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Biomedical subjects

R A Bennett

Publications and source records attributed to R A Bennett.

At least 19 recordsLinked to original sources
PubMed2006

Direct evidence for the role of centrosomally localized p53 in the regulation of centrosome duplication.

Abnormal amplification of centrosomes is the major cause of mitotic defects and chromosome instability in cancer cells. Centrosomes duplicate once in each cell cycle, and abrogation of the regulatory mechanism underlying centrosome duplication leads to centrosome amplification. p53 tumor suppressor protein is involved in the regulation of centrosome duplication: loss of p53 as well as expression of certain p53 mutants result in deregulated centrosome duplication and centrosome amplification. p53 at least in part depends on its transactivation function to control centrosome duplication, primarily via upregulation of p21 cyclin-dependent kinase (CDK) inhibitor, which prevents untimely activation of CDK2/cyclin E, a key initiator of centrosome duplication. However, numerous studies have shown the presence of p53 at centrosomes, yet the role of the centrosomally localized p53 in the regulation of centrosome duplication had been enigmatic. Here, we comparatively examined wild-type p53 and p53 mutants that are transactivation(+)/centrosome-binding(-), transactivation(-)/centrosome-binding(+) and transactivation(-)/centrosome-binding(-) for their abilities to control centrosome duplication. We found that the transactivation(+)/centrosome-binding(-) and transactivation(-)/centrosome-binding(+) mutants suppress centrosome duplication only partially compared with wild-type p53. Moreover, the transactivation(-)/centrosome-binding(-) mutant almost completely lost the ability to suppress centrosome duplication. These observations provide direct evidence for the centrosomally localized p53 to participate in the regulation of centrosome duplication in a manner independent of its transactivation function in addition to its transactivation-dependent regulation of centrosome duplication.

Animals↗
PubMed2001

Key role of a downstream specificity protein 1 site in cell cycle-regulated transcription of the AP endonuclease gene APE1/APEX in NIH3T3 cells.

Abasic (apurinic/apyrimidinic or AP) sites are a frequent type of DNA damage that threatens genetic stability. The predominant mammalian enzyme initiating repair of AP sites is the Ape1 AP endonuclease (also called Apex or Hap1), which also facilitates DNA binding by several transcription factors (Ref1 activity). We found that expression of the APE1 gene was coordinated with the cell cycle in murine NIH3T3 cells: APE1 mRNA levels rose after the G(1)-S transition and peaked approximately 4-fold higher in early to mid-S phase. The increased APE1 mRNA was the result of transcriptional activation rather than increased mRNA stability. Fusions of various APE1 promoter fragments to the chloramphenicol acetyltransferase CAT reporter gene indicated that APE1 expression depends on two transcription factor Sp1 binding sites within the promoter region. Mutation of these sites or of two CCAAT elements within the APE1 promoter, in conjunction with protein binding studies, demonstrated their specific roles. The Sp1 site upstream of the transcription start, together with an adjacent CCAAT element, establishes a protein-DNA complex required for basal transcription of APE1. The Sp1 site downstream of the transcription start was required for the response to cell growth. Because Ape1 is a dual function enzyme, its cell cycle-dependent expression might affect both DNA repair and the activity of various transcription factors as a function of the cell cycle.

3T3 Cells↗
PubMed2001

Plasma concentration of ionized calcium in healthy iguanas.

OBJECTIVE: To measure plasma concentration of ionized calcium in healthy green iguanas. DESIGN: Prospective study. ANIMALS: 9 juvenile and 21 (10 male, 11 female) adult iguanas. PROCEDURE: Blood samples were obtained from each iguana, and plasma calcium, glucose, phosphorus, uric acid, total protein, albumin, globulin, potassium, and ionized calcium concentrations, aspartate transaminase (AST) activity, and pH were measured. Heparinized blood was used for measurement of ionized calcium concentration and blood pH. A CBC was also performed to assess the health of the iguanas. RESULTS: Significant differences were not detected among the 3 groups (juveniles, males, and females) with regard to ionized calcium concentration. Mean ionized calcium concentration measured in blood was 1.47 +/- 0.105 mmol/L. Significant differences were detected between juveniles and adults for values of phosphorus, glucose, total protein, albumin, globulin, and AST activity. CONCLUSIONS AND CLINICAL RELEVANCE: Ionized calcium concentration provides a clinical measurement of the physiologically active calcium in circulation. Evaluation of physiologically active calcium in animals with suspected calcium imbalance that have total plasma calcium concentrations within reference range or in gravid animals with considerably increased total plasma calcium concentrations is vital for determining a therapeutic plan. Accurate evaluation of calcium status will provide assistance in the diagnosis of renal disease and seizures and allow for better evaluation of the health status of gravid female iguanas.

Age Factors↗
PubMed2001

Morphologic and cytochemical characteristics of blood cells and hematologic and plasma biochemical reference ranges in green iguanas.

OBJECTIVE: To determine blood cell morphologic characteristics and hematologic and plasma biochemical reference ranges for iguanas housed in a warm indoor and outdoor environment with regular exposure to direct sunlight. DESIGN: Original study. ANIMALS: 51 clinically normal iguanas (18 males, 25 females, and 8 juveniles) housed in 3 Florida locations. PROCEDURE: Blood was collected from the coccygeal or ventral abdominal vein. Any samples that had obvious hemolysis or clot formation were not used. Leukocyte counts were determined manually; other hematologic values were obtained by use of a commercially available cell counter. Plasma biochemical values were determined by use of a spectrophotometric chemistry analyzer. Blood smears were stained with Wright-Giemsa and cytochemical stains for morphologic and cytochemical evaluation. RESULTS: Hematologic ranges were generally higher in this study than previously reported. Thrombocytes were variable in appearance between individuals and sometimes difficult to distinguish from lymphocytes on a Wright-Giemsa preparation. Concentrations of calcium, phosphorus, total protein, globulins, and cholesterol were significantly higher, and the albumin:globulin ratio was significantly lower, in healthy gravid females than in male or nongravid female iguanas. Nongravid females had significantly higher calcium and cholesterol concentrations, compared with males. The calcium:phosphorus ratio was > 1 in all iguanas. Gravid females had a calcium phosphorus product ranging between 210 and 800. Intracytoplasmic inclusions were identified within the erythrocytes of some iguanas. CONCLUSIONS AND CLINICAL RELEVANCE: Hematologic ranges for iguanas in this study are higher than those reported for iguanas. Sex and age of the iguana should be considered when evaluating biochemical values. Healthy ovulating and gravid females may have significantly increased electrolyte and protein concentrations, but maintain a calcium:phosphorus ratio > 1.

Age Factors↗
PubMed2001

Spontaneous conception in the presence of stage IIIC endometrioid ovarian cancer.

OBJECTIVE: To describe a rare case of spontaneous conception in a patient with a preexisting metastatic ovarian cancer. DESIGN: Case report. SETTING: University hospital. PATIENT(S): A 39-year-old Asian woman who conceived while undergoing an evaluation for primary infertility and newly detected bilateral adnexal masses. INTERVENTION(S): Staging laparotomy and total abdominal hysterectomy and bilateral salpingo-oophorectomy. MAIN OUTCOME MEASURE(S): Anatomic pathology diagnosis. RESULT(S): Blighted ovum and stage IIIC endometrioid adenocarcinoma of ovary. CONCLUSION(S): Metastatic ovarian cancer does not prevent either spontaneous ovulation or spontaneous conception.

Abortion, Missed↗
PubMed2001

Detection of antibodies to a pathogenic mycoplasma in American alligators (Alligator mississippiensis), broad-nosed Caimans (Caiman latirostris), and Siamese crocodiles (Crocodylus siamensis).

An epidemic of pneumonia with fibrinous polyserositis and multifocal arthritis emerged in captive American alligators (Alligator mississippiensis) in Florida, United States, in 1995. Mycoplasma alligatoris sp. nov. was cultured from multiple organs, peripheral blood, synovial fluid, and cerebrospinal fluid of affected alligators. In a subsequent experimental inoculation study, the Henle-Koch-Evans postulates were fulfilled for M. alligatoris as the etiological agent of fatal mycoplasmosis of alligators. That finding was remarkable because mycoplasmal disease is rarely fatal in animals. An enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies produced by alligators in response to M. alligatoris exposure was developed by using plasma obtained from naturally infected alligators during the original epidemic. The assay was validated by using plasma obtained during an experimental dose-response study and applied to analyze plasma obtained from captive and wild crocodilian species. The ELISA reliably detected alligator seroconversion (P < 0.05) beginning 6 weeks after inoculation. The ELISA also detected seroconversion (P < 0.05) in the relatively closely related broad-nosed caiman Caiman latirostris and the relatively distantly related Siamese crocodile Crocodylus siamensis following experimental inoculation with M. alligatoris. The ELISA may be used to monitor exposure to the lethal pathogen M. alligatoris among captive, repatriated, and wild crocodilian species.

Alligators and Crocodiles↗
PubMed2001

Experimental inoculation of broad-nosed caimans (Caiman latirostris) and Siamese crocodiles (Crocodylus siamensis) with Mycoplasma alligatoris.

An outbreak of mycoplasmosis caused by Mycoplasma alligatoris resulted in the death or euthanasia of 60 American alligators (Alligator mississippiensis) from a population of 74 captive bull alligators in Florida in 1995. The natural reservoir, routes of transmission, and host range of M. alligatoris are unknown. This study was undertaken to determine whether crocodilian species other than American alligators are susceptible to M. alligatoris. Six broad-nosed caimans (Caiman latirostris) and six Siamese crocodiles (Crocodylus siamensis) were experimentally inoculated with 10(6) colony forming units (CFU) of M. alligatoris instilled through the glottis. Two caimans and two crocodiles were used as negative controls. Six and four American alligators were used as positive and negative controls, respectively. Three of six (50%) inoculated caimans died within 10 wk postinoculation (PI) of severe mycoplasmosis. Gross necropsy, histopathologic, and culture results were similar for broad-nosed caimans and American alligators. None of the inoculated Siamese crocodiles developed mycoplasmosis, though M. alligatoris was isolated from the tonsils in three of six (50%) animals at necropsy. All the inoculated crocodilians that survived showed significant seroconversion by 6-8-wk PI (P < 0.05). The infective dose 50% (ID50) and lethal dose 50% (LD50) of M. alligatoris for the broad-nosed caiman are 10(6) CFU when instilled through the glottis, which is similar to that of the American alligator. Although the host range of M. alligatoris is not restricted to the American alligator, the organism does not appear to be pathogenic for Siamese crocodiles. Other species of crocodilians may be susceptible to infection with M. alligatoris, and this organism should be considered when the rapid onset of clinical signs of pneumonia, polyarthritis, pericarditis, and death occur.

Alligators and Crocodiles↗
PubMed2001

Pathology of experimental mycoplasmosis in American alligators.

Mycoplasma alligatoris was the suspected etiology of an epidemic of acute multisystemic inflammatory disease which emerged in captive American alligators (Alligator mississippiensis) in Florida (USA) in 1995. In an experimental inoculation study conducted from April through October 1999, 18 alligators were inoculated with 10(2), 10(4), or 10(6) colony forming units (CFU) of M. alligatoris by instillation into the glottis. As early as 1 wk post-inoculation (PI), mycoplasma were cultured from blood of three of six alligators inoculated with 10(6) CFU. Two of those died and the third was euthanatized within 4 wk PI. Necropsy gross findings included fibrinous polyserositis and polyarthritis. Histopathologic changes in affected individuals included pulmonary edema, interstitial pneumonia, pericarditis, myocarditis, meningitis, and synovitis. Mycoplasma were cultured quantitatively in high numbers from trachea, lung, coelomic cavity, liver, spleen, interior of pericardial sac, heart, blood, brain, and limb joints. In alligators inoculated with 10(6) CFU, heterophilia and moderate hyperglycemia peaked about 4 wk PI, and seroconversion occurred by 6 to 8 wk PI. Necropsy gross and histologic findings were generally unremarkable for the surviving alligators inoculated with 10(6) CFU, alligators inoculated with 10(2) or 10(4) CFU, and four uninoculated control alligators. Mycoplasma were not cultured at any time point from those alligators. The findings confirm that M. alligatoris can cause fulminant inflammatory disease and rapid death of alligators.

Acute Disease↗
PubMed2000

Individual variability in the zinc inducibility of metallothionein-IIA mRNA in human lymphocytes.

The metallothionein-III gene (MT-IIA) is a major member of the human MT gene family. Metallothioneins (MTs) are low-molecular-weight, cysteine-rich proteins that bind and detoxify heavy metals. At least two different MT-IIA polymorphisms have been identified in humans, one or both of which may affect susceptibility to metal toxicity. The purpose of this study was to investigate whether these different genotypes affect the inducibility of MT-IIA mRNA in human lymphocytes treated with zinc (Zn), the major known inducer of MT-IIA in vitro. Fresh lymphocytes obtained from 16 healthy volunteers, aged 23-38 yr, were genotyped for the MT-IIA gene and tested for expression. A 43.5-bp HindIII-Taql fragment of the MT-IIA promoter was used to probe for the two known polymorphisms (a 7.8-kb vs. a 5.3-kb fragmnent, and a 1.7-kb vs. a 1.6-kb fragment). The allele frequencies of the 16 subjects were 14%, for 5.3-kb allele and 19% for 1.6-kb allele. In Northern blotting experiments, MT-II mRNA levels were induced over a wide range of Zn concentrations during 2-h exposures; specifcally, levels increased by 9- to 115-fold with exposure to 100 microM ZnCl, and by 16- to 311-fold with exposure to 200 microM ZnCl2. However, no significant differences in MT-IIA inducibility were found between the 7.8/5.3-kb allele pair (n = 4) and the 7.8/7.8-kb allele pair (n = 12) or between the 1.7/1.6-kb allele pair (n = 5) and the 1.7/1.7-kb allele pair (n = 11). Thus. MT-IIA is strongly inducible by Zn in human lymphocytes, but individual variations exceed those that can be attributed to the known promoter-region polymorphisms.

Adult↗
PubMed2000

Ureterotomy for removal of two ureteroliths in a parrot.

A 21-year-old male double-yellowheaded Amazon parrot was referred because of possible urolithiasis. The bird had strained to void since it was young, and recently, signs of depression and inappetence had appeared. Radiography revealed 2 mineralized opacities in the left caudal portion of the celomic cavity. A left lateral celiotomy revealed that the left ureter was dilated and contained a calculus, which was later determined to be composed of monosodium uric acid crystals and proteinaceous material. The second mineralized mass could not be located at that time, but was detected in the caudal aspect of the celomic cavity after surgery by use of radiography. Manual attempts to maneuver the uterolith from the ureter through the cloaca were unsuccessful. Five days after the initial surgery, the uterolith was removed by cloacotomy and ventral midline laparotomy. Excretory urography performed 10 and 31 days after surgery revealed that the left ureter was homogeneously opacified and gradually decreased to 3 to 6 mm in diameter. The bird remained healthy and seemed to strain less severely during voiding. Nonspecific signs associated with ureteroliths may result in delay in diagnosis. Surgical removal of ureteroliths may be an effective treatment for this uncommon condition, but it is complicated by certain anatomic features of birds and may result in ureteral stricture.

Animals↗
PubMed2000

Preparation and equipment useful for surgery in small exotic pets.

Because many exotic pets are so small, the instrumentation and equipment used for surgery are different from in larger animals. Magnification greatly improves the surgeon's ability to accomplish surgeries in small patients and helps to provide hemostasis because small amounts of blood are significant in these tiny patients. Microsurgical instrumentation is important to allow for proper tissue handling and suture placement. Various other considerations, instrumentation, and equipment are useful when performing surgery on small exotic pets.

Animal Diseases↗
PubMed2000

Nonreproductive surgery in reptiles.

As reptiles have gained popularity as pets, veterinarians are more frequently called on to perform surgical procedures on these pets. Veterinarians must have a basic understanding of the anatomic and physiologic differences between reptilian and mammalian companion animals. This article reviews some basic points about reptilian anatomy and physiology that are important to consider when performing surgery on reptilian patients. This article covers approaches to the coelomic cavity in the different groups of reptiles and some basic concepts regarding surgery on different, nonreproductive systems in these reptiles.

Animal Diseases↗
PubMed2000

Thoracic vertebral chordoma in a domestic ferret (Mustela putorius furo).

A castrated adult male 1.0-kg domestic ferret (Mustela putorius furo) was referred for evaluation of a mass of >5 mo duration that was associated with the thoracic spine. The ferret had motor dysfunction and no conscious proprioception or pain perception in either hind limb. Segmental reflexes were present. Survey radiography, myelography, and magnetic resonance imaging showed a mass involving the ninth and 10 thoracic vertebrae and compressing the spinal cord. Decompressive surgery was performed, but clinical signs persisted. A diagnosis of chordoma was made using histopathology and immunohistochemistry. This is the first reported case of a chordoma involving the thoracic vertebrae in a domestic ferret.

Animals↗
PubMed2000

Intestinal volvulus and stricture associated with a leiomyoma in a green turtle (Chelonia mydas).

A previously stranded 30-kg female green turtle (Chelonia mydas) was referred to the Veterinary Medical Teaching Hospital at the University of Florida following a 2-mo history of anorexia, intermittent regurgitation, decreased fecal production, and positive buoyancy of the right side. Radiographs confirmed gaseous distension of bowel loops suggestive of intestinal obstruction. The coelom was surgically approached through a plastron osteotomy, and a 540 degrees volvulus of the small intestine was identified and derotated. An intestinal stricture was present at the site of the volvulus, and segments of bowel orad to the stricture were greatly distended. Following resection of abnormal bowel, the osteotomy was stabilized using self-tapping screws and figure-eight wire, and the defect was sealed with fiberglass cloth and fast-drying epoxy resin. A leiomyoma associated with the focal stricture was identified by histology. Appetite and defecation returned to normal. Six months after surgery, the turtle had regained normal buoyancy and showed no further clinical signs of gastrointestinal obstruction.

Analgesics, Non-Narcotic↗
PubMed2000

Morbidity and mortality associated with a new mycoplasma species from captive American alligators (Alligator mississippiensis).

Nine of 74 American alligators (Alligator mississippiensis) from a captive Florida herd of 3-4-m-long, 200-350-kg, adult males greater than 30 yr of age died within a 10-day period during 1995. Nonspecific clinical signs included anorexia, lethargy, muscle weakness, paraparesis, bilateral white ocular discharge, and various degrees of periocular, facial, cervical, and limb edema. Pneumonia, pericarditis, and arthritis were found on postmortem evaluation of the spontaneously dead and euthanatized alligators. Rapidly growing mycoplasmas were identified by culture, and mycoplasma nucleotide sequences were identified by polymerase chain reaction testing of fresh lung and synovial fluid from an affected alligator. Culture of banked frozen lung from necropsy specimens and fresh lung and fresh synovial fluid from newly affected alligators confirmed the presence of a new mycoplasma species in seven of eight individuals. Oxytetracycline was administered, but related deaths continued for 6 mo until only 14 of the initial alligators remained. An enzyme-linked immunosorbent assay to detect antibody was developed, and the organism was transmitted experimentally to naive juvenile alligators, although the source of the organism, Mycoplasma sp. (ATCC 700619), has not been identified. The alligator isolate is a novel species in the mycoplasma family because its nucleotide sequence does not match those of over 75 characterized mycoplasma species. Such factors as population density, animal age, and mycoplasmal virulence likely contributed to the course of disease.

Alligators and Crocodiles↗
PubMed2000

T-cell-rich B-cell lymphoma in a ring-tailed lemur (Lemur catta).

A 13-yr-old ring-tailed lemur (Lemur catta) was evaluated for depression, anorexia, polyuria, and polydipsia. The lemur was in poor body condition and was anemic, hypoalbuminemic, and hyponatremic. Cytologic examination of aspirates of the spleen, liver, and bone marrow and histopathologic examination of liver and bone marrow biopsies revealed a disseminated round cell tumor. After euthanasia, necropsy revealed hepatomegaly, splenomegaly, and mesenteric lymphadenomegaly. Neoplastic cells were present within the spleen, liver, kidneys, multiple lymph nodes, bone marrow, lung, small intestine, pancreas, and testicle and were composed of large anaplastic round cells in a background of small well-differentiated lymphocytes. Immunohistochemical analysis revealed that the small well-differentiated lymphocytes labeled for the anti-human T-cell marker, CD3, and the large anaplastic round cells labeled with the anti-human B-cell marker, CD79a. On the basis of the immunohistochemical staining results and morphologic appearance, a diagnosis of a T-cell-rich B-cell lymphoma was made.

Animal Diseases↗
PubMed2000

Electrodiagnostic evaluation of peripheral nerve function in rheas and barred owls.

OBJECTIVE: To establish reference values for electrodiagnostic evaluation of peripheral nerve function in birds. ANIMALS: 6 rheas and 6 barred owls. PROCEDURE: Birds were anesthetized with propofol or isoflurane in oxygen. Using a computer-based electromyograph system and needle electrodes for stimulation and recording, electromyography (EMG) was performed on the pectoral, biceps brachialis, and gastrocnemius muscles, and evoked EMG was performed on the tibial and ulnar nerves. Motor nerve conduction velocity (MNCV) was calculated. Repetitive stimulation was performed on these 2 nerves. Late F waves were recorded for each nerve, when possible. RESULTS: Activity was evident during insertion of the electrodes, but muscles tested were electrically quiescent after spontaneous EMG. Motor nerve conduction velocity was faster in the tibial nerve than ulnar nerve but did not differ significantly between species. Mean +/- SEM MNCV was 132.3+/-7.8 m/s for the tibial nerve and 59.7+/-7.8 m/s for the ulnar nerve. A significant difference was not observed in responses at the fourth or ninth stimulation during repetitive stimulation. Subsequent to the initial stimulation, amplitudes were +/-22.7% of the initial motor potential amplitude. Recorded F waves were inconsistent, which may have been associated with technique. CONCLUSIONS AND CLINICAL RELEVANCE: Reference range (mean +/-2 SEM) for MNCV was 34.1 to 75.3 m/s for the ulnar nerve and 116.7 to 147.9 m/s for the tibial nerve in barred owls and rheas. After repetitive stimulation, motor potential amplitudes may be +/-22.7% of the initial amplitude response.

Animals↗