Exceptional continental record of biotic recovery after the Cretaceous-Paleogene mass extinction.

We report a time-calibrated stratigraphic section in Colorado that contains unusually complete fossils of mammals, reptiles, and plants and elucidates the drivers and tempo of biotic recovery during the poorly known first million years after the Cretaceous-Paleogene mass extinction (KPgE). Within ~100 thousand years (ka) post-KPgE, mammalian taxonomic richness doubled, and maximum mammalian body mass increased to near pre-KPgE levels. A threefold increase in maximum mammalian body mass and dietary niche specialization occurred at ~300 ka post-KPgE, concomitant with increased megafloral standing species richness. The appearance of additional large mammals occurred by ~700 ka post-KPgE, coincident with the first appearance of Leguminosae (the bean family). These concurrent plant and mammal originations and body-mass shifts coincide with warming intervals, suggesting that climate influenced post-KPgE biotic recovery.

Pulmonary anatomy and a case of unilateral aplasia in a common snapping turtle (Chelydra serpentina): developmental perspectives on cryptodiran lungs.

The common snapping turtle (Chelydra serpentina) is a well studied and broadly distributed member of Testudines; however, very little is known concerning developmental anomalies and soft tissue pathologies of turtles and other reptiles. Here, we present an unusual case of unilateral pulmonary aplasia, asymmetrical carapacial kyphosis, and mild scoliosis in a live adult C. serpentina. The detailed three-dimensional (3D) anatomy of the respiratory system in both the pathological and normal adult C. serpentina, and a hatchling are visualized using computed tomography (CT), microCT, and 3D digital anatomical models. In the pathological turtle, the right lung consists of an extrapulmonary bronchus that terminates in a blind stump with no lung present. The left lung is hyperinflated relative to the normal adult, occupying the extra coelomic space facilitated by the unusual mid-carapacial kyphotic bulge. The bronchial tree of the left lung retains the overall bauplan of the normal specimens, with some minor downstream variation in the number of secondary airways. The primary difference between the internal pulmonary structure of the pathological individual and that of a normal adult is a marked increase in the surface area and density of the parenchymal tissue originating from the secondary airways, a 14.3% increase in the surface area to volume ratio. Despite this, the aplasia has not had an impact upon the ability of the turtle to survive; however, it did interfere with aquatic locomotion and buoyancy control under water. This turtle represents a striking example of a non-fatal congenital defect and compensatory visceral hypertrophy.

Endoscopic repair of CSF leaks in the postero-superior wall of the frontal sinus - report of 2 cases.

BACKGROUND: Bony defects extending laterally or superiorly within the posterior wall of the frontal sinus are generally deemed too difficult for endoscopic repair in spite of significant progress in surgical endoscopic techniques. PATIENTS AND METHODS: We describe a technique of endoscopic repair of posttraumatic cerebrospinal fluid (CSF) leak from the postero-superior aspect of the frontal sinus in a 40- and a 29-year-old male. In both cases after careful assessment of the surgical anatomy the sinus was widely opened transnasally (Draf IIB and Draf III approach, respectively). Angled (45 and 70°) optics and malleable, individually profiled instruments were used to fit specific anatomic variations encountered during the procedure. RESULTS: Endoscopic manipulation near the dome of the sinus proved to be very limited in spite of a wide surgical opening. In our cases the site of the leak could be identified and successfully sealed with gentle pressure on the dura mater. The bony defects were repaired with a 2-layer reconstruction technique. There were no signs of recurrence during 6 months follow-up. CONCLUSION: With contemporary endoscopic instrumentation, endoscopic closure of CSF leaks in the supero-posterior wall of the frontal sinus is feasible, especially in patients with favourable anatomy of the frontal sinus.

Endoscopic trans-nasal approach for biopsy of orbital tumours using image-guided neuro-navigation system.

BACKGROUND: Histopathological diagnosis of intraorbital tumours is of crucial value for planning further therapy. The aim of the study was to explore clinical utility of image-guided endoscopy for biopsy of orbital tumours. METHOD: Trans-nasal endoscopic biopsy of intraorbital mass lesions was performed in 6 patients using a neuro-navigation system (Medtronic Stealth Station Treon plus). The CT and MRI 1 mm slice images were fused by the system in order to visualise both bony and soft tissue structures. The anatomic fiducial registration protocol was used during the procedure. RESULTS: All lesions were precisely localised and the biopsies could be taken from the representative part of the pathological mass. None of the patients developed aggravation of ocular symptoms after the procedure. The operative corridor as well as the size of orbital wall fenestration could be limited to a minimum. The accuracy of neuro-navigation remained high and stable during the entire procedure. CONCLUSIONS: The image-guided neuro-navigation system facilitated endoscopic localisation and biopsy of intraorbital tumours and contributed to the reduction of surgical trauma during the procedure. The technique was particularly useful in small, medially located, retrobulbar tumours and in unclear situations when the structure of the lesion resembled surrounding intraorbital tissue.

Atraumatic suction tip for microneurosurgery--clinical experience.

Our two-year experience with a new atraumatic tip for the neurosurgical suction tube is described. During microneurosurgical procedures the tip reduces injury to fragile vital brain structures and protects them from being aspirated into the suction tube. The perforated membrane of the appended suction tip does not impede evacuation of blood in any situation and can be easily cleaned off without demounting. The device can be immediately attached to the tube and disconnected. The neurosurgeon need not concentrate on its use, in contrast to those systems with active suction pressure control. The atraumatic suction tip is available in several sizes to fit different callibers of suction tubes.

Detection and monitoring of cerebral hemodynamic disturbances with transcranial color-coded duplex sonography in patients after head injury.

Reduced cerebral blood flow after severe head injury results in an increased risk of ischemic brain damage. Blood flow should therefore be monitored with a simple, reliable method. Transcranial color-coded Doppler sonography (TCCS) is an accepted tool for the diagnosis of cerebral vasospasm; however, its usefulness in evaluating patients with head injury has not been proven. Cerebral blood-flow velocity in the middle, anterior, and posterior cerebral arteries was measured with a 2.5 MHz probe (Aplio SSA 770A, Toshiba, Japan) in 36 subjects with moderate or severe head injury. Serial measurements of resistance index (RI), peak-systolic, end-diastolic, and mean velocity in the middle cerebral arteries were performed 2-24 h after head trauma and in the subsequent days during hospitalization. Immediately after head trauma, increased RI values, and unusually decreased blood-flow velocity (mainly in MCA) were observed. Microcirculation disturbances were suspected because the end-diastolic velocity had substantially diminished. Changes in blood-flow parameters correlated with the clinical state, and in most cases, a poor prognosis. In some patients, blood-flow velocity increased above the normal reference limit and this implied poor prognosis. Transcranial color-coded Doppler sonography is a reliable, repeatable, and accessible tool that provides information about cerebral blood-flow disturbances and may hold diagnostic and prognostic importance.

Tympanic temperature reflects intracranial temperature changes in humans.

The purpose of the study was to identify extracranial locations in which temperature changes in humans reflect those of intracranial temperature in a reliable and repeatable way. This was achieved by subjecting 14 non-anaesthetized patients after neurosurgery to face fanning while intracranial and extracranial temperatures were continuously measured. In all patients the cranium was closed and the group included both febrile and non-febrile as well as hyperthermic and normothermic patients. The patients' faces were fanned for 20-30 min, with a small fan at an air speed of 3.25 m s(-1). This gave intracranial temperature changes measured in the subdural space ( T(sd)) that were highly and significantly correlated ( r=0.91, P<0.05, n=14) with changes in tympanic temperatures ( T(ty)). A low, statistically insignificant correlation ( r=0.40, P>0.05, n=12) was found between T(sd) and oesophageal temperatures. In conclusion, intracranial temperature changes, induced by face fanning, were reliably reflected by the changes in T(ty).

Human brain temperature in vivo: lack of heating during color transcranial Doppler ultrasonography.

This study was undertaken to assess the effect of ultrasound on human brain temperature in vivo. The investigation consisted of direct recording of intracranial temperature during color transcranial Doppler (TCD) sonography in a neurosurgical patient. The temperature was recorded from 3 thermocouples. One was implanted together with an intracranial pressure sensor into a surgically reduced intraparenchymal hematoma, the second was placed within the subdural space close to the temporal acoustic window, and the third was located extracranially at the outer surface of the temporal bone. Tympanic temperatures were also measured to give an approximation of global brain temperature. A 2.5-MHz transducer was used, and the system settings were as follows: spatial peak temporal average intensity = 234 mW/cm2 in B-mode at a maximum power of 32.3 mW and 2132 mW/cm2 in Doppler mode at a maximum power of 149.3 mW. Neither increase in the intraparenchymal brain temperature nor increase in the temperature at the bone/soft tissue interface was observed during 30 minutes of insonation. The ipsilateral tympanic temperature increased by only 0.06 degree C, and this value may be regarded as a measure of the overall increase in brain temperature. Passive cooling effect produced by the transducer, which was at ambient temperature, was found to reach the brain surface and to surpass any possible heating caused by the ultrasound. The results indicate that no noticeable increases in human brain temperature occur in response to ultrasound emitted by a color TCD device at high transmitter power settings within the diagnostic range.

Structural pluralism and all-cause mortality.

OBJECTIVES: This study tested the hypothesis that "structural pluralism" reduces age-standardized mortality rates. Structural pluralism is defined as the potential for political competition in communities. METHODS: US counties were the units of analysis. Multiple regression techniques were used to test the hypothesis. RESULTS: Structural pluralism is a stronger determinant of lower mortality than any of the other variables examined--specifically, income, education, and medical facilities. CONCLUSIONS: These findings support the case for a new structural variable, pluralism, as a possible cause of lower mortality, and they indirectly support the significance of comparable ecologic dimensions, such as social trust.

The superficial skin temperature of low extremities in patients with sciatica.

In some patients with lumbar disc herniation pain of various character and intensity is observed. Besides the pain a number of patients present burning or cold sensations. The superficial temperature of the lower extremities was evaluated in 39 patients with ischialgia, classified for surgical treatment. The differences of skin temperature, however not statistically significant, between the affected and non-affected limbs were found.

[Brain temperature in patients with central nervous system lesions]. / Temperatura mózgu u chorych operowanych z powodu uszkodzen osrodkowego ukladu nerwowego.

The knowledge of human brain temperature is still very limited. In this report we investigated the relationship between brain and trunk temperature in neurosurgical patients during normothermia and fever. Another problem addressed was that of possible gradients of temperature within the brain. We carried out direct recordings of temperature in 63 operated, neurosurgical patients with a variety of intracranial pathologies. Flexible, teflon-coated thermocouples were placed intracranially during neurosurgical procedures. Oesophageal, rectal and tympanic temperatures were also monitored. An error of up to 1.3 degrees C is to be expected in single cases if brain temperature is deduced from the rectal or oesophageal temperature. Mean differences between brain temperature and core body temperature measured in the rectum or in the oesophagus, were between 0 to 0.3 degree C. Tympanic temperature (Tty) improved the approximation of brain temperature (Tbr) to within the mean difference between Tbr-Tty close to 0 degree C. Nevertheless Tty also differed from Tbr by as much as 1 degree C in single cases. Brain temperature was the highest body temperature measured, either in normothermia or in fever. Temperature gradients were proved to exist between the warmer brain interior and cooler surface, with maximal differences in temperature reaching 0.6 degree C. This temperature gradient tended to increase along with the rise in intracranial pressure and deterioration of the level of consciousness. Our results suggest that conclusions regarding brain temperature drawn on the basis of other core temperatures, may lead to significant errors, and intracranial temperature measurement is desirable in neurosurgical intensive care. Temperature gradients within the brain may exacerbate its biochemical injury during ischaemia and fever--a combination seen frequently in neurosurgical patients. This may be particularly so, since brain temperature in fever is the highest body temperature in a high proportion of these patients.

Intracranial pressure processing with artificial neural networks: classification of signal properties.

Intracranial pressure (ICP) is commonly used by neurosurgeons as a source of valuable information about the current condition of the neurosurgical patient. Nevertheless, despite years of effort, extracting clinically valuable information from the ICP signal is still problematical. Approaches, using current values of ICP, may fail to disclose imminent risk, because unpredictable factors can rapidly change the properties of the signal. An alternative approach is to determine some global characteristics of the signal within a longer time interval and such statistical analyses have been proposed by several authors. A further, rarely considered, problem is assessment of the results obtained from the point of view of their practical utility and/or such classification of the obtained properties of the signal that they correspond to certain clinical states of the patient. While this might be a typical task for discriminant analysis, we approached the analysis using an alternative methodology, that of computational intelligence, implemented in artificial neural networks (ANN). We tested two variants of the ANN algorithms for classification and discrimination of global properties of the ICP signal. In a "dynamic pattern classification" the network was presented with several sections of ICP records together with information from the expert-neurosurgeon, classifying 4 risk groups. In this mode no data pre-processing was carried out, in contrast to our second approach, in which the signal had been pre-processed using published statistical analyses and only these intermediate coefficients were fed into the ANN classifier. The results obtained with both classification methods at their current stage of training were similar and approximated to a 70% rate of judgements consistent with the expert scoring. Nevertheless, the method based on the assessment of global parameters from the ICP record looks more promising, because it leaves the possibility for modification of the set of parameters analysed. The new parameters may include information extracted not only from the ICP signal, but also from other diagnostic modalities, like colour coded Doppler ultrasonography. The ultimate goal of this work is to build up a pseudo-intelligent computer expert system, which would be able to reason from a reduced set of input information, available from a standard monitoring modality, because it had been taught salient links between these data and higher-order data, upon which expert scoring was based.

[Analysis of intracranial pressure signals using artificial neural networks]. / Analiza sygnalu cisnienia wewnatrzczaszkowego za pomoca sztucznych sieci neuronowych.

Intracranial pressure (ICP) is influenced by an array of predictable and unpredictable factors. Statistical modelling of this signal has only limited applicability because of the significant load of stochastic components. We tested the efficiency of an alternative approach, based on the methodology of artificial neural networks (ANNs) in the on-line prediction of future values of ICP and in the classification of signal properties. Satisfactory accuracy of forecasting was achieved with the ANNs for a 3-minute prediction horizon, while the prediction quality with autoregressive models of statistical origin was proved unsatisfactory. The results obtained with the ANNs were further improved when signal pre-processing with wavelet transform was employed. Nevertheless, even with the ANN methodology, no sudden breakdowns in the ICP signal (which in this respect might be compared to a "catastrophe") can be forecast with any practical applicability. We therefore applied two ANN algorithms, oriented at classification and discrimination of the global properties of the ICP signal. The neural network was expected to discriminate those sets of signal properties, which were assumed to correspond to certain clinical conditions of the patient. In a "dynamic pattern classification" the network was presented with several sections of ICP records. This was combined with information about the assignment of a given record to one of four arbitrary classes of danger. In this mode no data pre-processing was carried out, in contrast to our second approach, in which the signal was pre-processed with statistical analyses and only these intermediate coefficients were fed to the ANN classifier. The results obtained with both classification methods at their present stage of training were similar and approximated to a 70% rate of judgements consistent with expert scoring. Nevertheless, the method based on the assessment of global parameters of the ICP record seems more promising, because it leaves the possibility of extending the set of training data by information from other diagnostic modalities. The study aims towards the development of a pseudo-intelligent computer expert system, which has would be taught salient links between data extracted from the ICP signal and higher- order data, which contributed to the expert score. Hence the system would be able to make decisions on the basis of a reduced set of input information, available from a standard monitoring modality.

Direct cooling of the human brain by heat loss from the upper respiratory tract.

This study is the first report on human intracranial temperature in conscious patients during and after an upper respiratory bypass. Temperatures were measured in four subjects subdurally between the frontal lobes and cribriform plate (T(cr)) and on the vault of the skull (T(sd)). Further measurements were taken in the esophagus (T(es)) and on the tympanic membrane. Reinstitution of airflow in the upper respiratory tract under conditions of mild hyperthermia gave a rapid drop in T(cr) of 0.4-0.8 degrees C. In three patients the intracranial temperature at the basal aspect of the frontal lobes fell below T(es). Thus local selective cooling of the brain surface below that of the trunk temperature was shown to occur. Intensive breathing by the patients after extubation for a 3-min period produced a cooling at the site of T(cr) measurement at a rate of up to 0.1 degrees C/min, and this response could be evoked on demand. The results support the view that cooling of the upper airway can directly influence human brain temperature.

[Brain temperature during craniotomy in general anesthesia]. / Temperatura mózgu podczas kraniotomii w znieczuleniu ogólnym.

Mild hypothermia may occur spontaneously or, because of its putative neuroprotective effect, may be induced purposefully during neurosurgical procedures. Though the brain is the organ targeted for the purpose of neuroprotection, little is known about its temperature during general anaesthesia and craniotomy. The purpose of this study was to define the relations between core, skin and brain temperature during craniotomy and to compare two modes of inducing thermal insulation in patients during operative procedures. To achieve this we recorded core: rectal (Tre), oesophageal (Tes) and tympanic (Try) temperature, brain temperature in the subdural space (Tsd), and skin temperature on the thigh (Tfe), forehead (Tfr) and sternum (Tst) in 15 patients undergoing standard procedure for aneurysm clipping. In 13 patients the core temperature decreased, whereas skin temperature increased, after induction of general anaesthesia with isofluran. Nevertheless the mean body temperature remained unchanged, thus supporting the view that the cause of the resultant core hypothermia was heat redistribution between the thermal core and the periphery. Special thermofoil proved to be only as effective as a plain cotton blanket in preventing further heat loss during the later phases of the operation. Brain temperature was found to be the lowest core temperature throughout the procedure. It differed by as much as 0.1-1.2 degrees C from rectal temperature (mean 0.75 +/- 0.41 degree C) and reached the level of mild hypothermia (below 35 degrees C) even in those patients in whom rectal temperature indicated the state of normothermia. Furthermore tympanic and oesophageal temperature was on average 0.5 degree C higher than brain temperature. In conclusion, temperature measurements obtained in standard sites do not reflect brain temperature reliably during craniotomy and general anaesthesia. This indicates that the direct measurement of intracranial temperature is necessary for correct estimation of brain hypothermia.

No specific brain protection against thermal stress in fever.

Knowledge about human brain temperature is still very limited, despite evidence demonstrating the critical influence of mild increases in temperature on the ischaemic brain. It has been suggested that in passive and exercise hyperthermia the brain may be protected against thermal damage by a mechanism of selective brain cooling (SBC). It is said to bring about suppression of the temperature of the brain, rendering it significantly lower than trunk and arterial blood temperature. Yet very little is known about the possible role of this mechanism in fever, a condition fundamentally different from "physiological" hyperthermia, especially when it occurs in brain-damaged patients. In our investigation we retrospectively analysed the results of direct recordings of cerebral temperature within the subdural space (Tsd) and within the brain parenchyma (Tbr-16 cases) in 63 unanaesthetized patients following neurosurgical procedures, including 23 with fever > 38 degrees C. The difference between trunk temperature, measured in the rectum (Tre) or in the oesophagus (Tes), and the intracranial temperature, were calculated in all subjects. A statistically significant reduction of these differences, in step with increasing fever, would be compatible with demonstrating a process of selective brain cooling. The offsets Tre-Tsd, Tre-Tbr, and Tes-Tsd were plotted against Tre over a wide range of body temperature and near zero correlation was found. This finding suggests that brain temperature in fever was not selectively suppressed by any specific thermolytic mechanism and that dissipation of the main bulk of cerebral metabolic heat both in normothermia and in fever depends on heat uptake by arterial blood. The results suggest that the brain in fever can be seriously jeopardized by heat stress and no specific cooling mechanism exists, to reduce it below body temperature in feverish neurosurgical patients. Tbr and/or Tsd remained the highest body temperature in 14 out of the 23 patients during fever.

Sympathoexcitatory response to cyclosporin A and baroreflex resetting.

We postulate that the sympathoexcitatory response associated with the immunosuppressive agent cyclosporin A is due to an upward resetting of the arterial baroreflex. We performed studies in conscious intact and sinoaortic-denervated rabbits instrumented with catheters and renal nerve electrodes. In intact rabbits, cyclosporin A (20 mg/kg i.v., 30 minutes) produced significant increases in renal sympathetic nerve activity (100% to 269 +/- 74%, P < .05) but did not increase mean arterial pressure. In intact rabbits, we determined arterial baroreflex curves relating renal sympathetic nerve activity and heart rate to mean arterial pressure by producing ramp increases (intravenous phenylephrine) and decreases (intravenous nitroprusside) in mean arterial pressure. Cyclosporin A treatment produced a shift of the midrange of the baroreflex control of heart rate (78.0 +/- 4.1 to 84.6 +/- 4.7 mm Hg, P < .05) and renal sympathetic nerve activity (74.6 +/- 3.9 to 87.0 +/- 4.8 mm Hg, P < .05). Vehicle administration produced no effects on arterial baroreflex curves relating renal sympathetic nerve activity and heart rate to mean arterial pressure. Compared with vehicle treatment, cyclosporin A reduced the maximum gain of heart rate (-5.6 +/- 0.6 versus -3.1 +/- 0.8 beats per minute per millimeter of mercury, P < .05) but had no effect on the maximum gain of renal sympathetic nerve activity. In conscious sinoaortic-denervated rabbits, cyclosporin A had no effect on mean arterial pressure (95.7 +/- 7.3 to 91.8 +/- 10.8 mm Hg), renal sympathetic nerve activity (100% to 110 +/- 6%). and heart rate (287 +/- 10 to 279 +/- 8 beats per minute). However, when the same sinoaortic-denervated rabbits were anesthetized with sodium pentobarbital, cyclosporin A (20 mg/kg i.v.) produced increases in renal sympathetic nerve activity (100% to 189 +/- 27%). These data indicate (1) that the sympathoexcitatory response to cyclosporin A depends on baroreceptor afferent input in the conscious state and (2) that this response involves an upward resetting of the arterial baroreflex.

Sympathetic neural mechanisms of cyclosporine-induced hypertension.

The immunosuppressant drug cyclosporine A (CsA) has emerged as an important new cause of hypertension in both organ transplant recipients and patients with autoimmune diseases. Despite the clinical importance of this hypertension, the underlying mechanisms have been enigmatic. This article presents a conceptual framework for understanding the pathophysiologic basis of CsA-induced hypertension and focuses on the hypothesis that a common molecular mechanism is involved in mediating the immunosuppressive and the hypertensive effects of CsA. This mechanism involves the binding of CsA to a newly discovered class of cytoplasmic receptors (termed "immunophilins") not only in T lymphocytes but also in the kidney, vascular smooth muscle, and central nervous system, which are the main target tissues mediating CsA-induced hypertension. Binding of CsA to its receptor leads to inhibition of calcineurin, the Ca2+/calmodulin-dependent protein phosphatase. Evidence is reviewed to support the hypothesis that calcineurin inhibition plays a pivotal role in mediating both CsA-induced immunosuppression and hypertension, the latter being produced at least in part by sympathetic neural activation. The elucidation of novel CsA-sensitive cellular signaling pathways has lead to the search for the ideal immunosuppressant drug, one which retains CsA's immunosuppressive efficacy but without its toxicity.

Central command increases muscle sympathetic nerve activity during intense intermittent isometric exercise in humans.

During sustained isometric exercise, central command has very little effect on muscle sympathetic nerve activity (MSNA). To determine if central command has a greater effect on MSNA during intermittent than during sustained contractions, MSNA was recorded with microelectrodes (peroneal nerve) during intermittent isometric handgrip at 25%, 50%, and 75% maximum voluntary contraction (MVC) in 9 human subjects with paced breathing. Similar experiments were performed in 11 additional subjects before and after partial neuromuscular blockade (intravenous curare) to isolate the influence of central command while minimizing force output and thus muscle afferent feedback. Before curare, handgrip at 25% and 50% MVC had no effect on MSNA, whereas handgrip at 75% MVC synchronized the MSNA to the handgrip such that MSNA was 5.7 +/- 1.3 times higher (mean +/- SEM, P < .001) during the contraction periods than during the relaxation periods. After curare, this synchronization of MSNA persisted without attenuation, even though force output fell to < 25% of the initial MVC. From these observations, we conclude that central command causes synchronization of motor activity and muscle sympathetic activity during intense intermittent isometric exercise.