Frequency analysis of the electrocardiogram with maximum entropy method for identification of patients with sustained ventricular tachycardia.

Late potentials in the terminal phase of the QRS-complex during sinus rhythm have been proposed to identify a subgroup of patients with myocardial infarction at risk of ventricular tachycardia (VT). Frequency analysis of the ECG with Fourier transform (FFT) has been applied for detection of these microvolt level signals, but is limited by poor frequency resolution of short data segments and spectral leakage. We therefore developed frequency analysis using the maximum entropy method (MEM) based on an autoregressive (AR) model. Orthogonal electrocardiograms were recorded from the body surface of patients with and without VT, and healthy persons after low noise, high-gain amplification. Multiple 40 ms segments (time intervals 2 ms, AR-parameters tapered) were analyzed (spectrotemporal mapping): low-frequency components were eliminated by building difference spectra with optimal high order and fixed low order. The MEM-spectra revealed high frequency components (40-200 Hz) in the terminal phase of the QRS-complex and in the ST-section in 26/38 patients with VT, but only in 2/20 without VT and in 1/20 healthy persons (p less than 0.05). Unlike FFT, MEM allowed localization of late potentials by the analysis of short data segments. Thus, MEM offers promise for noninvasive identification of patients with sustained VT after myocardial infarction and detailed analysis of late potentials.

[Enzootic otitis in a herd of calves]. / Otitis-Enzootie in einem Kälberbestand.

Following an outbreak of enzootic bronchopneumonia, 15 out of 19 calves of one herd were affected by uni- or bilateral otitis media. The animals (aged four days to nine weeks) were housed in individual boxes. Type and distribution of concurrent diseases as well as the symptoms indicative of otitis are listed in two tables; two other tables give the results of the bacteriological examinations of aural and nasal swabs taken before and during treatment. In order to cure otitis media, systemic as well as simultaneous local treatments are necessary. The application of oily suspensions of antibiotics into the auditory canal cannot be recommended. Twelve of the 15 sick calves recovered.

Top-resolution frequency analysis of electrocardiogram with adaptive frequency determination. Identification of late potentials in patients with coronary artery disease.

Frequency analysis of the electrocardiogram with Fourier transform is a sensitive method of detecting late potentials. However, information about localization of late potentials is lost, frequency resolution is poor, and window functions have to be applied. We therefore analyzed multiple segments (25 msec long) of the surface electrocardiogram ("spectrotemporal mapping") with adaptive frequency determination (AFD), an autoregressive algorithm that is characterized by high-frequency resolution in very short segments without the use of window functions. Results were compared with those from Fourier transform and the Simson method. We studied 38 patients after myocardial infarction (MI) with sustained ventricular tachycardia (VT), 21 patients after MI without VT, and 18 healthy subjects. Frequency peaks could be clearly differentiated until a minimal interval of 6 Hz; with fast Fourier transform (Blackman Harris window) in a much longer segment (80 msec), the spectral peaks merged into one another at an interval of about 30 Hz. AFD revealed high-frequency components as narrow peaks in the range of 40-160 Hz in 28 of 38 patients (74%) after MI with VT. Because of the short segment size, exact localization of late potentials was possible; in most of the patients, the peaks occurred in segments inside the QRS complex and ended 20 +/- 10 msec after termination of the QRS complex. In patients after MI without VT, only four of 21 patients (19%) had spectral peaks in segments after the end of the QRS complex; however, 13 of 21 patients demonstrated microvolt potentials in segments within the QRS complex. These potentials did not extend beyond the end of normal ventricular activation. Only two of 18 healthy subjects showed abnormal AFD results. Patients with bundle branch block did not need to be excluded. AFD allowed good differentiation between late potentials and noise by a characteristic pattern of the spectral peaks. For the Simson method, patients with bundle branch block had to be excluded, and overall sensitivity was 42%. In five cases, the cause of failure of the Simson method could be identified as incorrect determination of the QRS limits due to noise. Thus, AFD is a promising method for detailed analysis of late potentials; it combines the advantages of frequency analysis (good differentiation between signal and noise and high-pass filters not necessary) and time domain analysis (localization of late potentials).

The distribution of African swine fever virus isolated from Ornithodoros moubata in Zambia.

African swine fever (ASF) has been reported in the Eastern Province of Zambia since 1912 and is now considered to be enzootic there. A survey of the distribution of ASF virus in Zambia was carried out by virus isolation from Ornithodoros moubata ticks collected from animal burrows in National Parks and Game Management Areas in northern, eastern, central and southern Zambia. ASF virus was isolated from ticks in all areas examined. The prevalence of infection in O. moubata was between 0.4% in South Luangwa National Park and 5.1% in Livingstone Game Park and mean infectious virus titres ranged from 10(3.4) HAD50/tick in Kakumbe Game Management Area to 10(5.9) HAD50/tick in Chunga and Nalusanga Game Management Areas. The prevalence of infection in adult ticks was between 4.7% and 5.3% in all areas examined except Sumbu National Park and Livingstone Game Park, where the prevalence was 15.1% and 13.2% respectively in adult ticks. The ratio of infected females to males for all the infected adult ticks in all areas of Zambia was 3.2:1.

[The hygiene of keeping dogs in city apartments]. / Untersuchungen über die Hygiene bei der Haltung von Hunden in städtischen Wohnungen.

16 family households with school-aged children and 15 elderly couples without children were questioned about their views on the hygienics of holding dogs in their apartment. The dogs of each household were clinically treated three times at intervals of four weeks. Samples were taken of dog feces and smears were made of the oral mucosa, skin, feeding dishes, water bowls and of their resting places for parasitological, bacteriological and mycological examinations. Families with children had a more positive attitude towards keeping a dog in the household than did elderly couples who had no children. At the beginning of the investigation all dogs were clinically healthy; most dogs had been dewormed and had received the usual vaccinations. On checking for ectoparasites, there were only two cases of dogs with fleas. An examination for endoparasites and the mycological examination were negative except for two unrelated and insignificant cases of dogs with Toxocara canis. The bacteriological examination demonstrated that among the majority of healthy dogs the very low concentration of bacteria of test areas remained unchanged. There was no difference between the two groups of households as far as the concentration of bacteria was concerned. In outbreaks of diseases such as occasional diarrhea and dermatitis there was a large concentration of E. coli and Staphylococcus aureus in all test samples. The lack of adequate hygiene leads to an increase of bacteria and to an extreme increase of pathogenic bacteria (staphylococci, Pseudomonas aeruginosa). During the study no one became sick (including children) and there was no food poisoning with staphylococcus although the dogs' feeding dishes and water bowls stood in the kitchen. Salmonellae could not be demonstrated. An assessment of the results of the study confirms that keeping dogs in city households does not pose a danger to the health of humans when hygienic conditions are good.

Treatment of theileriosis with parvaquone in Zambia.

Parvaquone was used to treat 126 cattle with theileriosis. Theileria species schizonts were present in their lymph node biopsy smears and the majority of the animals had clinical signs of theileriosis. One hundred and fifteen treated and one untreated cattle survived the infection while 11 treated and 12 untreated animals died of the disease. Despite serological evidence of a parasite challenge during the subsequent rainy season, recovered cattle did not develop clinical signs of theileriosis but untreated cattle in the area continued to die from the disease. An intermittent low piroplasm parasitaemia (less than 1 per cent) was observed in recovered cattle for up to 14 months after detailed monitoring of cattle in the trial; this could be evidence for a carrier status for the Theileria species or strains involved.

Evaluation of the anaesthetic properties of ketamine and a ketamine/xylazine/atropine combination in sheep.

The anaesthetic properties of ketamine in sheep were evaluated and compared with the results of a combination of ketamine/xylazine and ketamine/xylazine/atropine. Premedication of xylazine/atropine followed by intravenous injection of ketamine hydrochloride appeared to result in satisfactory immobilisation and anaesthesia for surgical operations of short duration. This combination effectively reduced some of the undesirable effects of ketamine, such as muscle rigidity, insufficient suppression of reflexes and tachycardia. The action on haematological factors was studied and significant increases in blood glucose content were detected during anaesthesia.

The effect of Gn-RH on the pregnancy rate of artificially inseminated cows.

One hundred and nine pure bred Holstein Friesians were injected intramuscularly with 0.125 mg of a synthetic Gn-RH analogue at the time of the first service to study the effect of Gn-RH on the fertility of inseminated cows. Sixty-four cows or 58.7 per cent were diagnosed as pregnant after one insemination compared to 54 animals or 49.5 per cent in the untreated control group. Total pregnancy rate of 81.65 per cent was 8.3 per cent higher than in the controls, while the services per conception rate improved from 1.49 to 1.39. Gn-RH administration at the time of oestrus could improve herd fertility through its including effect on follicular rupture and regulatory influence on ovarian function.

The use of heat mount detectors in a large Iranian dairy herd.

Heat mount detectors were applied in a large Iranian dairy herd in an attempt to appraise their value for fertility improvement. A total of 100 cows with a recorded anoestrous period of at least 60 days were selected, 69 of them suffering from suboestrus or silent heat and 31 from true anoestrus due to inactive ovaries. The results indicate that inaccurate observation of heat is a major limiting factor in the reproductive performance of this herd and that heat detectors could be a valuable tool for improvement of oestrus detection and consequent reduction of the interval from calving to conception.

Lamellar corneal transplantation in the horse.

Surgical correction of corneal opacities in horses has rarely been documented in detail and is still reported to be in the experimental stage. For this reason, studies of lamellar keratoplasty were conducted on the equine eye using a modified trephine with an adjustable inside quard for grafting of identical discs from the donor and the recipient cornea. Fourteen transplantations, seven with homografts and seven with heterografts, 15 and 9 mm in diameter, were performed. Sharp-edged, vertical, and regular outlined wound margins of the graft and host are essential for good adaptation and healing without tension. The details of instruments used, preoperative preparation, surgical technique, and postoperative care are described. Results indicated that this method is a feasible tool for the repair of corneal defects in the horse and may be usefully employed in an intention to restore vision.