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The thalamus of reptiles and mammals: similarities and differences.

Certain aspects of thalamic organization in reptiles and mammals are reviewed. Features shared by the dorsal thalamus of reptiles and that of mammals include projection to the telencephalon, specific and non-specific non-telencephalic afferents, and input from the thalamic reticular nucleus. Differences between the dorsal thalamus of reptiles and that of mammals are the absence of reciprocal telencephalic efferents to the dorsal thalamus and lack of local circuit neurons in reptiles (with the exception of the dorsal geniculate complex in turtles) and their presence in mammals. A thalamic reticular nucleus is present in both reptiles and mammals. In both of these classes of vertebrates, this neuronal aggregate surrounds the dorsal thalamus along its lateral surface, projects to the dorsal thalamus, and is organized into sectors. In one group of reptiles, Caiman crocodilus, the sole reptilian group in which immunocytochemical features have been investigated in detail, the reticular nucleus contains at least three neuronal subpopulations: neurons immunoreactive for glutamic acid decarboxylase (GAD); neurons immunoreactive for parvalbumin; and cells that are not immunoreactive for parvalbumin or, probably, GAD. On the other hand, the reticular nucleus of mammals contains a single population of neurons immunoreactive for GAD, gamma amino butyric acid, and parvalbumin.

Animals↗

Evaluation of the use of anesthesia and analgesia in reptiles.

OBJECTIVE: To determine anesthetic techniques and the drugs used to provide anesthesia and analgesia to reptiles. DESIGN: Mail-out questionnaire. SAMPLE POPULATION: 367 members of the Association of Reptile and Amphibian Veterinarians. PROCEDURE: 1,091 members listed in the 2002 directory of the Association of Reptile and Amphibian Veterinarians were asked to complete a questionnaire regarding anesthesia and analgesia. RESULTS: 367 of 1,091 (33.6%) individuals completed the questionnaire; 88.8% used inhalants (particularly isoflurane) for anesthesia, and ketamine, propofol, and butorphanol were the most commonly used injectable agents. Intubation, fluids, and having a dedicated anesthetist were most commonly used for patient support, and pulse oximetry and Doppler ultrasonography were most commonly used for monitoring. Respiratory depression, difficulty monitoring anesthetic depth, prolonged recovery, and hypothermia were the most frequent complications. Nearly all respondents believed that reptiles feel pain, but analgesics were used infrequently for many reasons. CONCLUSIONS AND CLINICAL RELEVANCE: Providing anesthesia in reptiles is difficult, especially regarding anesthetic depth and vital parameters, and methods of support are used less frequently than in domestic species. Provision of analgesia is uncommon. Research regarding pain and its assessment, response to analgesics, and drug pharmacokinetics is needed. Dissemination of this information to practitioners needs to be improved for enhancement of the standard of care for reptiles.

Analgesia↗

Reptile-associated salmonellosis--selected states, 1998-2002.

During 1998-2002, CDC received reports from state health departments regarding Salmonella infections in persons who had contact with reptiles (e.g., lizards, snakes, and turtles). Salmonella infections usually cause gastroenteritis but can result in invasive illness (e.g., septicemia and meningitis), especially in infants and immunocompromised persons. For decades, reptiles have been known as a source for salmonellosis; however, numerous reptile owners remain unaware that reptile contact places them and other household members, including children, at greater risk for salmonellosis. Increasing evidence suggests that amphibians (e.g., frogs, toads, newts, and salamanders) also can pose risks for salmonellosis in humans. This report describes cases of reptile-associated salmonellosis in six states, offers recommendations on preventing transmission of Salmonella from reptiles and amphibians to humans, and provides an update on state regulations mandating education at pet stores about salmonellosis.

Adolescent↗

[O-serovar distribution and antibiotic sensitivity of Pseudomonas aeruginosa strains from birds and reptiles].

100 strains of Pseudomonas aeruginosa (P.a.) from birds and reptiles were compared by determination of their O-serovars and their resistance to chemotherapeutic agents. A great number of isolates (birds 17.4%, reptiles 29.6%) were serologically untypable using 17 O-antisera by slide-agglutination-technique. The prevalence of O-serovar 0:6 was found in birds (39%) and reptiles (18.5%), followed by bird-isolates 0:1 and 0:3 (each 13%) and reptile-isolates 0:16 (14.8%). The serological distribution was different among bird- and reptile-isolates and also among the human and animal strains. All strains were resistant to penicillin G and ampicillin, more than 90% to nitrofurantoin, sulfamethoxazole-trimethoprim, chloramphenicol and erythromycin. Resistance to tetracycline was found to be 87%, resistance to sulfonamide 81%, respectively. 32% of all isolates were resistant to streptomycin, 61% to kanamycin. All isolates were susceptible to genta- and neomycin. Also all isolates, except one reptile-strain, were susceptible to gyrase-blocker (Bay VP 2674). 2 isolates were resistant to polymyxin B.

Animals↗

Comparison of the "mammal machine" and the "reptile machine": energy use and thyroid activity.

Oxygen consumption of tissue slices of liver, kidney, and brain were measured at 37 degrees C to assess in vitro metabolism of tissues of Amphibolurus nuchalis and Mus musculus (a reptile and mammal with same weight and body temperature). "Sodium transport" metabolism was also assessed (with use of ouabain) in these tissues. The mammal had an in vitro tissue metabolism that was two to five times that of the reptile and its sodium transport metabolism was four- to ninefold greater. Growth of reptile young and mammal young at the same body temperature was measured and the mammal showed a growth rate that was an order of magnitude greater than the reptile. Thyroid activity was assessed in the reptile and mammal by measurement of thyroidal uptake and release of 125I and serum thyroxine concentration. All parameters indicated a greater thyroid activity in the mammal. These findings are discussed in relation to the action of the thyroid hormones, the paleoecology of mammals and reptiles and the evolution of endothermy.

Aging↗

A comparative study of the metabolic capacity of hearts from reptiles and mammals.

The metabolic capacities of reptilian and mammalian hearts have been investigated using two methods: measurement of mitochondrial enzyme activity (cytochrome oxidase) and measurement of both mitochondrial volume density and membrane surface area. The heart tissues from the reptiles and mammals showed 2-fold "weight specific" and 3-fold total organ metabolic capacity differences. Heart mitochondria from reptiles and mammals showed 2-fold differences in the activity of their enzymes per mg of mitochondrial protein yet showed very similar mitochondrial surface areas per cm3 of mitochondria. Heart mitochondria differ from liver mitochondria which have the same enzyme activities per mg of protein and the same mitochondrial surface area per cm3 of mitochondria in both the reptiles and mammals. A wide variety of reptiles and mammals both showed relationships between total heart metabolic capacity and body weight. Mammals have larger hearts than similar sized reptiles and their hearts have a greater proportion of cellular volume occupied by mitochondria.

Animals↗

Common procedures with venomous reptiles.

Venomous reptiles should be handled in a safe and consistent man-ner, even after death. Owners and staff should be warned not to handle the venomous reptile, and one should have emergency protocols in place before the properly bagged and encased reptile is presented. It is important to know what one is treating as well as one's limitations. After being carefully removed from the bag, the venomous reptile may be transferred to a handling container, tubed, or squeezed with the appropriate equipment. The author usually induces injectable or gas anesthesia at this point. Veterinarians who are inexperienced with venomous reptiles should learn how to handle them through a reputable seminar or class before electing to see them in their practice.

Animals↗

The behavioral responses of amphibians and reptiles to microgravity on parabolic flights.

In the present study, we exposed 53 animals from 23 different species of amphibians and reptiles to microgravity (mug). This nearly doubles the number of amphibians and reptiles observed so far in mug. The animals were flown on a parabolic flight, which provided 20-25s of mug, to better characterize behavioral reactions to abrupt exposure to mug. Highly fossorial limbless caecilians and amphisbaenians showed relatively limited movement in mug. Limbed quadrupedal reptiles that were non-arboreal in the genera Leiocephalus, Anolis, and Scincella showed the typical righting response and enormous amounts of body motion and tail rotation, which we interpreted as both righting responses and futile actions to grasp the substrate. Both arboreal and non-arboreal geckos in the genera Uroplatus, Palmatogecko, Stenodactylus, Tarentola, and Eublepharis instead showed a skydiving posture previously reported for highly arboreal anurans. Some snakes, in the genera Thamnophis and Elaphe, which typically thrashed and rolled in mug, managed to knot their own bodies with their tails and immediately became quiescent. This suggests that these reptiles gave stable physical contact, which would indicate that they were not falling, primacy over vestibular input that indicated that they were in freefall. The fact that they became quiet upon self-embrace further suggests a failure to distinguish self from non-self. The patterns of behavior seen in amphibians and reptiles in mug can be explained in light of their normal ecology and taxonomic relations.

Amphibians↗

Fungal diseases of reptiles.

Fungal infections affecting the integumentary system, the upper and lower respiratory system and the gastro-intestinal tract have been reported in many species of captive reptiles. Systemic mycoses are diagnosed rarely in reptiles, and in most cases, they are a postmortem finding. Commonly, immunocompromised reptiles, kept in suboptimal environmental conditions are affected. In many cases, mixed bacterial and fungal infections of opportunistic organisms may be present. A diagnosis of a primary fungal infection is based on proper selection and collection of diagnostic specimens such as biopsies of infected tissues. Treatment of fungal infections in reptiles includes administration of effective antifungal agents and correction of inappropriate environmental conditions such as poor hygiene, too high or too low temperature and humidity, inadequate diet, and stress from overcrowding. Few studies have investigated effective dosages and dosage intervals of antifungal agents in reptiles.

Animals↗

Reptiles, amphibians, and human Salmonella infection: a population-based, case-control study.

To estimate the burden of reptile- and amphibian-associated Salmonella infections, we conducted 2 case-control studies of human salmonellosis occurring during 1996-1997. The studies took place at 5 Foodborne Diseases Active Surveillance Network (FoodNet) surveillance areas: all of Minnesota and Oregon and selected counties in California, Connecticut, and Georgia. The first study included 463 patients with serogroup B or D Salmonella infection and 7618 population-based controls. The second study involved 38 patients with non-serogroup B or D Salmonella infection and 1429 controls from California only. Patients and controls were interviewed about contact with reptiles and amphibians. Reptile and amphibian contact was associated both with infection with serogroup B or D Salmonella (multivariable odds ratio [OR], 1.6; 95% confidence interval [CI], 1.1-2.2; P<.009) and with infection with non-serogroup B or D Salmonella (OR, 4.2; CI, 1.8-9.7; P<.001). The population attributable fraction for reptile or amphibian contact was 6% for all sporadic Salmonella infections and 11% among persons <21 years old. These data suggest that reptile and amphibian exposure is associated with approximately 74,000 Salmonella infections annually in the United States.

Amphibians↗

Environmental sex determination in reptiles: ecology, evolution, and experimental design.

Sex-determining mechanisms in reptiles can be divided into two convenient classifications: genotypic (GSD) and environmental (ESD). While a number of types of GSD have been identified in a wide variety of reptilian taxa, the expression of ESD in the form of temperature-dependent sex determination (TSD) in three of the five major reptilian lineages has drawn considerable attention to this area of research. Increasing interest in sex-determining mechanisms in reptiles has resulted in many data, but much of this information is scattered throughout the literature and consequently difficult to interpret. It is known, however, that distinct sex chromosomes are absent in the tuatara and crocodilians, rare in amphisbaenians (worm lizards) and turtles, and common in lizards and snakes (but less than 20% of all species of living reptiles have been karyotyped). With less than 2 percent of all reptilian species examined, TSD apparently is absent in the tuatara, amphisbaenians and snakes; rare in lizards, frequent in turtles, and ubiquitous in crocodilians. Despite considerable inter- and intraspecific variation in the threshold temperature (temperature producing a 1:1 sex ratio) of gonadal sex determination, this variation cannot confidently be assigned a genetic basis owing to uncontrolled environmental factors or to differences in experimental protocol among studies. Laboratory studies have identified the critical period of development during which gonadal sex determination occurs for at least a dozen species. There are striking similarities in this period among the major taxa with TSD. Examination of TSD in the field indicates that sex ratios of hatchlings are affected by location of the nests, because some nests produce both sexes whereas the majority produce only one sex. Still, more information is needed on how TSD operates under natural conditions in order to fully understand its ecological and conservation implications. TSD may be the ancestral sex-determining condition in reptiles, but this result remains tentative. Physiological investigations of TSD have clarified the roles of steroid hormones, various enzymes, and H-Y antigen in sexual differentiation, whereas molecular studies have identified several plausible candidates for sex-determining genes in species with TSD. This area of research promises to elucidate the mechanism of TSD in reptiles and will have obvious implications for understanding the basis of sex determination in other vertebrates. Experimental and comparative investigations of the potential adaptive significance of TSD appear equally promising, although much work remains to be performed. The distribution of TSD within and among the major reptilian lineages may be related to the life span of individuals of a species and to the biogeography of these species.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Isolation of Salmonella from environmental samples collected in the reptile department of Antwerp Zoo using different selective methods.

AIMS: To evaluate the environmental spread of Salmonella strains in the reptile department of Antwerp Zoo and to compare different isolation methods for Salmonella. METHODS AND RESULTS: One hundred environmental samples were collected in the service sections and public spaces of the reptile department. After pre-enrichment in buffered peptone water (BPW), selective enrichment was performed in Rappaport Vassiliadis Single Component Enrichment Broth (RVS), Selenite Cystine Broth (SEL) and Mueller Kauffman Tetrathionate Broth (MKTTn). Subculturing on Modified Semisolid Rappaport-Vassiliadis (MSRV) Medium, and the combined use of immunomagnetic separation (IMS) and RVS was evaluated. The isolation media used were Hektoen Enteric Agar (HE), Phenol Red Brilliant Green Agar (BG) and Xylose Lysine Decarboxylase Agar (XLD). Salmonella strains were found in 47 samples (47.0%). Most isolations were made on HE after combined IMS/RVS enrichment. Sixty-six Salmonella strains were serotyped, 29 belonged to Salmonella enterica ssp. enterica (I), 3 to ssp. salamae (II), 29 to ssp. arizonae or diarizonae (IIIa/b), 4 to ssp. houtenae (IV) and 1 strain showed autoagglutination. In addition, a 10-year survey (1995-2004) of Salmonella serovars isolated from reptiles at Antwerp Zoo is presented. CONCLUSIONS: A high prevalence of Salmonella strains was noted in the service sections of the reptile department. Only a few isolations were made in the public spaces. Selective enrichment in RVS was the most efficient. In combination with IMS, this method gave an even higher isolation rate than the International Standard method (ISO 6579:2002). SIGNIFICANCE AND IMPACT OF THE STUDY: This study confirms the importance of reptiles as spreaders of Salmonella in their surroundings. The possible infectious risks for zoo personnel and visitors are evaluated. Improved laboratory protocols for the isolation of Salmonella from the environment are suggested.

Animals↗

What transport adaptations enable mammals to absorb sugars and amino acids faster than reptiles?

What digestive adaptations enable mammals to process much more food in much less time with equal or higher digestive efficiency than reptiles and thus to sustain much higher metabolic rates? To answer this question, we measured glucose and proline uptake in small intestinal sleeves of three mammal and three reptile species of similar body size and natural diet. All species exhibit saturable, stereospecific uptake of D-glucose and Na+-dependent L-proline uptake. Passive permeability to glucose is high in hamsters and low in the other species. Uptake increases with temperature up to a maximum around 45-50 degrees C. This temperature dependence may help explain why reptiles bask after meals and why their digestion is impaired if basking is prevented. The total uptake capacity of the small intestine for glucose and proline is seven times higher in mammals than similar-sized reptiles, mainly because the area of mammalian intestine is 4-5.5 times greater. Minor reasons for the higher uptake capacity of mammals are that the transport activity of mammal intestine normalized to quantity of tissue is up to twofold higher and that reptile intestine operates at a lower temperature at night. Vmax for glucose transport varies 10-fold among species, but apparent differences in Km values may be unstirred-layer artifacts. Carrier-mediated uptake of glucose and proline is measurable in the colon of at least three species, but the uptake capacity of the colon is less than 10% of that of the small intestine. An appendix presents a method for measuring the microscopic area of intestines with ridges rather than villi, applies this method to desert iguana intestine, and measures area amplification due to villi in wood rat intestine.

Amino Acids↗

Comparative nephron function in reptiles, birds, and mammals.

Volume and osmolarity of urine produced by kidneys of reptiles, birds, and mammals depend on anatomic relationships among nephrons, epithelial permeability to water controlled by antidiuretic hormone, and, for reptiles and birds, probably on volume flow rate through collecting ducts and excretion of uric acid. Urine volume and volume flow rate through collecting ducts in reptiles and birds depend on number of filtering nephrons controlled by antidiuretic hormone. Mammalian nephrons do not filter intermittently but control of nephron filtration rates in all three vertebrate classes may have important similarities and differences. Uric acid excretion by birds and many reptiles permits excretion of inorganic cations in excess of amounts permitted by osmolarity of urine. This process may require tubular absorption of water without sodium. Such absorption, which has been found in reptilian proximal tubules, may be very important for osmoregulation in all birds and uricotelic reptiles and may provide insight into the mechanism of fluid absorption in mammals. Urea excretion in mammals may be important for enhancing concentrating ability. Much more must be learned about these processes, but similarities and differences among them in the three vertebrate classes may help illuminate details of each.

Animals↗

Detection of mycobacteria and chlamydiae in granulomatous inflammation of reptiles: a retrospective study.

A retrospective study on reptile tissues presenting with granulomatous inflammation was performed to detect the possible presence of mycobacteria and chlamydiae in these lesions. Ninety cases including 48 snakes, 27 chelonians, and 15 lizards were selected. Mycobacteria were detected by Ziehl-Neelsen (ZN) staining and a broad-range polymerase chain reaction (PCR) followed by DNA sequencing. To detect chlamydiae, immunohistochemistry with monoclonal antibodies against chlamydial lipopolysaccharide (LPS) and a Chlamydiales order-specific PCR and sequencing were applied. Acid-fast bacilli were found in 14 cases (15.6%) by ZN staining and in 23 cases (25.6%) by PCR. Sequence analysis revealed the presence of Mycobacteria other than Mycobacterium tuberculosis complex (MOTT). Chlamydial LPS antigen was observed within granulomas from five samples (5.6%), whereas the PCR screen revealed 58 positive cases (64.4%). Of these, 9 cases (10%) showed 98-99% similarity to Chlamydophila (Cp.) pneumoniae and 49 cases (54.4%) displayed a high similarity (88-97%) to the newly described "Chlamydia-like" microorganisms Parachlamydia acanthamoebae and Simkania negevensis. Results from this study confirm, on the one hand, that MOTT are probably the most important infectious etiology for granulomatous inflammation in reptiles. On the other hand, they indicate that chlamydia infects reptiles and that Cp. pneumoniae should be considered an etiological agent of granulomatous lesions of reptiles. Because both MOTT and Cp. pneumoniae are human pathogens, the potential of zoonotic transmission from reptiles to humans has to be considered. In contrast, the significance of Chlamydia-like isolates remains completely open, and further studies are needed to evaluate their role.

Animals↗

Absence of detectable Salmonella cloacal shedding in free-living reptiles on admission to the wildlife center of Virginia.

Salmonellosis is an important reptile-associated zoonotic infection in the United States. Cloacal swabs were collected from reptiles admitted to the Wildlife Center of Virginia, Waynesboro, Virginia, cultured for Salmonella using Hektoen and xylose lysine deoxycholate agars, and inoculated in selenite broth. All three were incubated at 37 degrees C for 18-24 hr. Seventy-five animals were included in the study, representing eight species, 34 eastern box turtles (Terrapene carolina carolina), 14 eastern painted turtles (Chrysemys picta picta), 14 snapping turtles (Chelydra serpentina), 6 black rat snakes (Elaphe obsoleta obsoleta), 2 redbelly turtles (Pseudemys rubriventris), 2 yellowbelly sliders (Trachemys scripta scripta), 2 eastern garter snakes (Thamnophis sirtalis sirtalis), and 1 eastern river cooter (Pseudemys concinna concinna). All cultures were negative for Salmonella spp., which is in contrast to the high prevalence of Salmonella cloacal shedding reported in captive reptiles but similar to previous reports in free-living North American reptiles. We recommend, nonetheless, practicing proper hygiene methods when handling and housing all reptiles.

Animals↗

Effect of regulation and education on reptile-associated salmonellosis.

Reptiles have become increasingly common as domestic pets, and with them reptile-associated Salmonella infections in humans. From 1990 to 2000, a total of 339 reptile-associated Salmonella cases were reported in Sweden. In 1996, as part of its efforts to adapt its import regulations to those of the European Union, Sweden no longer required certificates stating that imported animals were free of Salmonella. A subsequent increase was noted in the incidence of reptile-associated cases from 0.15/100,000 in the period 1990-1994 to 0.79/100,000 in 1996 and 1997. After a public education campaign was begun through the news media, the incidence dropped to 0.46/100,000. Children were the most affected age group among patients (incidence 1.3/100,000). Salmonella enterica serotype Enteritidis was the most frequent serotype (24% of isolates), followed by S. Typhimurium (9% of isolates). Import restrictions and public information campaigns are effective public health measures against reptile-associated salmonellosis.

Adolescent↗

Hygienic evaluation of terraria inhabited by amphibians and reptiles: cryptosporidia, free-living amebas, salmonella.

Amphibians and reptiles are popular pet animals in about 90.000 Austrian households despite their frequently debated capacity to transmit diseases associated with animal keeping. We studied the epidemiological significance of the triangle animal keeper, exotic pet animal, and feed mice by investigating the frequency of three intestinal infestations, caused by cryptosporidia, opportunistic free-living amebas and salmonella, in amphibians and reptiles living in a public vivarium. In addition to recording the first known occurrence of Naegleria australiensis in Austria, and of this species and of Acanthamoeba polyphaga in the feces of reptiles worldwide, we also detected a strong association between Salmonella subspecies I and captive reptiles and between S. sub-species III and free-living lizards. Thus, animal keeper, the exotic animals kept, and the feed mice may constitute an epidemiological pool for the interchange of these infectious agents. This new epidemiological situation may cause an increase of some opportunistic and exotic diseases such as reptile-borne salmonellosis. Despite the perceived benefits of keeping exotic animals in a household, the general public and especially those who have an immunodeficiency must be made aware of the danger of infectious diseases possibly being spread by their pets.

Amoeba↗