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Biomedical subjects

M Opitz

Publications and source records attributed to M Opitz.

At least 19 recordsLinked to original sources
PubMed2004

Comparison of unreamed nailing and external fixation of tibial diastases--mechanical conditions during healing and biological outcome.

Locked intramedullary nailing and external fixation are alternatives for the stabilization of tibial shaft fractures. The goal of this study was to determine to what extent the mechanical conditions at the fracture site influence the healing process after unreamed tibial nailing compared to external fixation. A standardized tibial diastasis was stabilized with either a locked unreamed tibial nail or a monolateral fixator in a sheep model. Interfragmentary movements and ground reaction parameters were monitored in vivo throughout the healing period. After sacrifice, the tibiae were examined mechanically and histologically. Bending angles and axial torsion at the fracture site were larger in the nail group within the first five weeks post-operatively. Unlike the fixator group, the operated limb in the nail group did not return to full weight bearing during the treatment period. Mechanical and histomorphometrical observations showed significantly inferior bone healing in the nail group compared to the fixator group. In this study, unreamed nailing of a tibial diastasis did not provide rotational stability of the osteosynthesis and resulted in a significant delay in bone healing.

Animals↗
PubMed2003

5-HT1A responsivity in patients with panic disorder before and after treatment with aerobic exercise, clomipramine or placebo.

Blunted neuroendocrine and physiological responses to the selective 5-HT(1A) receptor agonist, ipsapirone, have been observed in patients with panic disorder and/or agoraphobia (PDA). In order to examine whether this hyporesponsiveness to ipsapirone is modified by pharmacological or non-pharmacological therapeutic interventions, challenges with an oral dose of ipsapirone (0.3 mg/kg) and placebo were performed in patients with PDA before and after 10 weeks of treatment with clomipramine, aerobic exercise and placebo. Before treatment, administration of ipsapirone was followed by significant increases of cortisol, anxiety and other psychopathological symptoms in comparison to the placebo challenge. In addition, a significant decrease of body temperature was observed. After the 10-week treatment period, the psychological responses to ipsapirone were significantly reduced in the clomipramine and the exercise group. In contrast, there was a non-significant trend towards higher cortisol responses after clomipramine and exercise treatment. The hypothermic response to ipsapirone was significantly reduced by clomipramine treatment. In conclusion, our results demonstrate that effective treatment of panic disorder has divergent effects on the psychological, neuroendocrine and temperature responses to ipsapirone.

Adolescent↗
PubMed2000

Increased psychological responses and divergent neuroendocrine responses to m-CPP and ipsapirone in patients with panic disorder.

In patients with panic disorder and /or agoraphobia (PDA) an increased sensitivity of central 5-HT2C receptors and a decreased responsiveness of 5-HT1A receptors has been postulated. In the present study, neuroendocrine challenges were performed using oral doses of the non-selective 5-HT2C agonist m-chlorophenylpiperazine (m-CPP) (0.4 mg/kg), the selective 5-HT1A antagonist ipsapirone (0.3 mg/kg), and placebo in 40 patients with PDA and 12 healthy controls in order to compare 5-HT2C and 5-HT1A-specific psychobehavioural and neuroendocrine response patterns. At baseline, all psychobehavioural variables and the plasma concentration of noradrenaline (NE) were significantly increased in the patient group compared to the controls. The administration of m-CPP or ipsapirone was followed by comparable psychological symptoms and, in 55% of all patients, panic attacks. In comparison to the control subjects, patients were characterized by significantly higher psychological reactions to both challenge agents and a significantly higher NE response to m-CPP. In the patient group, there was also a trend towards an increased cortisol response after administration of m-CPP and a decreased cortisol and hypothermia response after administration of ipsapirone compared to the control group. The neuroendocrine findings of our study support earlier reports of opposite changes in the responsiveness of 5-HT2C and 5-HT1A-related receptors in PDA patients. The behavioural hypersensitivity to both, m-CPP and ipsapiron, shows that the provocation of anxiety and other psychological symptoms might be influenced by

Adolescent↗
PubMed2000

67Ga-citrate and 99Tcm-MDP for estimating the severity of vertebral osteomyelitis.

The aim of this study was to evaluate the roles of 67Ga-citrate and 99Tcm-methylene diphosphonate (99Tcm-MDP) planar and single photon emission tomographic (SPET) imaging in patients with vertebral osteomyelitis. Thirty patients (22 females, 8 males) aged 62.7 +/- 16.4 years (mean +/- s) were enrolled prospectively between May 1995 and May 1998. The patients had been on antibiotics for 7 +/- 4 weeks prior to the study. Histology was available for all but nine patients with mild infections, who were evaluated by a combination of magnetic resonance imaging (MRI), clinical and laboratory tests. 67Ga-citrate (185 MBq) and three-phase bone (555 MBq 99Tcm-MDP) planar and SPET imaging were performed in all patients, together with MRI as a comparison. In total, 67 infectious foci were detected. Based on histology, there were four cases of severe, 13 cases of moderate and four cases of mild osteomyelitis; nine mild infections were also classified by the combination of MRI, clinical and laboratory results. Combined MRI and 67Ga-citrate SPET correctly classified all patients; MRI detected all 67 infectious foci, whereas 67Ga-citrate SPET identified 54 only. False-negative results were seen with all other modalities, especially in cases of mild and moderate infection. 67Ga-citrate SPET identified unsuspected cases of endocarditis (n = 2), paravertebral abscess (n = 1), subaxillary soft tissue abscess (n = 1) and rib osteomyelitis (n = 1). For 67Ga-citrate SPET, the target-to-background ratio was 2.24 +/- 0.31, 1.76 +/- 0.07 and 1.30 +/- 0.18 for severe, moderate and mild osteomyelitis, respectively. Significant differences were noted between severe and moderate infection (P = 0.0051) and between severe and mild infection (P < 0.0001); that between moderate and mild infection was non-significant. For 99Tcm-MDP planar and SPET imaging, and for planar 67Ga-citrate imaging, there was no correlation with severity. We conclude that 67Ga-citrate SPET is able to identify vertebral osteomyelitis and detect additional sites of infection. It can also aid in determining the severity of infection and, potentially, the response to therapy.

Aged↗
PubMed1999

Genomic relationships of the North American isolate of infectious salmon anemia virus (ISAV) to the Norwegian strain of ISAV.

Nucleotide and deduced amino acid sequences were determined for a 436 bp reverse transcriptase-polymerase chain reaction (RT-PCR) cDNA fragment from genome segment 8 and a 1151 bp RT-PCR cDNA fragment from genome segment 2 of the North American isolate of infectious salmon anemia virus (ISAV) and compared to the published sequences of Norwegian isolates of ISAV. The North American ISAV isolate exhibited 82.9% identity with the Sotra 92/93 ISAV isolate from Norway in the partial cDNA sequence of genome segment 2, which encodes a polymerase component protein (PB1). The North American ISAV exhibited 88 and 89% identity with 2 partial cDNA sequences of genome segment 8 (nonstructural, NS, gene) reported for the Glesvaer/2/90 isolate from Norway. The North American ISAV exhibited 96.6% similarity with the Sotra 92/93 ISAV isolate from Norway in the deduced amino acid sequences of the PB1 protein. The deduced amino acid sequence of the protein encoded in the partial cDNA fragment of open reading frame (ORF) 1 of genome segment 8 of the North American ISAV exhibited only 71.2 and 66.7% similarity with the 2 sequences of the Norwegian Glesvaer/2/90 isolate. However, the North American ISAV isolate exhibited 96.2 and 87.2% similarity with the 2 sequences of the Norwegian Glesvaer/2/90 isolate in the deduced amino acid sequences of the protein encoded in the partial cDNA of ORF 2. Comparison of these partial cDNA nucleotide and deduced amino acid sequences confirmed that the North American isolate is ISAV. However, the differences observed in these genomic sequences suggest that the North American isolate may represent a distinct genomic variant from the previously described Norwegian strains.

Amino Acid Sequence↗
PubMed1999

Participation of angiotensin receptors in acute hypoxia in mice. II. Effects of angiotensin II nonpeptide receptor ligands losartan (DuP-753) and PD-123319.

The effects of intracerebroventricularly (i.c.v.) administered angiotensin nonpeptide receptor ligands losartan (DuP-753) and PD-123319 and their interactions with Ang II were examined on acute anoxic hypoxia in male mice. Results showed that losartan and PD-123319 exerted antihypoxic effects including increased latency to convulsive seizures and survival time and pretreatment with both drugs enhanced Ang II-increased survival time. Taken together, the results suggest that the antihypoxic effect of losartan and PD-123319 is most likely due to action on brain AT1 and AT2 receptors with both drugs behaving as partial agonists.

Acute Disease↗
PubMed1997

The mast cell products histamine and serotonin stimulate and TNF-alpha inhibits the proliferation of murine epidermal keratinocytes in situ.

To better characterize the proposed growth modulatory functions of mast cells and their products in the regulation of epidermal homeostasis, we have assessed keratinocyte proliferation by incorporation of [3H]thymidine in murine skin organ cultures after incubation with different concentrations of histamine, serotonin or TNF-alpha. Both histamine and serotonin significantly stimulate the proliferation of keratinocytes as compared to controls (P < 0.001), reaching maxima within a range from micro- to nanomolar concentrations. Even at subnanomolar concentration, TNF-alpha significantly inhibits the incorporation of labelled thymidine by epidermal keratinocytes in murine skin organ culture (P < 0.001). These observations support the concept of mast cell products as modulators of keratinocyte proliferation, and suggest a role for mast cells in the regulation of epidermal tissue turnover under physiological conditions.

Animals↗
PubMed1996

[Skin manifestations in leishmaniasis in dogs].

In 23 dogs with clinically apparent leishmaniosis the observed skin lesions were analyzed with respect to appearance, type and localization. The diagnosis could be established in 22 cases by cytological or histological demonstration of the parasite, positive serodiagnosis and typical clinical findings. The following lesions-in order of frequency-were found on the mucous membranes and the skin including foot pads and nails as well as on the mucocutaneous junctions: 1) desquamation with formation of characteristical light scales, 2) localized or symmetrical alopezia, 3) erythema, 4) ulceration and depigmentation was seen especially at the acrae, 5) granulomatous nodules and pustular dermatitis were less common. Hyperkeratosis of the foot pads, onychogriposis and onychorrhexia occurred at the paws. These various cutaneous manifestations of leishmaniosis should be considered in the differential diagnosis of canine skin disease.

Animals↗
PubMed1995

Effects of angiotensin II on brain monoamines in nonhypoxic and hypoxic mice.

The effects of angiotensin II (ATII) administered intracerebroventricularly (ICV, acute) and subcutaneously (SC, acute and chronic) on acute hypoxia (asphyctic and hemic), and on the forebrain concentrations of monoamines dopamine (DA), norepinephrine (NE), and serotonin (5-HT) in male mice were studied. ATII in both routes of administration exerted a decrease of the latency to hypoxia-induced convulsions. ATII slightly reduced the brain levels of DA and NE, and did not change those of 5-HT in hypoxic mice. ATII significantly reduced DA and 5-HT concentrations in nonhypoxic (normoxic) mice. Taken together, the results suggest that ATII-induced increase of susceptibility to hypoxia is accompanied by slight alterations in the brain monoamine metabolism.

Analysis of Variance↗
PubMed1993

Treatment of grade III osteonecrosis of the femoral head with a Charnley/Bicentric hemiarthroplasty.

Thirty-eight hips with Charnley/Bicentric hemiarthroplasties were reviewed. Preoperatively all hips had a Grade III osteonecrosis (Arlet & Ficat) of the femoral head. Follow-up ranged from 42 to 72 months with a mean of 56 months. The mean age was 36 years (range 16-52 years). Three hips with gross loosening of the femoral prosthesis were revised to a cementless total hip replacement: a further two hips exhibited radiological changes indicative of loosening and pending failure. In one hip with progressive loss of joint space and secondary degenerative changes the Bicentric cup was revised to a cemented Charnley component. Acetabular migration was not encountered. Six of 38 hips (15.8%) were thus considered failures. The mean total movement from full abduction to full adduction at the cup-acetabular articulation was 21 degrees, compared to 14 degrees at the inner component articulation. The results of cemented femoral components are predictably unfavourable in this young age group. However, the double articulation of the bipolar cup offers an acceptable method of treatment for this grade of osteonecrosis in the medium term.

Adolescent↗
PubMed1993

[Applied psychoacoustics in space flight].

Simulation free field hearing by head phones by means of digital filter technics was used to investigate directional hearing and audiocinetic vection in microgravity. Our data showed basic informations for the understanding of the reciprocal influence of vestibular and auditory inputs for dynamic orientation. The technical equipment of free field hearing simulation by headphones and the performed experiments are described in detail. Furthermore the new established technology is discussed in terms of the value in psychoacoustic research as well as in clinical practice.

Auditory Perception↗
PubMed1993

[Myopathy due to potassium deficiency in eight cats and a dog].

Eight cats and one dog with signs of cervical ventroflexion, reluctance to walk, a stiff and stilted gait and muscle weakness are introduced. Though blood potassium concentration was very low (< 3.0 mval/l) in one cat and the dog only, a potassium depletion myopathy was assumed as the cause of these symptoms. Two of three cats had elevated values of the urinary fractional potassium excretion compared to ten healthy cats. Blood creatinine values were within normal ranges. Five of seven cats had elevated creatine kinase values. All animals improved after potassium substitution. Causes of potassium depletion are discussed and differential diagnoses of myopathies are briefly mentioned.

Animals↗
PubMed1990

[Stress hyperglycemia in cats].

It may be difficult to differentiate the possible causes of hyperglycemia in the cat. The following investigation was on transient hyperglycemia in 320 cats. The frequency and degree of stress-hyperglycemia and its relation to different types of primary diseases was proven. Animals with overt diabetes mellitus or pancreatic diseases were not included in this study. Plasma glucose was analyzed with the o-Toluidine- or with the glucose oxidase-method. Plasma immune-reactive insulin (IRI) was estimated by RIA. A glucose concentration of greater than or equal to 140 mg/dl (7.77 mmol/l) in the fasted animal was defined as hyperglycemia. The results of the retrospective investigation show in cats transient hyperglycemia occurs more often (3.2%) than permanent hyperglycemia (0.57%). Contrary to overt diabetes mellitus there is no sex- or age-related predisposition. Glucose values above 300 mg/dl (16.65 mmol/l) with maximal values up to 620 mg/dl (34.42 mmol/l) were estimated in 12% of the animals. In 12 from 19 hyperglycemic animals the basal IRI values were between 4 and 14 microU/ml, 11 animals had a lowered I/G ratio. In the following order of frequency the primary diseases found in combination with transient hyperglycemia were: dys- and stranguria, viral and bacterial infections, gastrointestinal diseases, neoplasia, renal insufficiency, cardiopathies etc. With improvement of the underlying disturbance the stress-related hyperglycemia normalized without insulin therapy within a few days. In conclusion, it is necessary to initially identify basic diseases that may trigger the onset of stress-hyperglycemia in the cat. Neither the extent of the glucose level nor a single plasma-insulin-value are valid indicators of confirming the diagnosis of diabetes mellitus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Epidermotropic lymphosarcoma (mycosis fungoides) in a dog].

The clinical findings in a 16-year-old dog with mycosis fungoides are described. The definitive diagnosis was based on the characteristic histopathological lesions in the skin and mucosal biopsies. An immunohistological examination using monoclonal antibodies directed against the Thy-1 antigen of canine peripheral T lymphocytes did not give any further evidence of the identity of the infiltrating lymphoid cells.

Animals↗
PubMed1989

Mechanisms of the angiotensin II effects on the exploratory behavior of rats in open field. II. Interaction of angiotensin II with yohimbine.

The effects of the octapeptide angiotensin II (AT II) and its interaction with yohimbine, an alpha 2-adrenoceptor antagonist, on the exploratory behavior of male rats in open field were studied. AT II (0.1 and 0.5 microgram intracerebroventricularly, i.c.v) increased the open field behavior, mainly ambulation and rearing. Yohimbine (1 and 3 mg/kg) significantly reduced the stimulatory effects of AT II, mainly on ambulation. It is suggested that the augmented release of noradrenaline (NA) resulting from alpha 2-adrenoceptor blockade decreases the exploratory behavior effects of AT II. An interaction between AT II receptors and NA-ergic neurotransmission in the brain might be taken into consideration as an explanation of the influence of yohimbine on AT II effects in open field behavior.

Angiotensin II↗
PubMed1989

Interactions of angiotensin II with piracetam in exploratory behavior and convulsive-seizure threshold.

The interactions between angiotensin II (AT II) and piracetam in exploratory behavior of rats in open field and in pentylenetetrazol (PTZ) convulsive-seizure threshold in mice were studied. AT II at a dose of 0.5 microgram injected intracerebroventricularly (i.c.v.) increased exploratory behavior. Piracetam at a dose of 600 mg.kg-1 administered orally twice daily for 7 days increased the frequency of the exploratory behavior components. AT II decreased this effect of piracetam. AT II (0.5 microgram i.c.v.) tended to increase the PTZ convulsive-seizure threshold. On single administration piracetam had no effect on the convulsive-seizure threshold but on multiple administration it increased the threshold. The two drugs applied together increased the PTZ convulsive-seizure threshold to a larger extent as compared to the effect they exerted when administered alone. The changes in exploratory behavior and in convulsive-seizure threshold, increased by the combination of AT II and piracetam, are explained by the interactions between the two drugs at the level of AT II and GABA binding sites in brain.

Angiotensin II↗