Relative value of the inion and mid-parietal locations as additional recording sites in pattern reversal visual evoked potentials.

Although the P100 response of pattern reversal visual evoked potentials (PRVEPs) is most commonly recorded from the midline occipital site (MO), the response at this location can occasionally be absent or poorly defined due to anatomical variability of the visual cortex. In these cases, the American Electroencephalographic Society Evoked Potential Guidelines recommends recording from the mid-parietal (MP) and Inion electrode sites. In this study, we compared the amplitude of the P100 component recorded simultaneously from MO, MP and the Inion. PRVEPs obtained following stimulation with 30' check sizes from 155 consecutive patients (310 eyes) over a 2 year period were analyzed. At each of the 3 recording sites, the peak amplitude of P100 was calculated as N75-P100, P100-N145, and the sum of N75-P100 and P100-N145. There was a statistically significant difference between the electrode sites for all 3 methods of amplitude measurement (one-way ANOVA; P < 0.0001). For each method of measurement, there was no significant difference between P100 amplitude at MO or the Inon, but a significantly reduced amplitude at MP compared to both the MO and Inion electrode sites (post hoc Scheffe, P < 0.05). The P100 amplitude was highest at the Inion in 18% of responses, including cases where the amplitude at that site was at least twice that at MO. In no case was the amplitude highest at MP. Our results indicate that the Inion is a better recording site compared to MP when acquiring PRVEPs, is often complementary to MO, and should be the first additional site to be used when extra channels are available.

Correlation of evoked potential and MRI findings in Wilson's disease.

We recorded brainstem auditory evoked potentials (BAEPs) and somatosensory evoked potentials to median nerve stimulation (MSEPs) within 10 days of brain MRI in 20 patients with Wilson's disease (WD). MRI was abnormal in 90% of patients, demonstrating symmetric striatum and brainstem lesions with or without thalamic lesions. MSEPs were abnormal in 65% of patients, usually showing bilaterally prolonged N/P13-N20 latencies. BAEPs were abnormal in 40%, most often with bilateral prolongation of the III-V latency. The III-V and N/P13-N20 interpeak latencies correlated significantly with the severity of MRI lesions in the caudal pons, rostral pons, and caudal midbrain. Our results indicate that subclinical sensory dysfunction is common in WD, and that auditory and somatosensory pathways are most severely affected at the brainstem level. Both the localization and severity of evoked potential abnormalities correspond closely to the morphologic changes in the pons and caudal midbrain shown by MRI.

Potential role of Proteus-Providencia-Morganella species in quality deterioration of beef.

Proteeae Isolation Medium of Hawkey et al. (1986) was effective for isolation and enumeration of Proteus-Providencia-Morganella spp. from beef and beef products. On this medium colonies were brown, surrounded by a zone of clearing. In an examination of retail beef samples packaged and stored in polyvinyl chloride (PVC) film, 5% contained these bacteria in a concentration of 10(1)-10(2) cells per gram or cm(2). Isolates from retail beef samples included P. vulgaris, P. alcalifaciens, P. rettgeri, and M. morganii. None of the retail samples packaged and stored in high oxygen barrier (HOB) film contained detectable Proteus-Providencia-Morganella spp. Steaks inoculated with Proteus-Providencia-Morganella spp. and packaged and stored at 4°C in PVC film (15 days) or in HOB film (42 days) usually had a reduced count of Proteus-Providencia-Morganella spp. during storage. Slight increases in counts occurred on steaks inculated with P. vulgaris and P. rettgeri and stored at 4°C for 15 days in PVC film.

Identification and evaluation of volatile compounds of vacuum and modified atmosphere packaged beef strip loins.

Beef strip loins were packaged and stored for up to 28 days at 3°C in high-oxygen barrier film under vacuum and in 100% CO(2), 40% CO(2)/60% N(2) and 20% CO(2)/80% O(2). As storage progressed, loins packaged and stored in 20% CO(2)/80% O(2) developed strong off-odors. 1-hexene, methyl thiirane, ethyl acetate, benzene and 1-heptene were detected in these packaged loins beginning at 7 to 14 days of storage. With the exception of 1-hexene, these compounds were not consistently detected in loins stored in vacuum, in 100% CO(2), or in 40% CO(2)/60% N(2), and these packaged loins developed much less off-odor during storage than loins packaged and stored in 20% CO(2)/80% O(2). A large number of volatile compounds from the headspace of the packaged loins originated from the packaging material. Lactobacillus plantarum became the dominant flora on loins stored under vacuum and under 40% CO(2)/60% N(2) while Leuconostoc mesenteroides subsp. mesenteroides predominated in loins stored in 100% CO(2). Pseudomonas putida eventually dominated on loins stored in 20% CO(2)/80% O(2).

Polarity reversal of N20 and P23 somatosensory evoked potentials between scalp and depth recordings.

From depth and scalp electrodes, we recorded MN-SSEPs of a 33-year-old man with right parietal dysfunction and refractory right temporal seizures. A depth lead with 8 electrodes was implanted deep in each parietal-temporal region. Stimulation and recording parameters followed American EEG Society guidelines. Scalp recordings had well-defined P9, P13-14, N18, N20, and P23 potentials with normal conduction times bilaterally. Depth recordings showed potentials of greater number, voltage, and coherence. P13-14 and N18 were recorded at all depth sites with latencies similar to those at the scalp. N18 had markedly greater voltage and duration near the thalamus, with multiple fast components on its ascending phase. In the deep parietal region there was a positivity corresponding to the scalp N20 and a negative potential equal in latency to scalp P23. These findings support an origin of P13-14 caudal to the thalamus, multiple thalamic and possibly rostral brain-stem generators for N18, and generation of N20 and P23 in sensory cortex of subjacent white matter.

Multimodality evoked potential testing in acute mild closed head injury.

Multimodality evoked potential (MEP) testing, including brainstem auditory, visual, and somatosensory evoked potentials, have been reported to be useful in predicting outcome in severe closed head injury. Brainstem auditory evoked potentials have been demonstrated to be abnormal in 10% to 40% of acute mild head injury. A prospective study of 18 patients with mild closed head injury was undertaken to determine the usefulness of MEP screening within two weeks of the acute event. Long latency event-related potentials (P300s), in response to auditory stimuli with an oddball paradigm, were included in the screening. The subjects had several symptoms consistent with the postconcussive syndrome at the time of the evoked potential testing. Only one patient had an abnormal evoked potential response (greater than three standard deviations from the mean) from all the testing done. The standard methods of MEP testing were insensitive to quantifying the possible physiologic changes that are associated with memory deficits, lethargy, and emotional irritability after mild closed head injury.

Effect of Degree of Sanitation From Slaughter Through Fabrication on the Microbiological and Sensory Characteristics of Beef.

Steers were slaughtered, dressed, and fabricated using conventional procedures or strict sanitary procedures. Strict sanitary procedures involved antemortem washing of steers, use of disposable gloves, careful handling of carcasses to prevent cross-contamination, and spraying of carcasses with hot (55°C) 1% L-lactic acid before evisceration and before entering the chill cooler. Mean aerobic plate counts (APC, log10/cm2) of carcasses slaughtered under strict sanitary conditions and of subprimals (boneless strip loins and ribs) from animals handled under strict sanitary conditions and stored at 1°C in high-oxygen barrier (HOB) film (0 to 80 d) were lower than those of carcasses and subprimals from animals slaughtered and fabricated using conventional procedures. In most cases, APCs of steaks displayed in polyvinyl chloride (PVC) film for 0 to 6 d from animals and subprimals handled under strict conditions were lower than those of steaks from animals and subprimals handled under conventional procedures. Bacillus spp., Micrococcus spp., and yeasts were the dominant (50% or more of microflora) microbial types on carcasses that were slaughtered and dressed using strict sanitary conditions. For carcasses slaughtered using conventional procedures, Micrococcus spp. and to a lesser extent Streptococcus , coagulase-negative Staphylococcus and/or coryneform bacteria were the dominant microbial types. After 20 d of storage, there were no consistent differences in the percentage distribution of microbial types on the two groups of subprimals. Lactobacilli dominated the microflora of subprimals at that time. When scores for lean color, surface discoloration, fat color, overall appearance, and odor of steaks from subprimals handled under strict sanitary conditions were significantly different (P<0.05) from controls, treated steaks were more desirable than those of comparable steaks from control subprimals.

Multiple intracerebral hemorrhages after smoking "crack" cocaine.

After smoking "crack" cocaine and consuming large quantities of ethanol, a 36-year-old man developed multiple, bilateral, deep, and superficial cerebral hematomas. He was hypertensive for several days, but angiography revealed no evidence of vascular malformation or vasculitis. The multifocality of the hematomas and lack of underlying disease suggest that the hemorrhages resulted from cocaine-induced acute hypertension or arterial spasm, possibly potentiated by heavy ethanol consumption.

Microbiological characteristics of pork chops and ground pork from swine fed a high monosaturated fat diet.

Twelve percent high-oleic acid sunflower oil (HOSO) was included in a swine diet to increase the ratio of monounsaturated fatty acids to saturated fatty acids in pork chops and ground pork patties. Aerobic plate counts (APCs) of pork chops prepared from animals on control and HOSO diets did not differ (P >0·05) and no specific pattern of differences in the microflora of pork chops or ground pork patties could be attributed to diet. However, after 4 days of refrigerated storage, APCs of ground pork patties from animals fed the HOSO diet were lower (P<0·05) than those of comparable patties prepared from animals fed the control diet.

Somatosensory evoked potentials of the dog: recording techniques and normal values.

Median and tibial nerve somatosensory evoked potentials (SSEPs) of 5 sedated dogs were studied to determine their normal features and optimal stimulation and recording techniques. Cortical potentials were mapped from an extensive array of skull electrodes as each limb was independently stimulated with subdermal needles. The effects of bandpass and stimulus intensity and rate were also assessed. Three cortical components (P1, N1, P2) were evoked by median or tibial nerve stimulation and were localized along the coronal suture at lateral and medial electrodes, respectively. SSEP voltage varied much more than morphology, topography, or latency. The inion was a stable, indifferent reference site. Cortical SSEP frequency content was mostly below 250 Hz. Maximal SSEP voltage was achieved only at stimulus intensities 2-3 times motor threshold. Appropriate methods minimize technical difficulties and consistently yield legible SSEPs.

Ictal cortical blindness with permanent visual loss.

Cortical blindness is rarely an ictal manifestation. We report the case of a man who developed transient cortical blindness followed by permanent visual deficits during repeated partial seizures. Intermittent visual impairment began at age 14 years. After he had the first generalized seizure at age 28 years, neurologic, ophthalmologic, angiographic, and brain computed tomographic (CT) examinations were normal. Several EEGs showed almost continuous biposterior spike-waves. Over the next several years, frequent partial seizures were associated with transient visual loss and left body twitching or paresthesias. When he was 32, transient blindness occurred during several days of repeated occipital seizures. Permanent left homonymous hemianopia, right homonymous central scotoma, dyschromatopsia, and altered stereopsis followed these seizures. Brain CT demonstrated a new right occipital lesion. Partial seizures arising posteriorly may cause transient cortical blindness and result in permanent visual deficits.

Microbiological characteristics of precooked, vacuum-packaged uncured beef and pork.

Microbiological examination of 29 packages of precooked, vacuum-packaged beef and pork products purchased at local and regional supermarkets along with 110 packages of precooked, vacuum-packaged, sliced roast beef obtained from a major meat processor did not disclose the presence of Escherichia coli, coagulase-positive Staphylococcus aureus, Clostridium perfringens or Salmonella. The effects of storage temperature and length of storage on the microflora of 110 packages of sliced roast beef were determined at specific intervals of storage up to 84 days at 1° and 5°C, and up to 28 days at 10°C. The microflora of samples stored at 1° and 5°C was dominated by Lactobacillus spp. when examined on day 28 and throughout the remainder of the 84-day test period. The microflora of samples held at 10°C was dominated by Lactobacillus spp. until late in storage when Hafnia alvei became a major portion of the bacterial population. Precooked, sliced roast beef had a longer shelf life in laboratory controlled evaluations when stored at 1°C as opposed to 5° or 10°C.

Isolated small-vessel angiitis of the central nervous system.

Isolated cerebral angiitis was confirmed by brain parenchyma biopsy in a 31-year-old man with a rapidly progressive encephalopathy and normal cerebral angiography and magnetic resonance imaging. Presenting features of aphasia, hemiparesis, and lethargy resembled herpes simplex encephalitis. Severe neurologic deficits rapidly resolved with steroids plus cyclophosphamide, and he remains in remission after two years. This case illustrates potentially misleading early manifestations of isolated cerebral angiitis, diagnostic limitations of angiography, the value of biopsy that includes both brain parenchyma and leptomeninges, and the potential efficacy of steroid and cyclophosphamide therapy in small-vessel disease. Clinical features and response to treatment vary widely in reported cases, suggesting that isolated cerebral angiitis may have diverse etiologies.

Retail Case-Life and Microbial Quality of Pre-Marinated, Vacuum Packaged Beef and Chicken Fajitas.

Thirty packages (454 g) each of beef and chicken pre-marinated vacuum packaged fajitas were obtained from a commercial meat purveyor and placed in a retail case for 16 d. At days 1, 5, 9, 12 and 16, aerobic plate counts (APCs) and microbial types of three randomly selected samples of each product were determined. Samples were also evaluated for surface discoloration, overall appearance, immediate and cooked off-odor and off-flavor. As storage progressed, the pH of products declined, APCs increased and Lactobacillus spp. Became dominant in the microflora. Some packaged fajitas, especially chicken, exhibited gas formation in random packages throughout the storage periods. Products became "unacceptable" between 12 and 16 d of retail storage.

Microbiological Characteristics and Shelf Life of Corn Tortillas with and without Antimicrobial Agents.

Commercial corn tortillas were assayed for pH, moisture, aw, aerobic plate count (APC) and mold and yeast count (MYC). The shelf life of commercial tortillas ranged from 3 to 60 days, depending on the amount and type of preservative added. High initial APCs of commercial tortillas were associated with poor sanitary conditions at the plants, airborne contamination and improper storage practices. Shelf life of tortillas was greatly enhanced by refrigerated storage with or without the use of antimicrobials. For tortillas stored at 25°C, substantial increases in shelf life were attained by acidification (0.45% fumaric acid) plus addition of K-sorbate or Ca-propionate, but particularly by combination of these two antimicrobials. For tortillas stored at 4°C, shelf life of non-acidified samples was somewhat enhanced by addition of parabens and combinations of K-sorbate and Ca-propionate. Shelf life of acidified tortillas at 4°C was somewhat enhanced by addition of parabens and K-sorbate but increased substantially by addition of Ca-propionate and combinations of K-sorbate and Ca-propionate.

Microbiological and sensory characteristics of pork loin chops: Role of intramuscular fat.

Pork loin chops of High, Intermediate and Low intramuscular fat were trimmed free of subcutaneous fat and then packaged and stored in polyvinyl chloride (PVC) film for 0-6 days or in high oxygen barrier (HOB) film for 0-28 days at 4°C ± 1°C. In general, marbling group had no (P > 0·05) effect on the aerobic plate count (APC) and did not result in major differences in the distribution of types in the microflora of pork loin chops. During storage, Pseudomonas spp. became dominant in the microflora of PVC-wrapped chops while Lactobacillus spp. became dominant in the microflora of chops stored in HOB film. Of the sensory characteristics examined, mean surface discoloration and mean overall appearance scores of chops of Low intramuscular fat stored in HOB film were usually lower (P < 0·05) than those of chops of Intermediate and High intramuscular fat. In contrast, marbling group usually had no significant effect on mean surface discoloration and mean overall appearance scores of chops packaged in PVC film.

Microbiological and sensory characteristics of pork loin chops: Role of subcutaneous fat.

Pork loin chops with the subcutaneous fat attached, without subcutaneous fat and the subcutaneous fat that was removed from chops were packaged and stored at 4°C±1°C in polyvinyl chloride (PVC) film for 0-6 days or in high-oxygen barrier (HOB) film for 0-28 days. Aerobic plate counts (APCs) of lean and fat of intact chops packaged and stored in either PVC or HOB film did not differ (P>0·05) in most comparisons. The APCs of subcutaneous fat portions that were packaged and stored separately in HOB film often were higher than those of comparable fat samples of intact chops. There was no consistent pattern of differences in the microflora of lean and fat samples. Differences in mean scores for surface discoloration, off odor and overall appearance of intact chops and chops without subcutaneous fat usually were either not significant (P>0·05) or inconsistent. Lean color scores of chops with or without subcutaneous fat did not differ except that chops with the subcutaneous fat removed were rated higher than intact chops during the early periods of storage. Fat color of subcutaneous fat packaged and stored separately in HOB film was often rated higher (slightly whiter) than that of comparable fat of intact chops.

Differential effects of isoflurane on human median nerve somatosensory evoked potentials.

The effect of isoflurane on median nerve somatosensory evoked potentials (MN-SSEPs) was studied in 15 patients. Anesthesia was induced with thiamylal and maintained with oxygen and isoflurane. MN-SSEPs were recorded in awake patients and after achieving 0.5, 1.0, 1.5, and 2.0% stable end-tidal concentrations of isoflurane. Peak latencies and amplitudes of EP, N13, and N20 and conduction times EP-N13, N13-N20, and EP-N20 were measured. Peak latencies of all components increased after all concentrations of isoflurane compared with control values. N20 peak latencies after 1% and 1.5% isoflurane differed significantly, whereas EP and N13 latencies showed no significant difference. No significant change in conduction time EP-N13 resulted from 1% and 1.5% concentrations of isoflurane compared with control values. Isoflurane increased conduction time N13-N20 significantly when compared with control values, and this increase was dose related. Amplitude of EP and N13 did not show significant change with 1% and 1.5% isoflurane when compared with control values. Amplitude of N20 decreased significantly following isoflurane anesthesia compared with control values, and the difference between 1% and 1.5% isoflurane recordings was also statistically significant. N20 was not discernible in one out of 14 patients after 1.5% and in three out of ten patients after 2% isoflurane. These results indicate that subcortical potentials are less affected by isoflurane anesthesia than cortical potentials. Amplitude reduction of cortical potentials was more noticeable than either prolongation of peak latency or conduction time.(ABSTRACT TRUNCATED AT 250 WORDS)

Spray-chilling and carcass decontamination systems using lactic and acetic acid.

After slaughter, beef carcasses (n = 20) in groups of two were subjected to five treatments (one side only) including intermittent spray-chilling using water, 1% acetic acid or 1% lactic acid, or a single spray treatment with 1% acetic acid or 1% lactic acid. Intermittent spray-chilling consisted of two sprays of 30 s duration per hour for 12h. Single spray treatment consisted of one 30 s spray after entering the chill cooler. The other side of each carcass (control) was air chilled (at 2 to 3°C; air velocity 1 to 3 m/s) only. Five subprimal cuts were taken from each side at 48 h post mortem, vacuum packaged and stored for 28 days at 2°C. Intermittent sprays of sides with acetic or lactic acid resulted in significant (1.8-4.3 log/cm(2)) reductions in aerobic plate count of the strip loin, boneless rib and clod over their controls after these subprimal cuts had been vacuum packaged and stored for 28 days at 2°C in high-oxygen barrier (HOB) film. Lactobacillus spp. were dominant in the microflora of the subprimals from the control and treated sides. When sides were treated with a single sprays of acid, significant reductions in APC were noted only for some cuts of sides treated with lactic acid. After 28 days of storage, there were few significant differences in percentage purge, lean color, and off-odor scores between subprimals from control and treated sides.