g/kg of DM), starch (9.4 vs. 4.7 g/kg of DM), total nonstructural carbohydrate (34.2 vs. 15.2 g/kg of DM), and monosaccharides (20.8 vs. 7.4 g/kg of DM). However, GG had a lower (P = 0.01) pH (5.32 vs.5.79) and less (P < 0.01) ethanol (18.7 vs. 27.3 g/kg of DM), acetate (12.3 vs. 19.2 g/kg of DM), propionate (0.00 vs. 1.11 g/kg of DM), and butyrate (0.6 vs. 8.4 g/kg of DM). Daily DMI (2.16 vs. 1.83% of BW) and digestible DMI (1.15 vs. 0.95% of BW) were greater (P = 0.03) for PM than AM. Plasma urea N concentrations at the end of the ad libitum intake phase were greater (P = 0.01) for AM (3.91 mM) than for PM (2.31 mM) and greater (P = 0.07) for GG (3.51 mM) than for SG (2.71 mM). Steers fed PM spent more time eating (P = 0.04) and less time resting (P = 0.01) during meals than steers fed AM. Apparent digestibility of DM and fiber components was not affected (P < 0.18) by treatment. Apparent digestibility and retention of N decreased from PM to AM for SG, but increased for GG (P = 0.05). Retention of N as a percentage of N intake or N digested decreased more from PM to AM for SG than for GG (P < 0.05). We conclude that increased nonstructural carbohydrate content of the PM harvest of these grasses stored as baleage caused increased voluntary intake and improved use of dietary N by beef steers.

Family-based association analysis implicates IL-4 in susceptibility to Kawasaki disease

Several compelling lines of evidence suggest an important influence of genetic variation in susceptibility to Kawasaki disease (KD), an acute vasculitis that causes coronary artery aneurysms in children. We performed a family-based genotyping study to test for association between KD and 58 genes involved in cardiovascular disease and inflammation. By analysis of a cohort of 209 KD trios using the transmission disequilibrium test, we documented the asymmetric transmission of five alleles including the interleukin-4 (IL-4) C(-589)T allele (P=0.03). Asymmetric transmission of the IL-4 C(-589)T was replicated in a second, independent cohort of 60 trios (P=0.05, combined P=0.002). Haplotypes of alleles in IL-4, colony-stimulating factor 2 (CSF2), IL-13, and transcription factor 7 (TCF7), all located in the interleukin gene cluster on 5q31, were also asymmetrically transmitted. The reported associations of KD with atopic dermatitis and allergy, elevated serum IgE levels, eosinophilia, and increased circulating numbers of monocyte/macrophages expressing the low-affinity IgE receptor (FCepsilonR2) may be related to effects of IL-4. Thus, the largest family-based genotyping study of KD patients to date suggests that genetic variation in the IL-4 gene, or regions linked to IL-4, plays an important role in KD pathogenesis and disease susceptibility.

The influence of high-nitrogen forages on the voluntary feed intake of sheep

The objective of this research was to examine the effect of high concentrations of nonprotein nitrogen (NPN) on the voluntary food intake of sheep fed high-quality grasses. Wether lambs (n = 6 per treatment) were fed dried switchgrass (Panicum virgatum L.; Exp. 1) or dried tall fescue (Festuca arundinacea Schreb.; Exp. 2). In both experiments, urea was added to the dried forage at 0 (control), 12, or 24 g of N/kg of DM to increase the NPN concentration. Acid detergent fiber concentrations were 305 g/kg of DM in both experiments, although DM digestibility was 663 and 618 g/ kg of DM in Exp. 1 and Exp. 2, respectively. Voluntary feed intake of the control forage was 28.2 and 19.1 g/ kg of BW in Exp. 1 and Exp. 2, respectively, and decreased for the high-urea treatments to 25.2 and 16.2 g/kg of BW in Exp. 1 (P = 0.07) and Exp 2 (P = 0.03), respectively. Total feed N concentrations increased from 29.5 g to 45.7 g of N/kg of DM in Exp. 1 (P < 0.01) and from 28.4 to 55.9 g of N/kg of DM in Exp. 2 (P < 0.01). Nonprotein N concentrations increased from 28.3 to 53.8% of the total N in switchgrass diets (Exp. 1; P < 0.01), and from 26.4 to 64.0% in tall fescue diets (Exp. 2; P < 0.01). Plasma urea concentrations of the lambs increased from 3.1 to 6.6 mM (Exp. 1; P < 0.01) and from 2.9 to 5.8 mM (Exp. 2; P < 0.01) as the amount of urea added to the diets increased. These changes resulted in an increase in plasma osmolality from 298 to 307 mOsm/kg (Exp. 1; P = 0.04), and from 299 to 307 mOsm/kg (Exp. 2; P = 0.06). Increasing feed N and NPN concentrations through the addition of urea caused a significant decrease in the voluntary feed intake of sheep fed tall fescue and switchgrass. These responses showed no significant cause-and-effect relationship between voluntary feed intake, plasma urea concentrations, and plasma osmolality.

Fermentation of eastern gamagrass (Tripsacum dactyloides [L.] L.) by mixed cultures of ruminal microorganisms with or without supplemental corn1

Five dual-flow fermentors (700 mL) were used to determine the effects of eastern gamagrass (Tripsacum dactyloides [L.] L.) diets on microbial metabolism by mixed rumen cultures. Fermentors were incubated with filtered ruminal contents and allowed to adapt for 4 d to diets followed by 3 d of sample collection. Five dietary treatments were tested: 1) gamagrass hay (GH) + no corn (GHNC), 2) gama grass silage (GS) + no corn (GSNC), 3) GS + low corn (GSLC), 4) GS + medium corn (GSMC); and 5) GS + high corn (GSHC). The experiment was conducted as a randomized complete block design with five treatments and three replications. Total VFA concentrations were not affected by diets. Corn addition linearly decreased (P < 0.001) molar proportion of acetate. In contrast, molar proportion of propionate was reduced in GSLC (cubic effect, P < 0.001) but remained similar across other diets. Corn supplementation linearly increased molar proportion of butyrate (P < 0.001). The acetate + butyrate-to-propionate ratio was highest in cultures offered GSLC (cubic effect, P < 0.001) but similar across other diets. Feeding GSNC resulted in a higher ruminal pH compared with GHNC (P < 0.03). Increasing the level of corn supplementation in GS linearly decreased culture pH (P < 0.001). All diets resulted in similar methane production, with the exception of GSMC, which lowered methane output (quadratic effect, P < 0.004). Total substrate fermented to VFA and gas tended to be greater with GHNC than with GSNC (P < 0.06) and linearly increased with the addition of corn (P < 0.004). Neutral detergent fiber digestibility was similar between GH and GS and was not affected by supplemental corn. Microbial N flow increased in cultures offered GSHC (quadratic effect, P < 0.02). Corn supplementation at the medium and high level linearly decreased C 18:0 (P < 0.02) and increased trans-C18:1 (P < 0.004). Including corn at the high level with GS did not have a detrimental effect on fermentation in dual-flow fermentors.

Kawasaki disease: the mystery continues

Kawasaki disease (KD) is an acute vasculitis of infancy and early childhood that continues to baffle researchers and clinicians alike. Although the acute illness resolves spontaneously, permanent damage to the coronary arteries occurs in 20-25% of untreated children. The cause of KD remains unknown and there is no specific laboratory test to identify affected children. Nonetheless, high dose intravenous g-globulin plus aspirin administered within the first 10 days of fever significantly reduces the risk of coronary artery damage by unknown mechanisms. KD thus presents a unique dilemma: the disease may be difficult to recognize, there is no diagnostic laboratory test, there is an extremely effective therapy, and there is a 25% chance of serious cardiovascular damage or death if the therapy is not administered. This review will highlight some of the many unanswered questions about KD.

Nitrogen metabolism of beef steers fed endophyte-free tall fescue hay: effects of ruminally protected methionine supplementation

Level of nitrogen (N) intake and ruminally protected methionine supplementation were evaluated in eight Angus growing steers (initial BW 253+/-21 kg, final BW 296+/-21 kg) in a replicated 4+/-4 Latin square design. The steers were fed two endophyte-free tall fescue (Festuca arundinacea) hays that contained 2.2 (LO) or 2.8% (HI) of DM as N and were either supplemented or not with ruminally protected methionine (10 g metabolizable methionine/d). Diets were fed to provide adequate energy for 0.5 kg ADG and sufficient protein for maintenance (LO), or protein to support 0.5 kg ADG (HI). Following at least 14 d of adjustment, N balance was measured for 6 d. Isotopic urea was infused (15N15N-urea, 0.164 mmol urea N/h) via a jugular catheter for 56 h and urine was collected from 48 to 56 h to measure urea kinetics. Jugular blood was collected during the balance trial, and serum was analyzed for serum urea N (SUN). By design, daily N intake was greater (P < 0.05) for HI (112 g) than for LO (89 g). Compared with LO, steers when fed HI had greater (P < 0.05) daily DMI (4,217 vs 4,151 g), fecal N (34.4 vs 31.2 g), N digested (77.1 vs 57.7 g), urine N (48.3 vs 37.5 g), urine urea N excretion (34.6 vs 24.8 g), and N retained (29.8 vs 21.1 g). When fed HI steers also had higher (P < 0.05) urine urea N concentration (276 vs 219 mM), SUN (8.7 vs 6.7 mM), N digestibility (69.1 vs 64.9%), percentage of urinary N present as urea (71.5 vs 66.7%, P < 0.053), and rate of urea N production (59.6 vs 49.2 g/d) but lower (P < 0.05) percentage of urea N produced that was returned to the ornithine cycle (15.03 vs 19.2 1%) than when fed LO. Methionine supplementation decreased daily urine N (41.2 vs 44.6 g, P = 0.10) and increased both the amount of N retained daily (27.9 vs 23.7 g, P < 0.089) and the percentage of N digested that was retained (40.4 vs 34.6%, P < 0.094). In summary, supplemental methionine met a specific dietary limitation by increasing the amount of digested N that was retained by the steers.

Sensorineural hearing loss and Kawasaki disease: a prospective study

PURPOSE

Kawasaki disease (KD) is an acute, self-limited vasculitis of infants and children that is now the most common cause of acquired heart disease in the pediatric age group in the United States and Japan. Reports have documented the association of acute KD with sensorineural hearing loss. To assess the prevalence of hearing loss following acute KD in a geographically and ethnically diverse population, a prospective, multicenter study of hearing loss in patients with KD was conducted.

MATERIALS AND METHODS

Patients with acute KD were enrolled in 7 clinical centers and underwent a primary audiologic evaluation within 30 days of the onset of fever. Patients were subsequently reevaluated after resolution of the acute phase of the disease. A questionnaire assessing risk factors for hearing loss was also administered.

RESULTS

A total of 62 patients were evaluated during the 29-month study period. At the first audiologic evaluation, 19 patients (30.6%) had sensorineural hearing loss, 6 patients (9.7%) had conductive hearing loss, 17 patients (27.4%) had normal hearing, and 20 patients (32.3%) had inconclusive studies. Overall, 2 of 36 patients (5.5%) had sensorineural hearing loss documented on their second audiologic evaluation. No risk factors for hearing loss were identified by the questionnaire.

CONCLUSIONS

Transient sensorineural hearing loss (20 to 35 dB) is a frequent complication of acute KD and may be related to salicylate toxicity in some patients. Persistent sensorineural hearing loss is uncommon. Parents and primary care providers should be made aware of the potential for persistent sensorineural hearing loss following resolution of KD, but routine audiologic screening of this patient population does not appear to be warranted.

Urea flux in beef steers: effects of forage species and nitrogen fertilization

The effects of two forage species and N levels on urea kinetics and whole-body N metabolism were evaluated in eight Angus steers (initial BW 217+/-15 kg). In a replicated, 4 x 4 Latin square design, steers were fed gamagrass (Tripsacum dactyloides L.) or switchgrass (Panicum virgatum L.), each of which had 56.2 (LO) or 168.5 (HI) kg of N fertilization per hectare. Diets provided adequate energy for 0.5 kg ADG. Nitrogen balance and urea kinetics were measured from d 22 to 27 of each period. Urine samples collected during intravenous infusion of bis 15N urea were used to calculate production and recycling of urea N from relative abundance of urea isotopomers. Jugular blood serum was analyzed for serum urea N (SUN). Gamagrass differed from switchgrass (P < 0.05) in daily DMI (4,273 vs 4,185 g), N intake (72 vs 67 g), DM digestibility (61.0 vs 63.6%), fecal N (30.6 vs 28.3 g/d), urine urea N (10.5 vs 8.0 g/d), and percentage of urinary N present as urea N (53.5 vs 40.0%). After adjustment for differences in N intake, fecal N still tended to be greater (P < 0.09) for gamagrass than for switchgrass. The LO differed from the HI (P < 0.01) in daily N intake (63 vs 76 g), DM digestibility (61.3 vs 63.3%), urine N (13.6 vs 25.9 g/d), and N retained as a percentage of N digested (57.3 vs 43.5%). Compared to switchgrass, gamagrass had greater SUN, N digestibility, and N digested as N level increased (forage x N level interactions, P < 0.05). As N level increased, N retention increased from 19.5 to 23.5 g/d in gamagrass and decreased from 20.5 to 18.1 g/d in switchgrass (interaction, P < 0.07). The HI group was greater than the LO intake group (P < 0.03) in endogenous production of urea N (44.4 vs 34.0 g/d), gut entry rate of urea N (31.6 vs 28.2 g/d), and the amount of urea N that re-entered the ornithine cycle (9.4 vs 7.9 g/d). However, the percentage of urea N entering the gastrointestinal tract that was recycled was constant among treatments (29.1%), indicating that almost 70% of the urea N that entered the gastrointestinal tract was potentially available for anabolic purposes of the steers as a component of microbial products that were absorbed or excreted in the feces. In summary, N levels affected N metabolism of steers more when they were fed gamagrass than when they were fed switchgrass. Although the absolute amounts of N moving through the system changed with variations in intake, the proportions remained similar, with a greater efficiency of N use at low N intakes.

Hemolymph analysis and evaluation of newly formulated media for culture of shrimp cells (Penaeus stylirostris)

Creation of a shrimp cell line has been an elusive goal. This failure may be due to the composition of the cell culture medium, which may be inadequate to support primary cultured cells. Shrimp hemolymph should contain the nutritional components needed to support cell growth and division. We report here the comprehensive biochemical analysis of hemolymph from the blue shrimp, Penaeus stylirostris (Litopenaeus stylirostris) (see Holthuis, L. B. Shrimps and prawns of the world, in: FAO species catalog. Vol. 1. Rome: Food and Agriculture Organization of the United Nations; 1980), for free amino acids (FAAs), carbohydrates, electrolytes, metals, pH, and osmolality. Levels of hemolymph components were compared to 2xL-15 with 20% fetal bovine serum, a commonly used culture medium for crustacean cells. The FAAs, taurine and proline, and the metals, strontium and zinc, were significantly higher in hemolymph than in the 2 x L-15 medium. In contrast, other FAAs were up to 50 times higher in the 2 x L-15 medium than in the hemolymph. To mimic more closely the hemolymph composition, we created two new media based on either the 0.2 x L-15 or the M199 medium. We compared the microscopic appearance of cells cultured in these media and evaluated deoxyribonucleic acid (DNA) and protein synthesis by 3H-thymidine uptake and 35S-methionine uptake assays. The ovary cells of P. stylirostris cultured in either of the new media formed monolayers, while the cells cultured in 2 x L-15 medium did not. Despite these differences, there was no evidence of sustained DNA or protein synthesis with any of the media. Future studies to establish a shrimp cell line should focus on analysis of the cell cycle and on overcoming the molecular blocks to cell division.

Reporter gene expression in fish following cutaneous infection with pantropic retroviral vectors

A central issue in gene delivery systems is choosing promoters that will direct defined and sustainable levels of gene expression. Pantropic retroviral vectors provide a means to insert genes into either somatic or germline cells. In this study, we focused on somatic cell infection by evaluating the activity of 3 promoters inserted by vectors into fish cell lines and fish skin using pantropic retroviruses. In bluegill and zebrafish cell lines, the highest levels of luciferase expression were observed from the 5' murine leukemia virus long terminal repeat of the retroviral vector. The Rous sarcoma virus long terminal repeat and cytomegalovirus early promoter, as internal promoters, generated lower levels of luciferase. Luciferase reporter vectors infected zebrafish skin, as measured by the presence of viral DNA, and expressed luciferase. We infected developing walleye dermal sarcomas with retroviral vectors to provide an environment with enhanced cell proliferation, a condition necessary for integration of the provirus into the host genome. We demonstrated a 4-fold to 7-fold increase in luciferase gene expression in tumor tissue over infections in normal walleye skin.

Increased frequency of alleles associated with elevated tumor necrosis factor-alpha levels in children with Kawasaki disease

Genetic polymorphisms influence the magnitude of the cytokine response after an inflammatory stimulus. To determine whether such polymorphisms might play a role in Kawasaki disease (KD), we analyzed white and Japanese children with KD and control populations for two polymorphic loci in which the A allele is associated with high tumor necrosis factor-alpha secretion. The lymphotoxin-alpha+250 A/A genotype was overrepresented among white children with KD compared with controls (0.59 versus 0.36; p = 0.013). The tumor necrosis factor-alpha-308 A/G genotype was overrepresented among whites with KD who had coronary artery abnormalities compared with those with normal echocardiograms (0.36 versus 0.09; p = 0.044). No significant difference was seen at either locus between Japanese children with KD and Japanese controls. The increased frequency of the high secretor alleles in white children with KD suggests that these loci may be related to susceptibility to KD and to outcome after disease.

Computer-assisted analysis of the oral brush biopsy

Computer-assisted analysis of the oral brush biopsy is a recently introduced tool that determines the significance of an oral lesion. The oral brush biopsy is minimally invasive, requires no anesthesia, and definitively distinguishes benign from precancerous and cancerous lesions. Oral brush biopsy specimens are analyzed with the aid of a highly specialized neural network-based computer system specifically designed to detect oral epithelial precancerous and cancerous cells.

Kawasaki disease

Kawasaki disease is an acute self-limited vasculitis of infancy and early hildhood that is now the leading cause of acquired heart disease in children in the United States and Japan. An infectious cause is suspected, although the etiology remains unknown. Children typically are seen with the acute onset of fever followed by signs of mucosal inflammation and vasodilatation that evolve over the first week of the illness. Laboratory tests reveal a marked systemic inflammatory response. If untreated, 1 in 4 children will develop permanent damage to the coronary arteries. Intravenous gamma globulin in conjunction with aspirin is effective in reducing the inflammation and preventing coronary artery abnormalities if administered within the first 10 days of illness. This poses a difficult situation for the pediatric care provider who must distinguish Kawasaki disease from other rash/fever syndromes in a timely manner so that appropriate therapy can be initiated.

Preference by sheep and goats among hay of eight tall fescue cultivars

Grazing ruminants use both visual cues and taste in selecting their diet. Preference during grazing may not be the same when forage is dried for hay and cut into lengths prior to feeding in confinement. Eight cultivars of tall fescue (Festuca arundinacea Schreb.), previously evaluated for preference while grazed, were harvested three times over a period of 2 yr. The hays were air-dried, baled, and passed through a hydraulic bale processor prior to feeding. Five experiments were conducted. All three harvests were evaluated with sheep and the last two also with goats, using six animals each time. During an adaptation phase, hays were offered alone as meals. In the experimental phase, every possible pair of hays (28 pairs) was presented for a meal. Data were analyzed by multidimensional scaling and by traditional analyses. Preference was significant among cultivars in all experiments. Multidimensional scaling showed that selection was based on two criteria with two dimensions being significant. Sheep preferred KENHY followed by KENTUCKY 31 and STARGRAZER but preferenced against BARCEL. HIMAG, MO-96, and C1 were intermediate and MOZARK was variable. Goats were similar to sheep in preferring KENHY followed by STARGRAZER and selected against MOZARK and BARCEL. KENTUCKY 31, HIMAG, MO-96, and C1 were intermediate. In all five experiments, the general association was positive for available carbohydrate fractions and negative for fiber fractions that contribute to cell wall rigidity.

Infectious hypodermal and hematopoietic necrosis virus of shrimp is related to mosquito brevidensoviruses

We purified and sequenced infectious hypodermal and hematopoietic necrosis virus (IHHNV), a small DNA virus of shrimp, from wild Penaeus stylirostris. The virion has a buoyant density of 1.45 as determined by cesium chloride gradient. Analysis of 3873 nucleotides of the viral genome revealed three large open reading frames (ORFs) and parts of the noncoding termini of the viral genome. The left, mid, and right ORFs on the complementary (plus) strand have potential coding capacities of 666 amino acids (aa) (75.77 kDa), 363 aa (42.11 kDa), and 329 aa (37.48 kDa), respectively. The overall genomic organization is similar to that of the mosquito brevidensoviruses. The left ORF most likely encodes the major nonstructural (NS) protein (NS-1) since it contains conserved replication initiator motifs and NTP-binding and helicase domains similar to those in NS-1 from all other parvoviruses. The IHHNV putative NS-1 shares the highest aa sequence homology with the NS-1 of mosquito brevidensoviruses, Aedes densovirus and Aedes albopictus parvovirus. A search for putative splicing sites revealed that the N-terminal region of NS-1 is very likely located in a small ORF upstream of the left ORF. The right ORF is presumed to encode structural polypeptides (VPs), as in other parvoviruses. Two putative promoters, located upstream of the left and right ORFs, are presumed to regulate expression of NS and VP genes, respectively. Thus, IHHNV is closely related to densoviruses of the genus Brevidensovirus in the family Parvoviridae, and we therefore propose to rename this virus Penaeus stylirostris densovirus (PstDNV).

Relationship of climate, ethnicity and socioeconomic status to Kawasaki disease in San Diego County, 1994 through 1998

BACKGROUND

Kawasaki disease (KD) is the most common cause of acquired heart disease in children in the United States. By monitoring trends in patient numbers and demographics during a 5-year period, we were able to explore the relationship between climate, ethnicity, socioeconomic status and susceptibility to KD.

METHODS

We conducted active surveillance for all patients hospitalized with KD in San Diego County from 1994 through 1998. Data on seasonal variation in monthly rainfall and temperature were obtained from the US Meteorological Service. Patient sex, age, date of admission and self-reported ethnicity were identified from patient medical records. Socioeconomic status was assessed on the basis of insurance status among patients hospitalized at a single institution.

RESULTS

During the 5-year period there were 169 cases of KD in San Diego County. The overall annual incidence of KD in children < 5 years of age ranged from 8.0 to 15.4/100 000. KD incidence was inversely associated with average monthly temperature (r = -0.47, P < 0.001) and positively associated with average monthly precipitation (r = -0.52, P < 0.001). Asian/Pacific Islanders < 5 years of age were 2.7 times as likely and Hispanics were one-third as likely to be hospitalized for KD than children from all other ethnic groups combined. Children with private or military insurance in all ethnic groups were more likely to have a diagnosis of KD than children with government assistance or no insurance. After controlling for insurance status, only Asian/Pacific Islanders remained at increased risk (rate ratio, 2.14) for KD relative to all other ethnic groups combined.

CONCLUSION

KD is a common childhood vasculitis of unknown etiology. The skewed ethnic distribution and seasonality are consistent with the hypothesis that KD is an infectious disease that is influenced by environmental and genetic factors.

Psoriatic eruption in Kawasaki disease

We describe 10 patients who developed a psoriatic skin eruption during either the acute or convalescent phase of Kawasaki disease. The skin eruption was pustular in 3 patients, but more typical psoriasiform skin lesions were seen in the remaining 7 patients. No patient has yet developed chronic psoriasis.

Kawasaki disease: A brief history

Tomisaku Kawasaki published the first English-language report of 50 patients with Kawasaki disease (KD) in 1974. Since that time, KD has become the leading cause of acquired heart disease among children in North America and Japan. Although an infectious agent is suspected, the cause remains unknown. However, significant progress has been made toward understanding the natural history of the disease and therapeutic interventions have been developed that halt the immune-mediated destruction of the arterial wall. We present a brief history of KD, review progress in research on the disease, and suggest avenues for future study. Kawasaki saw his first case of KD in January 1961 and published his first report in Japanese in 1967. Whether cases existed in Japan before that time is currently under study. The most significant controversy in the 1960s in Japan was whether the rash and fever sign/symptom complex described by Kawasaki was connected to subsequent cardiac complications in a number of cases. Pathologist Noboru Tanaka and pediatrician Takajiro Yamamoto disputed the early assertion of Kawasaki that KD was a self-limited illness with no sequelae. This controversy was resolved in 1970 when the first Japanese nationwide survey of KD documented 10 autopsy cases of sudden cardiac death after KD. By the time of the first English-language publication by Kawasaki in 1974, the link between KD and coronary artery vasculitis was well-established. KD was independently recognized as a new and distinct condition in the early 1970s by pediatricians Marian Melish and Raquel Hicks at the University of Hawaii. In 1973, at the same Hawaiian hospital, pathologist Eunice Larson, in consultation with Benjamin Landing at Los Angeles Children's Hospital, retrospectively diagnosed a 1971 autopsy case as KD. The similarity between KD and infantile periarteritis nodosa (IPN) was apparent to these pathologists, as it had been to Tanaka earlier. What remains unknown is the reason for the simultaneous recognition of this disease around the world in the 1960s and 1970s. There are several possible explanations. KD may have been a new disease that emerged in Japan and emanated to the Western World through Hawaii, where the disease is prevalent among Asian children. Alternatively, KD and IPN may be part of the spectrum of the same disease and clinically mild KD masqueraded as other diseases, such as scarlet fever in the preantibiotic era. Case reports of IPN from Western Europe extend back to at least the 19th century, but, thus far, cases of IPN have not been discovered in Japan before World War II. Perhaps the factors responsible for KD were introduced into Japan after the World War II and then reemerged in a more virulent form that subsequently spread through the industrialized Western world. It is also possible that improvements in health care and, in particular, the use of antibiotics to treat infections caused by organisms including toxin-producing bacteria reduced the burden of rash/fever illness and allowed KD to be recognized as a distinct clinical entity. Itsuzo Shigematsu, Hiroshi Yanagawa, and colleagues have conducted 14 nationwide surveys in Japan. These have indicated that: 1) KD occurred initially in nationwide epidemics but now occurs in regional outbreaks; 2) there are approximately 5,000 to 6,000 new cases each year; 3) current estimates of incidence rates are 120 to 150 cases per 100,000 children <5 years old; 4) KD is 1.5 times more common in males and 85% of cases occur in children <5 years old; and 5) the recurrence rate is low (4%). In 1978, David Morens at the Centers for Disease Control and Prevention published a case definition based on Kawasaki's original criteria. The Centers for Disease Control and Prevention developed a computerized database in 1984, and a passive reporting system currently exists in 22 states. Regional investigations and national surveys suggest an annual incidence of 4 to 15 cases per 100 000 children <5 years o

Intake and chewing behavior of steers consuming switchgrass preserved as hay or silage

Effect of preservation method on intake and chewing behavior was examined using a first, late vegetative harvest (mid-June) of Kanlow switchgrass (Panicum virgatum L.). For silage (S), forage was harvested with a commercial field chopper (1.5 to 4 cm average chop length) and ensiled directly in silos 1.2 m in diameter and 3.6 m in height. For hay (H), forage was harvested with a flail-chopper (7 to 15 cm average chop length) and cured as hay in a drier at 77 degrees C. Diets of H and S were fed to six Hereford steers (338+/-5 kg) in a single crossover experiment. Chewing behavior was monitored for 4 d with a computerized system. At feeding, H was higher in DM and contained greater concentrations (DM basis) of NDF, CP, and hemicellulose, but lower concentrations of ADF and cellulose, and had lower in vitro DM disappearance values. Steers fed S had higher intakes of DM (P < .02) and NDF (P < .04) and consumed less water from the water supply (P < .01) than animals fed H. However, total amount of water (from water supply and feed) consumed per kilogram of DMI did not differ between diets. Crude protein intake was similar between diets. Preservation method had no effect on eating time, number of boli ruminated, bolus duration, and number of rumination chews per bolus. Steers fed S made fewer eating chews (P < .10) and ruminated for a longer time (P < .05) while making a greater number of rumination chews (P < .04) than steers fed H. Rumination intercycle time was slightly shorter in steers fed H (P < .05) than in steers fed S. When expressed per kilogram of NDF intake, steers fed S spent less time eating (P < .03) and made fewer eating chews (P < .02) than steers fed H; however, rumination time, number of rumination chews, and number of boli ruminated were not affected by preservation method. Steers fed S ingested feed at a greater rate (P < .03), excreted smaller fecal particles (P < .03), had meals of shorter duration (P < .06), spent less time eating during main meals (meals following feed distribution: P < .05), had more rumination periods (P < .01), and a shorter morning (P < .06) latency time (interval between end of main meal and onset of rumination) than steers fed H. These results indicate that preservation method with its concomitant differences in chop length affected forage chemical composition and voluntary intake, and that differences in chewing behavior occurred mostly during eating.

Infection of cultured embryo cells of the pacific oyster, Crassostrea gigas, by pantropic retroviral vectors

The inability to stably introduce and express foreign genes has hampered basic research in molluscan species. We cultured cells from dissociated embryos of the Pacific oyster, Crassostrea gigas, and infected these primary cultures with pantropic retroviral vectors containing the envelope glycoprotein of vesicular stomatitis virus. Luciferase transgene expression mediated by different heterologous promoters was demonstrated for at least 9 d after infection of the cells. Surprisingly, the promoter reproducibly mediating the highest level of luciferase expression was the retroviral promoter (U3 region of long terminal repeat) from the Moloney murine leukemia virus. The infection efficiency using a low multiplicity of infection (0.05) was estimated by quantitative polymerase chain reaction to be between 0.1-0.5%. This system will facilitate studies of gene expression and regulation and should be widely applicable to other molluscan species.

Abnormal myocardial mechanics in Kawasaki disease: rapid response to gamma-globulin

BACKGROUND

The time course and rate of recovery of myocardial dysfunction in association with Kawasaki disease in response to intravenous gamma-globulin is unknown and may provide mechanistic clues.

METHODS AND RESULTS

The acute changes in myocardial contractility in 25 patients with Kawasaki disease were evaluated by noninvasive stress-shortening and stress-velocity analysis. Echocardiograms were performed before and then daily for 4 days during which the patients received gamma-globulin 1.6 to 2 g/kg. Before treatment, contractility was abnormally low (<2 SD) in 14 patients (56%). Contractility increased significantly (2 SD increase) in 17 (68%), including 13 of 14 with depressed contractility and 4 whose initial contractility fell within normal limits. Of the 14 patients with depressed contractility, 8 (57%) normalized within 24 hours and a further 5 (35.7%) normalized within 6 months. A clinical response to treatment (fall in C-reactive protein by 50% and/or resolution of fever within 4 days) was seen in 22 patients (88%). Contractility increased in 17 of the 22 clinical responders and was normal before therapy in the other 5. The 3 patients who did not respond clinically also had no change in contractility with gamma-globulin therapy. Long-term (more than 12 months) follow-up was available in 19 patients. All patients had normal contractility at late follow-up.

CONCLUSIONS

More than half the patients with Kawasaki disease have abnormal contractility at presentation. Myocardial response to gamma-globulin therapy is associated with rapid improvement in myocardial mechanics, with a high concordance between the clinical and myocardial response to therapy. The speed of recovery suggests that depressed contractility in patients with Kawasaki disease is caused by a rapidly reversible process such as circulating toxins or activated cytokines. Long-term outcome is good even in those patients with slow recovery of myocardial function.

Lack of association between Kawasaki syndrome and Chlamydia pneumoniae infection: an investigation of a Kawasaki syndrome cluster in San Diego County

BACKGROUND

The etiology of Kawasaki syndrome (KS), the leading cause of acquired coronary artery disease in children, is unknown. Recent studies have suggested that Chlamydia pneumoniae, a common respiratory pathogen associated with an increased risk of heart disease, might lead to KS.

OBJECTIVE

To assess whether KS was associated with an elevated risk of having a current or antecedent infection with C. pneumoniae.

METHODS

Blood, urine and pharyngeal specimens from KS patients in San Diego County, CA, during a period of high KS incidence were analyzed for evidence of recent C. pneumoniae infection by culture, PCR and serology. Specimens collected from two control groups, family members of KS patients and age-matched children attending outpatient clinics for well child visits, were similarly analyzed.

RESULTS

Thirteen cases were identified. Forty-five outpatient controls and an average of three family members per patient were enrolled in the study. All specimens tested negative for the presence of C. pneumoniae by PCR and culture except for one blood specimen from the mother of a case-patient. Serologic analysis of patients and a subset of outpatient and family controls revealed no evidence of current C. pneumoniae infection; 4 of 13 adult family controls had IgG titers consistent with past exposure to C. pneumoniae. Case patients were no more likely than outpatient controls to have had a respiratory illness in the preceding 2 months (11 of 13 patients vs. 35 of 45 controls; odds ratio, 1.57; 95% confidence interval, 0.3 to 11.9).

CONCLUSIONS

We found no evidence that C. pneumoniae infection was associated with KS.

Kawasaki disease

Kawasaki disease is a leading cause of acquired heart disease in children in the USA. An acute vasculitis of unknown etiology, it occurs predominantly in infancy and early childhood, and more rarely in teenagers. Coronary artery aneurysms or ectasia develop in approximately 15-25% of children with the disease. Treatment with intravenous gamma globulin, 2 g per kg, in the acute phase reduces this risk three- to fivefold. Angiographic resolution occurs in approximately one-half of aneurysmal arterial segments, but these show persistent histologic and functional abnormalities. The remainder continue to be aneurysmal, often with development of progressive stenosis or occlusion. The worst prognosis occurs in children with so-called 'giant aneurysms', i.e. those with a maximum diameter greater than 8 mm, because thrombosis is promoted both by sluggish blood flow within the massively dilated vascular space and by the frequent development of stenotic lesions. Serial stress tests with myocardial imaging are mandatory in the management of patients with Kawasaki disease and significant coronary artery disease to determine the need for coronary angiography and transcatheter interventions or coronary bypass surgery. Continued long-term surveillance in patients with and without detected coronary abnormalities is necessary to determine the natural history of Kawasaki disease.

Actinic cheilitis: a review of 152 cases

OBJECTIVE

The purpose of this study was to determine whether any clinical or histopathologic variables are associated with the severity of epithelial change in lesions of actinic cheilitis.

STUDY DESIGN

A total of 152 acceptable cases of actinic cheilitis were identified from 66,067 cases accessioned from February 1989 to June 1998. For each case, the clinical information supplied by the submitting practitioner at the time of the biopsy and 8 histopathologic variables were evaluated.

RESULTS

The following 5 histopathologic variables were positively correlated with an increased degree of epithelial change: acanthosis, basophilic change within the connective tissue, the presence of inflammation within the connective tissue, perivascular inflammation, and thickness of the keratin layer. None of the clinical variables was associated with an increased degree of epithelial change.

CONCLUSIONS

The presence of any of the aforementioned histopathologic changes should prompt a close evaluation of the lesion for the presence of either epithelial dysplasia or carcinoma.

Pantropic retroviral vectors mediate gene transfer and expression in Entamoeba histolytica

Transformation of Entamoeba histolytica has been previously reported, but the foreign genes have all been replicated episomally. Pantropic retroviral vectors based on the Moloney murine leukemia virus with the envelope glycoprotein of vesicular stomatitis virus (VSV-G) have an extremely broad host range and can be concentrated to high titer. To investigate whether these pseudotyped, pantropic vectors can mediate gene transfer and expression in E. histolytica, we constructed a retroviral vector, in which a hygromycin phosphotransferase is expressed from the E. histolytica actin promoter. Data confirm the infection, integration, and expression of a foreign gene mediated by the provirus. To our knowledge, this is the most evolutionarily distant example of successful integration and expression of a mammalian retrovirus. Pantropic retroviral vectors may thus facilitate genetic analysis in species lacking transformation systems.

Prevention and detection of lip cancer--the dentist's role

With their attention to the oral area, dentists are in an excellent position not only to diagnose lip cancer, but also to counsel patients in its prevention. Patients need to be educated on the dangers of ultraviolet radiation and the measures available to decrease exposure to it. This article discusses the circumstances that increase the chance of developing lip cancer, the variety of ways to decrease that chance, and the recognition and treatment of premalignant and malignant lip lesions.

Variation in ruminants' preference for tall fescue hays cut either at sundown or at sunup

Plants vary diurnally in concentrations of nonstructural carbohydrates. If ruminants prefer forages with higher total nonstructural carbohydrates (TNC), then the preference for hays harvested within the same 24-h period may vary. An established field of tall fescue (Festuca arundinacea Schreb.) was harvested six times in the vegetative stage. Harvests were paired such that each cutting at sundown (PM) was followed by a cutting the next morning at sunup (AM). We harvested in this manner three times, resulting in six hays. The hays were field-dried, baled, and passed through a hydraulic bale processor prior to feeding. Experiments were conducted with sheep, goats, and cattle, using six animals in each case. During an adaptation phase, hays were offered alone as meals. In the experimental phase, every possible pair of hays (15 pairs) was presented for a meal. Data were analyzed by multidimensional scaling and by traditional analyses. Multidimensional scaling indicated that selection was based on a single criterion. Preference for PM hays was greater than for AM hays (P < .01) in all experiments. Increased preference was associated with increased TNC (P < .01) and in vitro true DM disappearance (P < .01) and decreased fiber concentration (P < .01; NDF, ADF, cellulose, and ADL). Mowing hay late in the day was effective in increasing forage preference.

Intravenous gamma-globulin treatment and retreatment in Kawasaki disease. US/Canadian Kawasaki Syndrome Study Group

OBJECTIVE

To determine the prevalence and outcome of intravenous gamma-globulin (IVIG) retreatment in patients with Kawasaki disease (KD).

METHOD

Multicenter, retrospective survey of all children with KD evaluated at nine clinical centers across North America during a 15-month period.

RESULTS

Data were available for 378 patients. At 48 h after completion of the initial IVIG infusion, 50 patients (13.2%) remained febrile, 29 (58.0%) of whom were retreated with IVIG, including 4 (13.8%) with coronary artery abnormalities before their first IVIG infusion. Among 25 retreated patients with a normal baseline echocardiogram, 5 (20.0%) developed coronary abnormalities and were termed "treatment failures." Among the 323 patients with a normal baseline echocardiogram, only 9 (2.8%) were treatment failures; treatment failure occurred in 4 of 282 (1.4%) patients who became afebrile post-IVIG and in 5 of 41 (12.2%) patients with persistent or recrudescent fever after their first course of IVIG therapy (P=0.002).

CONCLUSIONS

The overall prevalence of new coronary abnormalities in KD patients treated with IVIG and aspirin remains low. Persistent or recrudescent fever after the first course of IVIG was associated with an increased risk of treatment failure (P=0.002). IVIG retreatment in patients who remain febrile after the first course of IVIG is now common (58.0%), although the efficacy of this practice requires assessment with a randomized trial.

Transgenic cattle produced by reverse-transcribed gene transfer in oocytes

A critical requirement for integration of retroviruses, other than HIV and possibly related lentiviruses, is the breakdown of the nuclear envelope during mitosis. Nuclear envelope breakdown occurs during mitotic M-phase, the envelope reforming immediately after cell division, thereby permitting the translocation of the retroviral preintegration complex into the nucleus and enabling integration to proceed. In the oocyte, during metaphase II (MII) of the second meiosis, the nuclear envelope is also absent and the oocyte remains in MII arrest for a much longer period of time compared with M-phase in a somatic cell. Pseudotyped replication-defective retroviral vector was injected into the perivitelline space of bovine oocytes during MII. We show that reverse-transcribed gene transfer can take place in an oocyte in MII arrest of meiosis, leading to production of offspring, the majority of which are transgenic. We discuss the implications of this mechanism both as a means of production of transgenic livestock and as a model for naturally occurring recursive transgenesis.

Infection of lepidoptera with a pseudotyped retroviral vector

Studies requiring the introduction and expression of manipulated gene constructs have been technically difficult in non-drosophilid insects. Retroviruses can be engineered to be replication defective and to serve as vectors for gene constructs of interest. In this study, pseudotyped MoMLV(VSV-G) retroviral vectors are shown to successfully infect lepidopteran cells in vitro and in vivo. In Spodoptera frugiperda cells in vitro and in Manduca sexta in vivo, infection and conversion to proviral DNA were confirmed by PCR amplification and Southern blot hybridization of vector-specific sequences. Gene expression and integration of proviral DNA were also documented in vitro. This is the first report of retroviral infection in lepidoptera and suggests that pseudotyped retroviral vectors could be powerful tools in gene manipulation studies of non-drosophilid insects.

Pantropic retroviral vectors mediate somatic cell transformation and expression of foreign genes in dipteran insects

The control of insects that transmit disease and damage crops has become increasingly difficult. The ability to genetically engineer insects would facilitate strategies to protect crops and block arthropod vector-borne disease transmission. Transformation vectors based on insect transposable elements have been developed, but most have limited host ranges. A promising alternative is the pantropic retroviral vector, which is packaged with the envelope glycoprotein from vesicular stomatitis virus and is replication-defective. We show here that pantropic murine retroviral vectors can mediate high-level expression of foreign genes in somatically transformed insect larvae and adults of three dipteran genera. This success demonstrates the potential for germline transformation mediated by pantropic retroviral vectors.

Cerebrospinal fluid profile in patients with acute Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is an acute vasculitis of infancy and early childhood for which there is currently no diagnostic test. The clinical presentation of KD may initially resemble other infectious diseases, including bacterial or viral meningitis. For this reason lumbar puncture (LP) is sometimes performed during the evaluation of these patients. To understand the range of cerebrospinal fluid (CSF) changes that may be associated with acute KD, a retrospective review of unselected KD patients from three pediatric centers was performed.

METHODS

Retrospective chart review was performed on KD patients evaluated during the first 10 days of illness who had an LP performed before the administration of intravenous gamma-globulin.

RESULTS

During the 6.5-year study period, 46 KD patients underwent LP as part of their clinical evaluation. Of these patients 18 (39.1%) had CSF pleocytosis, 1 (2.2%) had a CSF glucose <45 mg/dl and 8 (17.4%) had an elevated CSF protein. Of the patients with CSF pleocytosis, the median white blood cell count was 22.5 cells (range, 7 to 320 cells), with a median of 6.0% neutrophils (range, 0 to 79%) and 91.5% mononuclear cells (range, 11 to 100%).

CONCLUSIONS

In the present series approximately one-third of KD patients who underwent an LP had CSF pleocytosis with a mononuclear cell predominance. No patient had significant hypoglycorrhachia, and elevation of the CSF protein was uncommon. CSF abnormalities were similar between US and Japanese KD patients. The basis for the CSF pleocytosis in acute KD patients remains unknown.

The use of exfoliative cytology for the early diagnosis of oral cancers: is there a role for it in education and private practice?

BACKGROUND

Early detection of oral cancers is not easy, because oral precancerous lesions and early oral cancers can mimic many benign conditions in the mouth, leading to delays in diagnosis and treatment. There is a need to emphasize the early diagnosis of oral cancers in order to reduce the unacceptably high morbidity and mortality.

METHODS

A survey regarding oral exfoliative cytology was completed by 132 dentists in Virginia who were randomly chosen from a mailing list.

RESULTS

Less than half of the dentists (41.7%) had been taught how to obtain a cytologic smear, and only 26.0% knew the clinical indications for doing so. Only 9.2% of the dentists had ever obtained a cytologic smear in private practice. Of the 13 dentists in the survey who had done so, 12 had been trained in the technique. Interest in learning the cytologic technique and getting the needed supplies was indicated by 79.2% of the dentists.

CONCLUSIONS

Diagnostic aids in the evaluation of oral mucosal lesions can serve an important role by identifying lesions that need to be biopsied in spite of a "benign" appearance. Exfoliative cytology, as well as vital staining, may aid in this goal. This has implications regarding undergraduate and postdoctoral education.