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Biomedical subjects

J Baumgartner

Publications and source records attributed to J Baumgartner.

At least 19 recordsLinked to original sources
PubMed2005

Temperature influences on functional response of Coenosia attenuata (Diptera: Muscidae) individuals.

The functional response of single Coenosia attenuta Stein (Diptera: Muscidae) adult females to Drosophila melanogaster (Meigen) adults has been investigated at different but constant temperatures and prey densities. The experiments were conducted in cages over a wide range of temperatures between 12 and 42 degrees C. At each experimental temperature, the number of attacks increases with increasing prey density up to a maximum attack rate referred to as demand rate. A ratio-dependent and demand-driven functional response model was appropriate to describe the attack rate at different temperatures. Both the demand and the search rate linearly increased with increasing temperatures throughout the range. Based on these results, a temperature- and prey density-dependent bidimensional attack rate model was developed and parameterized. The resulting response surface shows that C. attenuata is active over a wide range of temperatures (from approximately 12 to 36 degrees C) and attacks occur up to 42 degrees C. Thus, C. attenuata may be a promising biological control agent in Mediterranean greenhouses. To support this conclusion, further studies including the evaluation of spatial scale effects on the search rate and the consideration of the economically relevant whitefly prey are recommended.

Animals↗
PubMed2004

Foraging behaviour in domestic pigs (Sus scrofa): remembering and prioritizing food sites of different value.

This experiment investigated whether domestic pigs can remember the locations of food sites of different relative value, and how a restricted retrieval choice affects their foraging behaviour. Nine juvenile female pigs were trained to relocate two food sites out of a possible eight in a spatial memory task. The two baited sites contained different amounts of food and an obstacle was added to the smaller amount to increase handling time. On each trial, a pig searched for the two baited sites (search visit). Once it had found and eaten the bait, it returned for a second (relocation) visit, in which the two same sites were baited. Baited sites were changed between trials. All subjects learnt the task. When allowed to retrieve both baits, the subjects showed no preference for retrieving a particular one first (experiment 1). When they were allowed to retrieve only one bait, a significant overall preference for retrieving the larger amount emerged across subjects (experiment 2). To test whether this preference reflected an avoidance of the obstacle with the smaller bait, 15 choice-restricted control trials were conducted. In control trials obstacles were present with both baits. Pigs continued to retrieve the larger bait, indicating they had discriminated between the two food sites on the basis of quantity or profitability and adjusted their behaviour accordingly when the relocation choice was restricted. This suggests for the first time that domestic pigs have the ability to discriminate between food sites of different relative value and to remember their respective locations.

Animals↗
PubMed2001

From 6-t-butylfulvene to highly functionalized five-membered rings.

6-t-Butylfulvene was used as the starting material for asymmetric dihydroxylation. The obtained protected diol (2) was used for several stereoselective functionalizations such as epoxidations, hydroboration, and aminohydroxylation. However, these fulvene derivatives proved to be rather unreactive and gave no conversion under, e.g., palladium (0), catalyses or hydroboration conditions.

Biological Factors↗
PubMed2001

Vagus nerve stimulation and the ketogenic diet.

Antiepileptic drugs are the primary form of treatment for patients with epilepsy. In the United States, hundreds of thousands of people do not achieve seizure control, or have significant side effects, or both. Only a minority of patients with intractable epilepsy are candidates for traditional epilepsy surgery. Vagus nerve stimulation is now the second most common treatment for epilepsy in the United States. Additionally, the ketogenic diet has established itself as a valid treatment. This article discusses the history, mechanism of action, patient selection, efficacy, initiation, complications, and advantages of vagus nerve stimulation and the ketogenic diet.

Adolescent↗
PubMed2001

Population-based screening for rare mutations: high-throughput DNA extraction and molecular amplification from Guthrie cards.

To determine the population-based frequency of a rare mutation (the 121ins2 mutation in the surfactant protein B gene), we developed high-throughput techniques to extract reliably and rapidly amplifiable DNA from Guthrie cards. Using a 3-mm punch from each of 10,044 Guthrie cards obtained from the Missouri Department of Health, we extracted DNA with deionized water by heating in the presence of 2% Chelex in a 96-well format. Average yield of DNA from each punch was 52.6 +/- 21 microg. Using 36mer primers and a 10-microL reaction volume, we amplified a 354-bp fragment of the surfactant protein B gene that contained the mutation and identified the mutation by its susceptibility to restriction enzyme digestion with SfuI. The procedure required 5 h per 96 samples but only 2 h of technician time. The amplification rate on the first attempt was 99.2%. Based on detection of eight individuals heterozygous for the mutation (confirmed by direct sequencing), we estimate the allele frequency to be 0.8/1000 individuals, an estimate not significantly different from previous estimates based on independent methods. High-throughput DNA extraction and amplification will permit establishment of DNA banks as well as efficient estimation of population-based genotype frequency for both rare and common genetic disorders.

Base Sequence↗
PubMed2000

Acute neuroradiologic findings in young children with inflicted or noninflicted traumatic brain injury.

Acute CT/MRI findings were examined in a prospective, longitudinal study of 60 children 0-6 years of age hospitalized for moderate to severe traumatic brain injury (TBI). TBI was categorized as either inflicted (n = 31) or noninflicted (n = 29). Glasgow Coma Scale scores and perinatal history were comparable in both groups. Acute CT/MRI studies were visually inspected by a radiologist blind to group membership. Compared with the noninflicted TBI group, the inflicted TBI group had significantly elevated rates of subdural interhemispheric and convexity hemorrhages as well as signs of pre-existing brain abnormality, including cerebral atrophy, subdural hygroma, and ex vacuo ventriculomegaly. Intraparenchymal hemorrhage, shear injury, and skull fractures were more frequent after non-inflicted TBI. Subarachnoid hemorrhage and infarct/edema occurred with comparable frequency in both groups. Characteristic acute neuroimaging findings of inflicted TBI included multiple extraaxial hemorrhages in addition to the mild atrophy, subdural hygromas, and ventriculomegaly that suggest prior brain abnormality.

Brain Edema↗
PubMed1999

A comparison of magnetoencephalography, MRI, and V-EEG in patients evaluated for epilepsy surgery.

PURPOSE: To determine the efficacy and relative contribution of several diagnostic methods [ictal and interictal scalp and intracranial EEG, magnetic resonance imaging (MRI), and magnetoencephalography (MEG)] in identifying the epileptogenic zone for resection. METHODS: This was a prospective study using a masked comparison-to-criterion standard. Fifty-eight consecutive patients with refractory partial epilepsy from two university comprehensive epilepsy programs were studied. Patients who were evaluated for and underwent epilepsy surgery were recruited. The main outcome measure was the efficacy of each diagnostic method to identify the resected epileptogenic zone, when referenced to surgical outcome. RESULTS: MEG (52%) was second only to ictal intracranial V-EEG in predicting the epileptogenic zone for the entire group of patients who had an excellent surgical outcome (seizure free or rare seizure). In a subanalysis, for patients who had temporal lobe surgery, this same relation was seen (MEG, 57%, ictal intracranial V-EEG, 62%). With extratemporal resection, ictal (81%) and interictal (75%) intracranial EEG were superior to MEG (44%) in predicting the surgery site in those patients with an excellent outcome. Finally, for all patients who had a good surgical outcome, MEG (52%) was better than ictal (33%) or interictal (45%) scalp VEEG in predicting the site of surgery. CONCLUSIONS: These results indicate that MEG is a very promising diagnostic method and raise the possibility that it may obviate the need for invasive EEG in some cases or reduce the length of scalp EEG evaluation in others.

Adolescent↗
PubMed1999

Crush head injuries in infants and young children neurologic and neuropsychologic sequelae.

Neurologic and neuropsychologic sequelae of crush head injury, which is produced by static forces occurring when the head is stationary and pinned against a rigid structure, were studied prospectively in a series of eight children ranging in age from 13 to 32 months. Hospital course, computed tomographic findings, and neurologic and developmental outcomes were examined. All children sustained pronounced cerebral trauma characterized by multiple fractures throughout the calvaria, extra-axial hemorrhages, and parenchymal contusions. Cranial nerve injuries were noted in three and hemiparesis in two of the cases. Two months after the injury, 63% of the children displayed deficits in either IQ or motor functioning. One year after the injury, five of the six children reevaluated had a good recovery. Motor scores were significantly lower than cognitive scores at baseline and showed the greatest degree of improvement over time. Neuropsychologic outcome after brain injury produced by static loading of the head is more favorable than from traumatic brain injury associated with dynamic loading.

Brain Concussion↗
PubMed1998

Biochemical, biophysical, and pharmacological characterization of bacterially expressed human agouti-related protein.

The agouti-related protein gene (Agrp) is a novel gene implicated in the control of feeding behavior. The hypothalamic expression of Agrp is regulated by leptin, and overexpression of Agrp in transgenic animals results in obesity and diabetes. By analogy with the known actions of agouti, these data suggest a role for the Agrp gene product in the regulation of melanocortin receptors expressed in the central nervous system. The availability of recombinant, highly purified protein is required to fully address this potential interaction. A nearly full-length form of AGRP (MKd5-AGRP) was expressed in the cytosolic or soluble fraction of Escherichia coli and appeared as large intermolecular disulfide-bonded aggregates. Following oxidation, refolding, and purification, this protein was soluble, and eluted as a single symmetric peak on RP-HPLC. Circular dichroism studies indicated that the purified protein contains primarily random coil and beta-sheet secondary structure. Sedimentation velocity studies at neutral pH demonstrated that MKd5-AGRP is monomeric at low micromolar concentrations. Mobility shifts observed using SDS-PAGE under reducing and nonreducing conditions for bacterially expressed and mammalian expressed AGRP were identical, an indication of a similar disulfide structure. The purification to homogeneity of a second, truncated form of AGRP (Md65-AGRP) which was expressed in the insoluble or inclusion body fraction is also described. Both forms act as competitive antagonists of alpha-melanocyte stimulating hormone (alpha-MSH) at melanocortin-3 (MC-3) and melanocortin-4 receptors (MC-4). The demonstration that AGRP is an endogenous antagonist with respect to these receptors is a unique mechanism within the central nervous system, and has important implications in the control of feeding.

Agouti Signaling Protein↗
PubMed1998

Pediatric oligodendrogliomas.

Pediatric oligodendrogliomas are infrequently occurring brain tumors and frequently thought of as benign. The literature examining treatment and outcome in this select population is sparse. A retrospective analysis of pediatric oligodendrogliomas treated at MD Anderson Cancer Center between 1973 and 1992 was performed. Oligodendrogliomas were histologically graded according to the method of Smith. Survival data were estimated with Kaplan-Meier curves. Mean follow-up was 39.7 months. Nineteen children had histologically verified oligodendrogliomas and mixed oligodendroglioma/astrocytoma (M:F = 11:8; age range 1-18 years, mean = 13.1). Presenting symptoms included seizures (n = 10), headache (n = 3), visual field defects (n = 2), weakness (n = 2), cranial nerve palsy (n = 1) and decreased school performance (n = 1). All patients underwent craniotomy: 13 subtotal resections, 5 gross total resections and 1 biopsy. Twelve children had adjuvant therapy including radiation (n = 12), chemotherapy (n = 5) or both (n = 5). The 5-year survival was 65%. Seizure frequency was reduced in 30%. Children with oligodendrogliomas do not have a benign course, but younger children (<12 years) have a better prognosis. Histologic classification correlates with survival. Completeness of resection was not found to be a factor relating to survival. No conclusions can be drawn concerning adjuvant therapy because of selection bias.

Adolescent↗
PubMed1996

Simulating development and survival of Aedes vexans (Diptera: Culicidae) preimaginal stages under field conditions.

Ecology and population dynamics of Aedes vexans (Meigen), were studied for 3 yr in southern Switzerland. Demographic data were compiled into single and multicohort stage-frequency lifetables that indicated variability in individual developmental times and losses caused by mortality. The structure of life table matrices suggested an analysis using a timevarying distributed delay model with attrition. Field data then were used to construct and validate a simulation model that input the number of 1st instars and output the number of emerging adults. The delay was the time required to complete development and attrition corresponded to mortality. Under optimal food supply, temperature was the most important driving variable. The model was parameterized with data obtained from laboratory experiments and evaluated with field data. Development and survival of preimaginal Ae. vexans were simulated reasonably well under 2 different pool habitats. Addition of a hydrology component to the model would enhance control operations by predicting hatch rates in the field.

Aedes↗
PubMed1996

[Atypical infection caused by Microsporum gypseum mimicking circumscribed scleroderma].

The authors describe a case of a 31 year old woman who suffered from sclerodermia circumscripta on her right leg. The diagnosis was histopathologically verified. Capillaroscopy and respiratory obstruction were positive. A new lesion appeared on the right arm thus imitating morphea. However, by means of mycological examinations Microsporum gypseum infection was recognized. (Fig. 3, Ref. 13.).

Adult↗
PubMed1993

[Thrombosis of the ascending aorta--a rare cause for recurrent arterial embolism].

A 41-year-old man suffered 3 episodes of transitory left leg ischemia before he was admitted with right brachial artery embolism. The diagnostic evaluation (i/v DSA, CT Scan) revealed a mass in the ascending aorta which was removed under hypothermic cardiocirculatory arrest. Histologically the mass was shown to be a thrombus adjacent to a arteriosclerotic plaque.

Adult↗
PubMed1992

CT and MRI of suprasellar lesions.

The authors report their experience of CT and MRI imaging in the study of suprasellar pathologies. The problems concerning the differential diagnosis between meningioma developed in the suprasellar region and pituitary tumour with suprasellar extension are discussed and illustrated; the demonstration of bone abnormalities (blistering, hyperostosis) is particularly useful for the diagnosis of presellar meningioma. The CT and MRI features of craniopharyngioma are compared; CT, of course, is more reliable than MRI in detecting calcifications; with both methods it may be difficult to visualize the cystic components. Glioma of the chiasma is readily diagnosed by MRI, provided the tumour is not too large. Non-thrombosed suprasellar aneurysms have typical features at CT and MRI. Cystic lesions are easily identified by MRI. The CT and MRI images of inflammatory lesions are not very typical.

Brain Diseases↗
PubMed1992

A technique to examine cock sperm chromosomes using zona-free hamster eggs.

For the first time the visualization of cock sperm chromosomes using zona-free hamster eggs was described. Different variants of egg treatment were tested: varying the duration of incubation of eggs with spermatozoa from 5-6 to 20 h and the cytostatic treatment (colchicine) from 35 min to 9 h, varying the concentration of colchicine from 0.4-400 micrograms/ml and the hypotonic treatment with 0.1% and/or 1.0% sodium citrate or with distilled water from 2-5 to 12 min. In all variants sperm penetration was found, with changes in the head of sperm and the formation of pronucleus but there was no breakdown of the pronuclear envelopes. Only experiments, in which eggs were incubated without colchicine, were successful.

Animals↗