Operationalizing a fisheries social-ecological system through a Bayesian belief network reveals hotspots for its adaptive capacity in the southern North sea.

Fisheries social-ecological systems (SES) in the North Sea region confront multifaceted challenges stemming from environmental changes, offshore wind farm expansion, and marine protected area establishment. In this paper, we demonstrate the utility of a Bayesian Belief Network (BN) approach in comprehensively capturing and assessing the intricate spatial dynamics within the German plaice-related fisheries SES. The BN integrates ecological, economic, and socio-cultural factors to generate high-resolution maps of profitability and adaptive capacity potential (ACP) as prospective management targets. Our analysis of future scenarios, delineating changes in spatial constraints, economics, and socio-cultural aspects, identifies factors that will exert significant influence on this fisheries SES in the near future. These include the loss of fishing grounds due to the installation of offshore wind farms and marine protected areas, as well as reduced plaice landings due to climate change. The identified ACP hotspots hold the potential to guide the development of localized management strategies and sustainable planning efforts by highlighting the consequences of management decisions. Our findings emphasize the need to consider detailed spatial dynamics of fisheries SES within marine spatial planning (MSP) and illustrate how this information may assist decision-makers and practitioners in area prioritization. We, therefore, propose adopting the concept of fisheries SES within broader integrated management approaches to foster sustainable development of inherently dynamic SES in a rapidly evolving marine environment.

Halo-shaped flowing atmospheric pressure afterglow: a heavenly design for simplified sample introduction and improved ionization in ambient mass spectrometry.

The flowing atmospheric-pressure afterglow (FAPA) is a promising new source for atmospheric-pressure, ambient desorption/ionization mass spectrometry. However, problems exist with reproducible sample introduction into the FAPA source. To overcome this limitation, a new FAPA geometry has been developed in which concentric tubular electrodes are utilized to form a halo-shaped discharge; this geometry has been termed the halo-FAPA or h-FAPA. With this new geometry, it is still possible to achieve direct desorption and ionization from a surface; however, sample introduction through the inner capillary is also possible and improves interaction between the sample material (solution, vapor, or aerosol) and the plasma to promote desorption and ionization. The h-FAPA operates with a helium gas flow of 0.60 L/min outer, 0.30 L/min inner, and applied current of 30 mA at 200 V for 6 W of power. In addition, separation of the discharge proper and sample material prevents perturbations to the plasma. Optical-emission characterization and gas rotational temperatures reveal that the temperature of the discharge is not significantly affected (<3% change at 450 K) by water vapor during solution-aerosol sample introduction. The primary mass-spectral background species are protonated water clusters, and the primary analyte ions are protonated molecular ions (M + H(+)). Flexibility of the new ambient sampling source is demonstrated by coupling it with a laser ablation unit, a concentric nebulizer, and a droplet-on-demand system for sample introduction. A novel arrangement is also presented in which the central channel of the h-FAPA is used as the inlet to a mass spectrometer.

Structural white matter changes in adolescents and young adults with maple syrup urine disease.

OBJECTIVE: To get insight into the nature of magnetic resonance (MR) white matter abnormalities of patients with classic maple syrup urine disease (MSUD) under diet control. METHODS: Ten patients with classic MSUD and one with a severe MSUD variant (mean age 21.5 ± 5.1 years) on diet and 11 age and sex-matched healthy subjects were enrolled. Apart from standard MR sequences, diffusion weighted images (DWI), diffusion tensor images (DTI), and magnetization transfer images (MT) were obtained and comparatively analyzed for apparent diffusion coefficient (ADC), tensor fractional anisotropy (FA) and MT maps in 11 regions of interest (ROI) within the white matter. RESULTS: In MSUD patients DWI, DTI and FA showed distinct signal changes in the cerebral hemispheres, the dorsal limb of internal capsule, the brain stem and the central cerebellum. Signal intensity was increased in DWI with a reduced ADC and decreased values for FA. MT did not reveal differences between patients and control subjects. CONCLUSION: Signal abnormalities in the white matter of adolescents and young adults under diet control may be interpreted as consequence of structural alterations like dysmyelination. The reduced ADC and FA in the white matter with preserved MT indicate a reduction in fiber tracks.

Drop-on-demand sample introduction system coupled with the flowing atmospheric-pressure afterglow for direct molecular analysis of complex liquid microvolume samples.

One of the fastest developing fields in analytical spectrochemistry in recent years is ambient desorption/ionization mass spectrometry (ADI-MS). This burgeoning interest has been due to the demonstrated advantages of the method: simple mass spectra, little or no sample preparation, and applicability to samples in the solid, liquid, or gaseous state. One such ADI-MS source, the flowing atmospheric-pressure afterglow (FAPA), is capable of direct analysis of solids just by aiming the source at the solid surface and sampling the produced ions into a mass spectrometer. However, direct introduction of significant volumes of liquid samples into this source has not been possible, as solvent loads can quench the afterglow and, thus, the formation of reagent ions. As a result, the analysis of liquid samples is preferably carried out by analyzing dried residues or by desorbing small amounts of liquid samples directly from the liquid surface. In the former case, reproducibility of sample introduction is crucial if quantitative results are desired. In the present study, introduction of liquid samples as very small droplets helps overcome the issues of sample positioning and reduced levels of solvent intake. A recently developed "drop-on-demand" (DOD) aerosol generator is capable of reproducibly producing very small volumes of liquid (∼17 pL). In this paper, the coupling of FAPA-MS and DOD is reported and applications are suggested. Analytes representing different classes of substances were tested and limits of detections were determined. Matrix tolerance was investigated for drugs of abuse and their metabolites by analyzing raw urine samples and quantification without the use of internal standards. Limits of detection below 2 µg/mL, without sample pretreatment, were obtained.

Invasive aspergillosis in pediatric oncology patients: a rare event with poor prognosis--case analysis to plan better targeted prophylactic or therapeutic measurement.

Despite the implementation of new antifungal drugs, invasive aspergillosis (IA) still remains a considerable challenge in pediatric oncology with a severe mortality. Prophylactic and therapeutic measurement have to be evaluated in these rare but poor prognostic patients. Therefore the entire group of patients at risk of developing IA has to be defined before cooperative prospective trials. In a retrospective analysis including all our patients with malignancies we looked for patients with proven/probable IA. Cases of the period from 2003 to 2008 were analyzed in detail.In the period between 2003 to 2008 24 of 755 patients were affected by proven/ probable IA. Compared to former studies incidence increased from 1.3%in 1980 to 3.4% in 2008. AML patients with or without allogeneic/haploidentical stem cell transplantation were at highest risk (24% and 25% respectively, in comparison to 1% in ALL-patients). Survival after 2 years was 50% for patients with AML and IA. In patients with high risk to develop IA the effect of intensified, intravenous antimycotic prophylaxis has to be proven prospectively in a cooperative and randomized setting.

Aicardi-Goutières syndrome with emphasis on sonographic features in infancy.

BACKGROUND: Aicardi-Goutières syndrome (AGS) is a severe familial, mostly autosomal recessive encephalopathy, first described in 1984. The clinical picture and genetic abnormalities are heterogeneous. US findings in AGS have thus far not been systematically described. OBJECTIVE: The purpose of this study was to analyse sonographic features in AGS and to compare them to CT/MRI. MATERIALS AND METHODS: Four male infants with AGS, two brothers, underwent imaging between the ages of 4 weeks and 6 months. RESULTS: Sonographically isolated mineralization of lenticulostriate vessels, dilatation of the lateral ventricles, subependymal cysts, and diffuse and focal hyperechogenicity of the periventricular white matter and basal ganglia, respectively, were the abnormal findings, that may be present even before the development of major neurological symptoms. CONCLUSION: Early cranial US is able to visualize the whole spectrum of cerebral anomalies in AGS: calcifying microangiopathy, white matter disease and unusual subependymal cysts. The imaging pattern is similar to that of congenital viral infection of the central nervous system, which may mislead the genetic counseling.

Cat scratch disease--heterogeneous in clinical presentation: five unusual cases of an infection caused by Bartonella henselae.

BACKGROUND: Cat-scratch disease (CSD) is common in children, however the wide spectrum of the clinical presentation of CSD may lead to delayed diagnosis. An atypical presentation of CSD includes in its differential diagnosis diseases such as tuberculosis, other mycobacterioses, Epstein-Barr-Virus infection (EBV) or malignant disease. Since, in a small number of cases, these diseases may be present concurrently with an active CSD, it is important to consider CSD early in the differential diagnosis and order the appropriate tests. These tests include serology and, where possible, histology including molecular diagnostic methods on tissue specimens. PATIENTS AND METHOD: We performed a case series of five patients treated in our hospital with a clinical diagnosis of cat-scratch disease, confirmed by serology. An analysis of the history and clinical symptoms associated specifically with an atypical presentation of CSD was performed. RESULTS: The clinical presentation of CSD no longer encompasses the original typical description from 1950, but rather presents with a wide spectrum of signs and symptoms, including the absence of a documented cat scratch, fever, primary lesions or peripheral lymphadenopathy. Low density lesions in spleen, liver and lymph nodes are typical findings in ultrasound, MRI, or CT. Ignoring CSD as a possibility in investigating possible malignancy or tuberculosis could lead to unnecessary hospitalisation and delay in the proper treatment. CONCLUSION: CSD should also be considered in differential diagnosis of any patient with intraabdominal lymphadenopathy, abdominal pain and fever of unknown origin. A careful history is important, however, often patients with CSD have no history of contact with cats. Therefore in atypical cases of CSD the finding of other clinical symptoms and performance of specific diagnostic tests is important. Our experience suggests that early serological testing for Bartonella henselae should be performed and may avoid invasive diagnostic procedures.

Impulse conduction and gap junctional remodelling by endothelin-1 in cultured neonatal rat ventricular myocytes.

Endothelin-1 (ET-1) is an important contributor to ventricular hypertrophy and failure, which are associated with arrhythmogenesis and sudden death. To elucidate the mechanism(s) underlying the arrhythmogenic effects of ET-1 we tested the hypothesis that long-term (24 hrs) exposure to ET-1 impairs impulse conduction in cultures of neonatal rat ventricular myocytes (NRVM). NRVM were seeded on micro-electrode-arrays (MEAs, Multi Channel Systems, Reutlingen, Germany) and exposed to 50 nM ET-1 for 24 hrs. Hypertrophy was assessed by morphological and molecular methods. Consecutive recordings of paced activation times from the same cultures were conducted at baseline and after 3, 6 and 24 hrs, and activation maps for each time period constructed. Gap junctional Cx43 expression was assessed using Western blot and confocal microscopy of immunofluorescence staining using anti-Cx43 antibodies. ET-1 caused hypertrophy as indicated by a 70% increase in mRNA for atrial natriuretic peptide (P < 0.05), and increased cell areas (P < 0.05) compared to control. ET-1 also caused a time-dependent decrease in conduction velocity that was evident after 3 hrs of exposure to ET-1, and was augmented at 24 hrs, compared to controls (P < 0.01). ET-1 increased total Cx43 protein by approximately 40% (P < 0.05) without affecting non- phosphorylated Cx43 (NP-Cx43) protein expression. Quantitative confocal microscopy showed a approximately 30% decrease in the Cx43 immunofluorescence per field in the ET-1 group (P < 0.05) and a reduced field stain intensity (P < 0.05), compared to controls. ET-1-induced hypertrophy was accompanied by reduction in conduction velocity and gap junctional remodelling. The reduction in conduction velocity may play a role in ET-1 induced susceptibility to arrhythmogenesis.

Fetal MRI of the central nervous system: clinical relevance.

OBJECTIVE: Specific conditions of the mother sometimes reduce the quality of ultrasound. In these cases, fetal magnetic resonance imaging (MRI) can be performed after gestational week (GW) 18. Interpretation of subtle disorders or malformations becomes safe not before GW 23. Clinical development of children with central nervous system (CNS) disorders is not predictable with imaging alone. Statistical evidence and personal experience of the medical team are essential in counseling, but optimized imaging is helpful in being more precise. The value of fetal MRI (fMRI) is evaluated. MATERIALS AND METHODS: Twenty-five pregnant women (30.5 +/- 4.5 years) were investigated by additional fMRI. TECHNIQUE: Breath-hold technique with T2 half-Fourier acquisition single-shot turbo spin-echo and T1 FLASH-2D images in three dimensions with field of view of 350 x 400 mm. All cases have been correlated with postnatal MRI, ultrasound, and clinical follow-up. RESULTS: In all fetuses, diagnostic MRI was performed 3-10 days after ultrasound between GW 22 and 34 (GW 26.1 +/- 3.6). Sedation was not necessary. In eight cases of suspicious ultrasound, fMRI confirmed ultrasound findings. In 13 cases, additional diagnoses or exclusions of suspected findings could be established. Complete revision of diagnosis was realized in four cases. Findings could be confirmed by postnatal MRI in 11 patients. The clinical course was not predictable in cases with ambivalent prognosis. CONCLUSIONS: Prenatal diagnosis of CNS pathologies should result in parental counseling. Sufficient diagnostic information, statistical data, and experience of the involved professionals are essential. These results show that in detecting congenital CNS abnormalities fMRI is superior to ultrasound and should be considered in difficult cases.

Infantile onset neurofibromatosis type 2 presenting with peripheral facial palsy, skin patches, retinal hamartoma and foot drop.

BACKGROUND: Neurofibromatosis type 2 (NF2) has long been regarded as an adult onset disease. However, it is now known that many NF2 patients present clinical signs and symptoms in early childhood. We here report an illustrative case of a male adolescent with an infantile onset clinical symptomatology. PATIENT: A 15-year-old male adolescent presented with a history of congenital peripheral facial palsy, amblyopia, a retinal "membrane", and weakness of the left lower limb. Clinical, electrophysiological, radiological, and molecular studies of the patient are shown. A peripheral axonal neuropathy of the left lower limb was found. Formerly unidentified retinal findings could be diagnosed as combined pigment epithelial, and retinal hamartoma (CPERH). In addition, two café au lait spots and a nodular skin tumour were found. Bilateral vestibular schwannoma finally led to the diagnosis of NF2, which could be genetically confirmed. CONCLUSIONS: NF2 can already become evident in infancy. While in adulthood tinnitus, hearing loss and vestibular symptoms are the classical signs, these are often absent in the paediatric group. Children rather have ocular symptoms, neurological problems such as cranial nerve palsies other than eighth nerve, limb weakness and skin manifestations as early clinical signs.

Intracranial hemorrhage in a female leading to the diagnosis of severe hemophilia A and Turner syndrome.

BACKGROUND: Severe hemophilia A (HA) in females is a very rare phenomenon. Ignoring HA as a possible diagnose can result in fatal complications. PATIENTS: We report a 3-month old girl suffering from severe hemophilia A, presenting with intracranial hemorrhage three weeks after drop down from an infant carrier. Recurrent bleeding after neurosurgery led to the diagnosis of a HA by findings of low levels of factor VIII coagulation activity (F8:C) below 1% and normal levels of factor von Willebrand activity. METHODS: Diagnosis of hemophilia A by one stage clotting test and proof by molecular studies via long - range - PCR. Chromosome analysis in metaphases from peripheral blood lymphocytes. RESULTS: Molecular analysis showed inversion of intron 22 as the result of a maternally inherited, distal, F8 gene inversion and chromosome analyses a 45,X karyotype indicative of Turner syndrome in our patient. Diagnosis was hampered by the female sex and the presence of neither a family history of bleeding disorders nor clinical signs of Turner syndrome. CONCLUSION: Our case shows that, although uncommon in female infants, x-linked genetic bleeding disorders like HA are a possible diagnosis by very different reasons. Rare bleeding disorders, although not expected, might be present and the combined clinical, laboratory and genetic analysis are needed to establish the final diagnosis. Repetitive prolonged aPTT and clinical bleeding signs should lead to further hemostasiological investigations. An algorithm for hemostasiological investigations in case of unexplained clinical bleeding is given.

Diagnostic and therapeutic implications of neurological complications following paediatric haematopoietic stem cell transplantation.

Neurological complications are a relevant cause of morbidity and mortality after haematopoietic stem cell transplantation (SCT). We retrospectively analysed neurological complications of 165 paediatric patients who underwent SCT between 1996 and 2003. In all, 111 (67%) transplantations were allogeneic and 54 (33%) transplantations were autologous. Post-SCT neurological complications were seen in 24% of patients. They were seen in six children after autologous SCT and in 11 and 23 cases after allogeneic-related and -unrelated SCT. Neurological symptoms occurred between day +22 and +912 after transplantation and were classified into two groups. The first group (n=21) offered non-repetitive symptoms lasting less than 24 h without any cerebral imaging and cerebrospinal fluid(CSF) abnormalities. The second group (n=19) was characterized by progressive neurological symptoms, pathological MRI findings and/or abnormal results in CSF. Those with a progressive clinical course resulted from infections (n=10), drug toxicity (n=5), cerebrovascular events (n=2) and the central nervous system (CNS) relapse of the underlying disease (n=2). In particular, cerebral aspergillosis and toxoplasmosis after allogeneic unrelated SCT are a major challenge and are associated with a high mortality. In conclusion, our data suggest that patients presenting with progressive neurological symptoms after SCT require prompt diagnostic procedures and initiation in antimicrobial therapy in case of any findings suggestive of CNS infection.

[Evaluation of malformations of the fetal central nervous system using fetal MRI]. / Das fetale MRT in der pränatalen Beurteilung von ZNS-Störungen.

PURPOSE: Ultrasound as the primary prenatal screening modality is used to detect fetal anomalies. Aim of the study was to prove the additional value of fetal magnetic resonance imaging (MRI). MATERIALS AND METHODS: In 25 pregnant women (age 30.6 +/- 4.8; 24 single and one twin pregnancy) with pathologic findings of the central nervous system detected by obstetric ultrasound, a fetal MRI was performed. All sequences (T2w-HASTE, TRUEFISP, T 1w-FLASH 2D, DWI) were performed using the breath-hold technique. The results were compared to postnatal MRI or ultrasound scan findings and tested for correlation with the clinical course and development of these children. RESULTS: Three to seven days after ultrasound, an MRI of all 26 fetuses without sedation was performed (26.6 +/- 4.0 GW). One healthy twin was not included in this study. MRI confirmed the ultrasonographic diagnosis in 7 cases. Compared to ultrasound, an additional pathology could be detected by MRI in 8 cases. In 10 cases ultrasound diagnosis was overruled by MRI. Prenatal MRI findings were confirmed by postnatal imaging in 18 children. The clinical course was predictable in 8 of 15 cases, depending on the pathology detected. Three newborns died in the perinatal period. CONCLUSION: Our results showed that fetal MRI has a high impact as an addition to ultrasound in evaluating congenital CNS pathology. Fetal MRI has become a helpful device for advising parents. However, clinical course and development still cannot be predicted based on MRI findings alone.

In vitro biodegradation testing of Mg-alloy EZK400 and manufacturing of implant prototypes using PM (powder metallurgy) methods.

The study is focussing towards Metal Injection Moulding (MIM) of Mg-alloys for biomedical implant applications. Especially the influence of the sintering processing necessary for the consolidation of the finished part is in focus of this study. In doing so, the chosen high strength EZK400 Mg-alloy powder material was sintered using different sintering support bottom plate materials to evaluate the possibility of iron impurity pick up during sintering. It can be shown that iron pick up took place from the steel bottom plate into the specimen. Despite the fact that a separating boron nitrite (BN) barrier layer was used and the Mg-Fe phase diagram is not predicting any significant solubility to each other. As a result of this study a new bottom plate material not harming the sintering and the biodegradation performance of the as sintered material, namely a carbon plate material, was found.

Monocyte activation in angiogenesis and collateral growth in the rabbit hindlimb.

We have previously shown that monocytes adhere to the vascular wall during collateral vessel growth (arteriogenesis) and capillary sprouting (angiogenesis). In this study we investigated the association of monocyte accumulation with both the production of the cytokines-basic fibroblast growth factor (bFGF) and TNF-alpha-and vessel proliferation in the rabbit after femoral artery occlusion. In particular, we studied the effects of an increase in monocyte recruitment by LPS on capillary density as well as collateral and peripheral conductance after 7 d of occlusion. Monocytes accumulated around day 3 in collateral arteries when maximal proliferation was observed, and stained strongly for bFGF and TNF-alpha. In the lower limb where angiogenesis was shown to be predominant, macrophage accumulation was also closely associated with maximal proliferation (around day 7). LPS treatment significantly increased capillary density (424+/-26.1 n/mm2 vs. 312+/-20.7 n/mm2; P < 0.05) and peripheral conductance (109+/-33.8 ml/min/100 mmHg vs. 45+/-6.8 ml/min/100 mmHg; P < 0.05) as compared with untreated animals after 7 d of occlusion. These results indicate that monocyte activation plays a major role in angiogenesis and collateral artery growth.

The delivery of angiogenic factors to the heart by microsphere therapy.

Microspheres offer the possibility of local noninvasive delivery of drugs over an extended period of time. We adsorbed fibroblast growth factor (FGF) to microspheres of precapillary size that were injected via a coronary catheter. We showed that FGF was released from these microspheres and taken up by endothelial cells, which proliferated following translocation of FGF to the nucleus. This method for application of growth factors allows the precise delivery of angiogenic substances to any selected part of the heart or other organs without causing inflammation or ischemia.

[Fetal MRI]. / Fetales MRT.

Ultrasonography is the method of choice for prenatal malformation screening, but it does not always provide sufficient information for correct diagnosis or adequate abnormality evaluation. Fetal MRI is increasingly being used to complete sonographic findings. It was initially used for evaluation of cerebral abnormalities but is increasingly being applied to other fetal areas. In vivo investigation of fetal brain maturation has been enhanced by MRI. An adequate analysis of fetal chest and abdomen can be achieved with fast T2-, T1-weighted and diffusion-weighted imaging (DWI). The advantages include the great field of view and the excellent soft tissue contrast. This allows correct diagnosis of congenital diaphragmatic hernia and evaluation of the consequences on pulmonary growth. Other pulmonary malformations, such as cystic adenomatoid malformation, sequestration and bronchogenic cysts, can also be easily identified. Renal position can be quickly determined using DWI sequences and renal agenesia can be easily diagnosed with only one sequence. Prenatal MRI is virtually as effective as postnatal examination, dispenses with transport of a potentially very ill newborn, and provides logistic advantages. Therefore, prenatal MRI is useful for adequate postnatal treatment of newborns with malformations.

Paraneoplastic limbic encephalitis with SOX1 and PCA2 antibodies and relapsing neurological symptoms in an adolescent with Hodgkin lymphoma.

BACKGROUND: Immune cross-reactivity between malignant and normal tissues causes the rare, so called paraneoplastic syndrome (PS). In approximately 60% of the patients, various onconeural antibodies are detectable in the cerebrospinal fluid (CSF) and are associated with typical tumour entities. METHODS: We report an unusual case of paraneoplastic limbic encephalitis (PLE) in a 17-year-old adolescent with classical Hodgkin lymphoma. RESULTS: He presented with a variety of neurologic and neuropsychiatric symptoms, profound B-symptoms and typical MRI findings including hyperintense lesions with contrast enhancement in the medial temporal lobe and limbic system. Under immunosuppressive therapy and subsequently chemotherapy the neurological situation only temporarily improved and worsened again after interruption of immunosuppression several times. Thus, multiple courses of multidrug immunosuppressive therapy were administered. To date, five years after initial presentation, the young man is able to walk with walking aids and orthoses and is still on oral prednisolone therapy. Analyses of the CSF and serum revealed anti SOX-1 antibodies at initial presentation but PCA-2 antibodies seven months after diagnosis. CONCLUSION: Neurologic and/or neuropsychiatric symptoms combined with typical MRI findings should raise the suspicion of PS and lead to further diagnostics for an underlying tumour even in children.

Tissue-specific patterns of Gap junctions in adult rat atrial and ventricular cardiomyocytes in vivo and in vitro.

To verify the hypothesis that tissue-specific patterns of gap junctions (GJs) are determined by intrinsic factors within myocytes forming different cardiac tissues, we have compared by quantitative transmission electron microscopy (TEM) the structural features of GJs in adult rat atrial myocytes (AMs) and ventricular myocytes (VMs) in vivo with those in developing GJs in cultured AMs and VMs in vitro. Quantitative TEM data revealed a 3-fold increase in the number of developing GJs per intercalated disk in both AMs and VMs from 6 to 15 days in culture. However, at days 12 and 15, the percentage of GJ length per intercalated disk and mean GJ length were 2-fold higher in VMs than in AMS: Measurements of connexin43 GJs by confocal microscopy confirmed TEM data and demonstrated respectively 2- and 4.5-fold greater mean values of GJ length and area in VMs than in AMS: These differences are attributable to the development of large GJs (>3 micrometer) in VMs, closely resembling those observed in VMs in vivo. Although large GJs in cultured VMs comprised approximately 14% of the total number of GJs, their contribution to total GJ length and area constituted >60% and 85%, respectively. In marked contrast, the number of large GJs in AMs both in vitro and in vivo was <1% from the total number of GJS: These data confirm our hypothesis and provide the first evidence that tissue-specific patterns of GJs in AMs and VMs are determined primarily by intrinsic factors within cardiac myocytes and are developmentally regulated.

Reperfusion of ischemic myocardium: ultrastructural and histochemical aspects.

The effects of reperfusion on ischemic myocardium generally depend on the severity of the preceding ischemic injury. Reperfusion of myocardium, irreversibly injured by ischemia, produces further progression of myocardial necrosis that is accompanied by simultaneously occurring stimulation of interstitial cell proliferation resulting in scar formation. Reperfusion of reversibly injured myocardium leads to structural improvement and reorganization. Thus, it may be stated from the ultrastructural part of this study that reperfusion of ischemic myocardium induces 1) slow structural recuperation after reversible injury, and 2) accelerated cellular destruction and symptoms of scar formation after irreversible ischemic injury. We observed that the reduced tissue content of nicotinamide adenine dinucleotide (NAD), rather than reduced dehydrogenase activity, is the basis of histochemical reactions employing tetrazolium salts. Directly measured NAD tissue content in ischemic tissue correlated well with the degree of ultrastructural injury and with macroscopic differential staining. Occlusion of two small coronary arteries in the same heart followed by reperfusion of only one artery (identical occlusion times for both arteries) showed identical infarct sizes for reperfused and nonreperfused myocardium for occlusion times of 3 and 6 hours. When the effects of occlusion times of less than 3 hours are studied with tetrazolium salts, a difficult technical problem arises: during that time, tissue-NAD concentrations have not decreased enough to enable differential staining. Reperfusion leads to washout of NAD, thus producing differential staining; this may be a harmful effect of reperfusion. However, because early reperfusion leads to significant structural and functional recovery and to small infarcts, reperfusion injury is unlikely to occur. Both ultrastructural and histochemical evidence suggest that reperfusion is beneficial for reversibly injured tissue but accelerates the decay of irreversibly injured tissue.