Age determination and validation studies of marine fishes: do deep-dwellers live longer?

Age determination and validation studies on deep-water marine fishes indicate they are difficult to age and often long-lived. Techniques for the determination of age in individual fish includes growth-zone analysis of vertebral centra, fin rays and spines, other skeletal structures, and otoliths (there are three sets of otoliths in most bony fish semicircular canals, each of which is made of calcium carbonate). Most have regular increments deposited as the fish (and its semicircular canals) grows. The most commonly used otolith for age determination is the largest one called the sagitta. Age validation techniques include: (1) tag-recapture, often combined with oxytetracycline injection and analysis in growth-zones of bone upon recapture; (2) analysis of growth-zones over time; and (3) radiometric approaches utilizing a known radioactive decay series as an independent chronometer in otoliths from bony fishes. We briefly summarize previous studies using these three validation approaches and present results from several of our radiometric studies on deep-water, bony fishes recently subjected to expanding fisheries. Radiometric age validation results are presented for four species of scorpaenid fishes (the bank, Sebastes rufus, and bocaccio, S. paucispinis, rockfishes, and two thornyhead species, Sebastolobus altivelis and S. alascanus). In addition, our analysis of scorpaenids indicates that longevity increases exponentially with maximum depth of occurrence. The reason that the deep-water forms of scorpaenid fishes are long-lived is uncertain. Their longevity, however, may be related to altered physiological processes relative to environmental parameters like low temperature, high pressures, low light levels, low oxygen, and poor food resources.

Conventional versus laser reanastomosis of rabbit ligated uterine horns.

Conventional microsurgical reanastomosis was compared with laser microsurgical reanastomosis of the ligated uterine horn in the rabbit. Fourteen virgin female New Zealand white rabbits had both uterine horns ligated and divided at laparotomy. Four weeks later, seven rabbits had conventional microsurgical reanastomosis of the divided uterine horns after the ligated stumps were excised (group 1). The ligated uterine horns of the other seven animals were incised with a carbon dioxide laser with a power density of 637 to 796 W/cm2 followed by conventional microsurgical reanastomosis using polyglactin (Vicryl) 8-0 sutures (group 2). After six weeks, a laparotomy was performed to determine adhesion formation and uterine horn patency by chromopertubation. Adhesion formation was graded 0 (no adhesions) through 3 (extensive, dense adhesions) for each uterine horn. Only one uterine horn in the control group was not patent. Laser microsurgery produced significantly less adhesion (mean +/- SE, 0.79 +/- 0.24) than conventional microsurgery (2.29 +/- 0.13) (P less than .001). The findings indicate that laser microsurgical tubal reanastomosis produces significantly better results with less adhesion than the conventional microsurgical technique.

Clinical and histologic evaluation of laser reanastomosis of the uterine tube.

Conventional microsurgical reanastomosis was compared with laser microsurgical reanastomosis of previously ligated uterine tubes in 14 rabbits. A final laparotomy was performed to determine adhesion formation and uterine tube patency, and a histologic examination was done of the anastomosis sites using four histologic indices for grading. Laser microsurgery produced significantly less adhesions (mean +/- standard error of the mean adhesion score, 0.79 +/- 0.24) than conventional microsurgery (2.29 +/- 0.13, P less than 0.001). However, there was no significant difference in all four histologic indices of tissue reunion at the anastomosis site between the two types of surgical technique. In a separate experiment, CO2 laser was found to be unable to weld uterine tubes successfully. Thus, the CO2 laser can significantly reduce postoperative adhesions in microsurgical uterine tube reanastomosis but without any significant histologic difference in tissue reunion, compared with conventional microsurgery.

Nonisothermal kinetics using a microcomputer: a derivative approach to the prediction of the stability of penicillin formulations.

A procedure is described for the determination of the shelf-life of pharmaceutical preparations using nonisothermal kinetics. A BASIC computer program, which enables the data analysis to be undertaken rapidly and automatically on a microcomputer, is presented.

Anesthetic management for carbon dioxide laser surgery of the larynx.

Fifty-one patients underwent 71 carbon dioxide laser procedures under general anesthesia for various intralaryngeal pathology. Anesthesia was induced with thiopental sodium, followed by succinylcholine to facilitate endotracheal intubation. For maintenance of anesthesia, 70% nitrous oxide was supplemented with halothane, enflurane or small doses of fentanyl. Succinylcholine, d-tubocurare or pancuronium were used to maintain muscular relaxation of jaw, pharyngeal and laryngeal muscles for a smooth lasing procedure. Small diameter (16-22 Fr.), red rubber, cuffed endotracheal tubes provided maximum working space, facilitated the controlled ventilation and reduced the explosion hazard of the anesthetic gases. Safely eyeglasses were used by all the personnel in the operating room against accidental injury to the cornea by the laser beam. Anesthetic management provided excellent operative conditions with maximum safety to the patient and the personnel in the operating room.

Laser adapter for tracheoscopy.

This adapter makes it possible for the operating microscope to be used monocularly, to see axially down the CO2 laser beam, to use the aiming light and its joy stick control. This makes the laser useful for upper tracheal lesions through a tracheoscope.

Carbon dioxide laser treatment of metastatic melanoma of the trachea and bronchi.

An occasional patient with metastatic or recurrent malignant disease develops intraluminal masses in the trachea and/or the main bronchi. The accuracy of the application, absence of bleeding, slight reaction, and rapid healing make the CO2 laser applied through the open bronchoscope a valuable palliative treatment for the relief of obstructive dyspnea. This patient is reported because he demonstrated the reduced bleeding which occurred with the bronchoscopic CO2 lasing as compared to bronchoscopic forceps removal.

General techniques and clinical considerations in laryngologic laser surgery.

The carbon dioxide laser, one of the great advances in otolaryngology, has the characteristics of accuracy, reduced bleeding, reduced reaction, faster healing, and less scarring as compared with conventional surgery. Its beam is produced by creating an electric discharge within a cylinder containing carbon dioxide, nitrogen, and helium. The emitted beam is invisible, and special means are used to show exactly where the beam is going to impinge on the tissue. The effect of the power delivered to the tissue by the laser beam depends on the character of the tissues, the presence of char, the delivery device, and the condition of the lenses and mirrors. The imprint size varies with the power and the duration of exposure and is not necessarily the same as spot size. Repeated exposures increase the amount of tissue destruction and can be used to completely eradicate a lesion until the junction of normal and abnormal tissue is encountered. The following points and techniques are important in determining the results of carbon dioxide laser surgery. Increasing the power and reducing the duration of the beam result in less charring, less reaction, and faster healing. Overheating of tissues is avoided by using a skip technique. Char must be removed to prevent overheating of tissues and to aid in identifying accurately the junction of normal and pathologic tissues. Palpation may help identify pathologic tissue not readily apparent on inspection alone. The edge of the beam can be used to shave away pathologic tissue accurately while preserving normal tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of maxillary tooth development to estimate age in a group of Hereford cross Friesian steers.

Visual and radiographic examination of maxillary tooth development was undertaken in a group of 76 Hereford cross Friesian steers, all but one slaughtered at the same weight (464 kg). Differences were found in the stages of second molar intraoral development between the various age groups. Radiographic inspection showed that stages of resorption of the temporary premolar roots and crown and root formation of the permanent cheek teeth varied with age. The maximum age range before animals could be differentiated into age groups using radiographic examination of maxillary tooth development was three months (one year from one year three months, one year three months from one year six months, one year four months from one year seven months, one year five months from one year eight months). In the carcase, radiography of the maxillary teeth provided a useful estimate of age. The first two maxillary molars were more advanced in crown and root formation than the permanent premolars. Except for the second permanent premolar all maxillary teeth were less advanced in development than their mandibular counterparts.

The relationship of maxillary cheek tooth development to age in young Friesian cattle.

Radiographs were taken of both the right and left sets of maxillary teeth in 23 Friesian cattle of known age. The stage of development of each permanent tooth was ascertained and the degree of root resorption in the deciduous premolars was noted. All stages in individuals were later than for those of the mandibular cheek teeth except in the case of the first permanent premolar. As with mandibular cheek tooth development stages of formation occurred within certain age limits.

Mandibular cheek tooth development and its relationship to age in young Friesian cattle.

The oral and intra-osseous development of each of the six manidibular cheek teeth found in the permanent dentition of cattle was studied. The animals used were all British Friesians, of varying sex, and slaughtered at different weights at ages between 13 and 22 months. The various stages of development observed in each tooth together with the mean age and age range at which they were seen are recorded. Significant differences were found between the ages at which several of the developmental stages were seen in most of the teeth and indicated that tooth formation in the Friesian cattle studied tended to fall within well defined age limits.

Use of second molar eruption in age estimation of cattle.

The intra-oral development of the second molar in cattle was examined using a system of molar codes based on degree of eruption. Observations on eight Friesian heifers seen more than once were compared with those from 320 cattle studied by the cross-sectional method. The average ages of the Friesians for a given degree of eruption tended to be higher than those in the larger survey. There were too few data to provide a statistical comparison but, by using the age range for each stage of second upper molar development, it was found that in absolute terms an animal showing no emergence of the tooth was younger than one exhibiting complete eruption of the rostral and caudal units. In addition, in most cases an animal at molar code 1 (rostral unit emerging, caudal unit not visible) was younger than one at molar code 8 (rostral and caudal units both fully up). Although the method of second molar development had limitations in age estimation it did provide an indication at a time before eruption of the first permanent incisor tooth pair and the age range at each stage of molar development tended to be lower than for the permanent rostral teeth.

A radiographic study of rostral tooth development in young Friesian cattle.

Twenty-nine British Friesian cattle fed the same diet, slaughtered at various weights and including bulls, steers (castrated males) and females (heifers) were examined. The stage of their rostral tooth development was recorded both visually and radiographically. Insufficient animals were present in each sex and slaughter weight treatment group to allow any comparison between them. When the data for each sex were compared, no statistically significant differences were seen between the mean ages at which bulls, steers and heifers attained each stage of dental development as determined from their radiographs. The results for all 29 cattle were then combined. This combined data showed a relationship between age and those stages of tooth formation which could be differentiated by examination of the X-ray films. As most phases of tooth formation occurred within well defined limits, it is suggested that radiographs of rostral tooth development might be used to estimate the age of cattle.

Mandibular cheek tooth eruption and development in Hereford cross Friesian steers as a means of age determination.

The development of the mandibular cheek teeth was examined, both visually and by radiograph, in a group of 76 Hereford cross Friesian steers, of which all but one were slaughtered at the same weight - 464 kg (1020lb). The age of the youngest animal was 1 year 0.3 months whereas the slaughter ages of the others ranged from 1 year 3 months to 1 year 8 months. The first molar was fully erupted and crown and root formation complete in all but the youngest steer. In the other five cheek teeth there were one or more significant differences between the mean ages of tooth development stages as assessed by radiograph. Cattle of 1 year 3 months could not be absolutely distinguished from those of 1 year 8 months by intra-oral second molar eruption. Examination of stages of development seen radiographically gave a maximum age range of 4 months before differentiation. In this study, development of the first two molars was in advance of the three permanent premolars and in these latter teeth the second premolar was the most developed.

First molar eruption in cattle and its use in age determination.

Two studies were undertaken into the intraoral eruption of the first molar in live cattle. The first was a longitudinal survey using monthly observations of Welsh Black bulls and the second involved 300 animals of both sexes and varying breeds, reared under different management systems, using the cross-sectional technique. There were significant differences between the ages at most successive molar codes in both studies. However, a comparison between the two studies showed the mean age at each stage of molar development was higher in the longitudinal study and at three stages this was significant. The age range for each molar code, obtained from the two studies combined, varied between 2.0 and 4.7 months but indicated that the eruption of the first molar tooth was of use in age assessment.

Age detection by radiography in Hereford cross Friesian steers.

The mandibles of 78 Hereford cross Friesian steers all showing a full complement of temporary teeth were examined both visually and by radiography to determine whether it was possible to differentiate their various ages. All but one animal were slaughtered at the same weight (1020 lb-464 kg) and their ages at slaughter ranged from 1 year 3 months to 1 year 9 months. Differences were found between the mean ages for stages of resorption of the first temporary incisor roots, stages of first permanent incisor root formation and stages of second incisor crown formation, as determined by radiographic inspection. The results indicated that the age of a group of animals could be defined, but the age range within each development stage meant that it was not possible to define the age of individual cattle.

Clinical signs and treatment of aged sheep with loose mandibular or maxillary cheek teeth.

Five cases of loose mandibular or maxillary cheek teeth in sheep are described. All the sheep showed loss of condition but excessive salivation was not a consistent feature. Two had high helminth egg counts, one a facial abscess and three loose rostral teeth. Blood biochemical results showed raised creatine phosphokinase (three cases), low glucose (three) and marginally low calcium levels (two). Diagnosis was based on digital palpation of the teeth during sedation. Treatment by extraction of loose teeth allowed a further litter of lambs from pregnant ewes and an extra tupping season from a ram.

Abnormal reactions and their frequency in cattle following the use of organophosphorus warble fly dressings.

The signs and treatment of abnormal reactions following the use of organophosphorus systemic warble fly dressings are recorded. A review is provided of all complaints received by the manufacturers and distributors of such compounds during the dressing periods for the years 1975 to 1978. The volume of warble fly dressing sold each year was known and the number of cattle dressed was based on the calculation of the number of adults which could have been treated with the volume. Complaints were divided according to the main signs reported and the most common complaint was that of paralysis-incoordination. The incidence of death or slaughter following use of an organophosphorus compound was one in 93,000 animals treated. The majority of animals showing abnormal signs other than paralysis-incoordination were involved in incidences of skin lesions, depressed milk yield, bloat or 'other reactions'. Compared with the number of animals treated, the level of reported reaction was low (one complaint per 46,000 animals treated).

Factors affecting the incidence of pneumonia in growing bulls.

The occurrence of respiratory disease at two Meat and Livestock Commission bull performance test centres over a period of three years is assessed. During this period a change in the system of testing was introduced so as to allow younger bulls to enter the centre and also to increase their throughput. This resulted in an increase in the incidence of pneumonia of more than five times. The management at one centre was changed to counteract this disease problem and the level of pneumonia was greatly reduced. Most respiratory disease occurred within the first month of entry to the centres. There was more infection during the second half of the year and especially in the October to December quarter. There appeared to be some relationship between the time bulls were weaned prior to entry to the centres and the incidence of pneumonia.

Long-acting antibiotic formulations in the treatment of calf pneumonia: a comparative study of tilmicosin and oxytetracycline.

The treatment of an outbreak of acute pneumonia in 50 four- to eight-month-old Friesian and Friesian cross calves is described. At the first visit (day 0) 16 calves received 20 mg/kg bodyweight of oxytetracycline dihydrate intramuscularly and 15 received 10 mg/kg of the macrolide tilmicosin subcutaneously. The remaining 19 in-contact animals were not considered ill enough to be included in the trial and received 20 mg/kg of oxytetracycline dihydrate. The rectal temperature, demeanour, respiratory rate and respiratory effort of each calf was assessed on days 1, 2, 3, 9, 14, 21 and 28, and calves which had not responded were given repeat injections of the same antibiotic. All the calves recovered from the outbreak and of the 19 calves treated strategically, three required a second injection. Among the calves with clinical pneumonia, fewer treatments (P less than 0.01) were required by those treated with tilmicosin. The rectal temperatures of both groups decreased (P less than 0.05) after the first injection, but on day 3 the decrease was greater (P less than 0.05) in the group treated with tilmicosin. Respiratory rates varied widely but respiratory effort was less (P less than 0.05) on day 2 in the calves treated with tilmicosin. When long-acting antibiotic injections are used to treat enzootic pneumonia it is suggested that a second visit should be made on day 3 to assess the animals' response to treatment.