Inhalation anesthetics.

The inhalation anesthetics affect operating room personnel as well as the patient. This occupational exposure is similar in all respects to industrial solvent exposures. Although the extent of the hazard is not yet established, it is clear that only quite low levels of these active chemical should be allowed in the operating room air.     

Inhalation Therapy

Joint Accord on the Role of Respiratory (Inhalation) Therapy Personnel in Airway Management and Endotracheal Intubation endorsed by the California Medical Association, the California Hospital Association, the California Society for Respiratory Therapy, the California Society of Anesthesiologists and the California Thoracic Society.     

Microevolution in island rodents

We perform a meta-analysis on morphological data from four island rodent populations exhibiting microevolution (>100 years). Data consisting of incidences of skeletal variants, cranial, and external measurements are from house mice (Mus musculus) on one Welsh and one Scottish island, black rats (Rattus rattus) on two Galapagos islands, and deer mice (Peromyscus maniculatus) on three California Channel islands. We report extremely high rates of microevolution for many traits; 60% of all mensural traits measured changed at a rate of 600 d or greater (max. 2682 d). The proportion of all mensural traits evolving at 600–800 d (23%) was idiosyncratic and departed from an expected negative exponential distribution. We argue that selection, rather than founder events, is largely responsible for the substantial shifts in morphology seen among insular rodents. Examining individual traits, there is a trend towards the nose becoming longer and wider, while the skull becomes shallower, shown by both rats and mice on five different islands. We found a significant correlation between island size and degree of skeletal variant evolution and between island distance from the mainland (or nearest island) and degree of cranial and external character evolution. Thus, microevolution of rodents is greater on smaller and more remote islands.     

Inhalation anesthesia in adult cattle

An inhalation technique was used for anesthesia during ileal cannulation in five adult cows. Following sedation with intravenous acepromazine, anesthesia was induced intravenously with thiopental sodium in 5% glyceryl guaiacolate solution. Endotracheal intubation was performed and anesthesia maintained with halothane in oxygen via a circle system with a precision vaporizer. In all cases, induction was smooth and no difficulties were experienced during the maintenance of anesthesia. Total anesthesia time was 1.5 to 2.5 hours. Following completion of the surgical procedure, which was performed with the animal in left lateral recumbency, each cow was rolled to a sternal position and supported, if necessary. The endotracheal tube was left in place, with oxygen administration continued, until the animal was able to swallow. Recoveries were rapid and all animals were ambulatory within 30 minutes after completion of the surgery. The only post-operative complication due to anesthesia was transient mouth soreness in two cases, attributed to the use of a mouth speculum during intubation.     

Geomagnetic field detection in rodents

In addition to behavioral evidence for the detection of "earth-strength" magnetic fields (MF) by rodents, recent investigations have revealed that electrophysiological and biochemical responses to MF occur in the pineal organ and retina of rodents. In addition, ferrimagnetic deposits have been identified in the ethmoidal regions of the rodent skull. These findings point to a new sensory phenomenon, which interfaces with many fields of biology, including neuroscience, psychophysics, behavioral ecology, chronobiology and sensory physiology.     

Chromosome evolution in Australian rodents

The chromosome complements of 188 specimens of 29 species of Australian murid rodents belonging to the subfamilies Pseudomyinae and Hydromyinae and the Uromys/Melomys group have been compared. At least one specimen of 18 different species was successfully C-banded. — The autosomal complements of many (9) diverse Pseudomyinae, one species of Melomys and one Hydromyinae proved to be identical, comprising 48 elements in the diploid set, the two smallest autosomal pairs of which are metacentric. No other karyotype is common to more than one species. From this we conclude that these three groups have been derived from a common ancestor which also possessed such a karyotype. The genus Zyzomys is exceptional since it possesses only 44 elements and lacks the two smallest metacentrics. — Karyotypic evolution within this apparently single phyletic line has been remarkably conservative, only three rearrangements being required to derive the most divergent karyotype. Moreover most of the observed rearrangements involve pericentric inversions and only one example of a fusion was found. Considerable differences in heterochromatin content, as determined by C-banding, occur between species however. Two species proved exceptional in this respect, namely Notomys cervinus and Uromys caudimaculatus. N. cervinus possesses numerous heterochromatic short arms. In U. caudimaculatus, there is a striking difference between northern and southern populations; in the former heterochromatin is present principally in the telomeric areas of the conventional A-chromosomes whereas in the latter it is found as separate supernumerary chromosomes. — In contrast to the autosomes, the X and Y chromosomes show high inter- and intra-specific variability in both size and morphology. All of this variability can be explained in terms of variation in heterochromatin content. Moreover the amount of heterochromatin in the X and Y chromosomes is highly correlated both within and between species. The Y chromosome of Uromys caudimaculatus is, however, distinctive in that it lacks C-banding.     

Chromosome evolution in Australian rodents

A total of 219 wild caught specimens representing 12 of the currently recognised 13 species and subspecies of Australian Rattus have been karyotyped. No two species possessed karyotypes in common, most species and several subspecies differing markedly in chromosome number. While the diploid number varied from 2n=32 to 2n=50, the fundamental number (FN) varied only from 60 to 62, suggesting that Robertsonian rearrangements have played a major role in karyotypic evolution in the group. — Karyotypically the Australian species of Rattus fall into two groups. — the R. lutreolus group and the R. sordidus group. Of the karyotypic forms encountered in the former group, that of R. lutreolus is probably most ancestral because it is identical to that of many Asian species of Rattus. Other karyotypic forms in the R. lutreolus group can be derived as follows: That of (1) R. tunneyi tunneyi and R. t. culmorum by a single fixed pericentric inversion; (2) R. fuscipes fuscipes, R. f. greyi, R. f. assimilis and R. f. coracius by two fixed fusions; (3) R. leucopus cooktownensis by three fixed fusions; and (4) R. leucopus leucopus by four fixed fusions. Of the R. sordidus group, R. s. villosissimus may possess the most ancestral karyotype with 2n=50 (FN=60), from which R. s. colletti (2n=42; FN=60) is derived by four fusions and R. s. sordidus (2n=32; FN=60) by nine fusions, four of which appear to be homologous with those R. s. colletti. — The karyotypic data are in accord with Taylor and Horner's (1973) suggestions that (1) R. t. tunneyi and R. t. culmorum belong to one species; (2) R. lut. lutreolus and R. lut. velutinus belong to one species; (3) R. leu. leucopus and R. leu. cooktownensis belong to one species and (4) R. f. fuscipes, R. f. greyi, R. f. assimilis and R. f. coracius belong to one species. However, the large karyotypic difference between R. s. sordidus and R. s. colletti and R. s. villosissimus may indicate that these groups belong to different biological species. — Supernumerary or B-chromosomes were found in R. f. assimilis and R. t. tunneyi. A single R. t. culmorum was heterozygous for a centric fusion.     

Hemoglobin affinity in Andean rodents

Blood hemoglobin oxygen affinity (P50) was measured in three Andean species and in the laboratory rat (control), all raised near sea level. Chinchilla lanigera (Molina, 1792) has an altitudinal habitat range from low Andean slopes up to 3000 m., while Chinchilla brevicaudata (Waterhouse, 1848) has an altitudinal range from 3000 to 5000 m. The laboratory type guinea pig, wild type guinea pig (Cavia porcellus), (Waterhouse, 1748), and laboratory rat (Rattus norvegicus) were also raised at sea level. The Andean species had high hemoglobin oxygen affinities (low P50) compared with the rat. Chinchilla brevicaudata had a higher affinity than Chinchilla lanigera. The wild type guinea pig had a higher affinity than the laboratory type. As has been shown in other species, this is another example of an inverse correlation between the altitude level and the P50 values. This is the first hemoglobin oxygen affinity study in Chinchilla brevicaudata.