Normal brain in human newborns: apparent diffusion coefficient and diffusion anisotropy measured by using diffusion tensor MR imaging

PURPOSE

To establish quantitative standards for the directionally averaged water apparent diffusion coefficient (D) and quantitative diffusion anisotropy (A sigma) of normal brains in newborns by using diffusion tensor magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Diffusion tensor MR imaging was performed during the first 36 hours of life in 22 newborns (gestational age range, 31-41 weeks). Values of D and A sigma were measured in regions of interest chosen in the cortical gray matter, centrum semiovale, caudate nuclei, lentiform nuclei, thalami, internal capsules, and cerebellar hemispheres.

RESULTS

The D values in the gray and white matter in newborns are considerably higher than those in adults. There is a striking correlation between gestational age and D, with D decreasing as gestational age increases. The A sigma values in the white matter in newborns are lower than those in adults. Values of A sigma show statistically significant correlations with gestational age only in the white matter of the centrum semiovale, in which A sigma values increase sharply near term.

CONCLUSION

The D values primarily reflect overall brain water content. The A sigma values are more sensitive to tissue microstructure (e.g., white matter packing and myelination). The D and A sigma images reveal information and not apparent on T1- and T2-weighted images.

Normal brain maturation during childhood: developmental trends characterized with diffusion-tensor MR imaging

PURPOSE

To characterize the maturational changes in water diffusion within central gray matter nuclei and central white matter pathways of the human brain by using diffusion-tensor magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Retrospective analysis of normal MR examination findings in 153 subjects (age range, 1 day to 11 years) referred for clinical neuroimaging was performed. All studies included diffusion tensor-encoded echo-planar MR imaging. Isotropic diffusion coefficient (D) and diffusion anisotropy (A(sigma)) were measured in the corpus callosum, internal capsule, caudate nucleus, lentiform nucleus, and thalamus.

RESULTS

exhibited biexponential decay with age in gray and white matter regions, except for monoexponential decay in the genu of the corpus callosum. There was a steep nonlinear increase of A(sigma) in white matter tracts that paralleled the time course of the decline in D. In basal ganglia, only a small linear increase in A(sigma) was observed in patients. A(sigma) changes in the thalamus were intermediate between basal ganglia and white matter structures.

CONCLUSION

Changes in magnitude and anisotropy of water diffusion follow stereotypical time courses during brain development that can be empirically described with multiexponential regression models, which suggests that quantitative scalar parameters derived from diffusion-tensor MR imaging may provide clinically useful developmental milestones for brain maturity.

Proton magnetic resonance spectroscopy in patients with glial tumors: a multicenter study

The authors represent a cooperative group of 15 institutions that examined the feasibility of using metabolic features observed in vivo with 1H-magnetic resonance (MR) spectroscopy to characterize brain tumors of the glial type. The institutions provided blinded, centralized MR spectroscopy data processing long with independent central review of MR spectroscopy voxel placement, composition and contamination by brain, histopathological typing using current World Health Organization criteria, and clinical data. Proton 1H-MR spectroscopy was performed using a spin-echo technique to obtain spectra from 8-cc voxels in the tumor and when feasible in the contralateral brain. Eighty-six cases were assessable, 41 of which had contralateral brain spectra. Glial tumors had significantly elevated intensities of choline signals, decreased intensities of creatine signals, and decreased intensities of N-acetylaspartate compared to brain. Choline signal intensities were highest in astrocytomas and anaplastic astrocytomas, and creatine signal intensities were lowest in glioblastomas. However, whether expressed relative to brain or as intratumoral ratios, these metabolic characteristics exhibited large variations within each subtype of glial tumor. The resulting overlaps precluded diagnostic accuracy in the distinction of low-and high-grade tumors. Although the extent of contamination of the 1H-MR spectroscopy voxel by brain had a marked effect on metabolite concentrations and ratios, selection of cases with minimal contamination did not reduce these overlaps. Thus, each type and grade of tumor is a metabolically hetero-geneous group. Lactate occurred infrequently and in all grades. Mobile lipids, on the other hand, occurred in 41% of high-grade tumors with higher mean amounts found in glioblastomas. This result, coupled with the recent demonstration that intratumoral mobile lipids correlate with microscopic tumor cell necrosis, leads to the hypothesis that mobile lipids observed in vivo in 1H-MR spectroscopy may correlate independently with prognosis of individual patients.

Diagnostic testing for acute head injury in children: when are head computed tomography and skull radiographs indicated?

OBJECTIVE

Despite the frequent occurrence of head injury in children, there is no agreement about clinical screening criteria that indicate the need for imaging studies. This study was undertaken to provide information relevant to the choice of imaging modalities in children with acute head trauma.

METHODOLOGY

A prospective cohort of 322 children seeking care consecutively in an urban pediatric emergency department for nontrivial head injury was assembled. Skull radiographs, head computed tomography, and data forms including mechanism of injury, symptoms, and physical findings were completed for each child.

RESULTS

Intracranial injury occurred in 27 children (8%), whereas 50 (16%) had skull fractures. Of those with intracranial injury, 16 (59%) had normal mental status and no focal abnormalities, and 1 of those 16 required surgery for evacuation of an epidural hematoma. Six (38%) of the 16 were younger than 1 year, 5 of whom had scalp contusion or hematoma without other symptoms. Findings not significantly associated with intracranial injury were scalp contusion, laceration, hematoma, abrasion, headache, vomiting, seizure, drowsiness, amnesia, and loss of consciousness for less than 5 minutes. Findings associated with intracranial injury were skull fracture, signs of a basilar skull fracture, loss of consciousness for more than 5 minutes, altered mental status, and focal neurologic abnormality.

CONCLUSIONS

Intracranial injury may occur with few or subtle signs and symptoms, especially in infants younger than 1 year. The relative risk for intracranial injury is increased almost fourfold in the presence of a skull fracture, although the absence of a skull fracture does not rule out intracranial injury. The significance of nonsurgical intracranial injury in neurologically normal children needs further study.

Carotid restenosis: operative and endovascular management

PURPOSE

Surgical management of carotid restenosis (CR) after carotid endarterectomy (CEA) has been associated with a higher perioperative complication rate than that of primary CEA. We recently used carotid angioplasty-stenting (CAS) as an alternative to operative management in patients who had undergone CEA within three years, and we retrospectively compared these results with those of operative management of CR and the overall results of CEA.

METHODS

CEA was performed on 1065 adult patients (58% symptomatic, 42% asymptomatic), 62% of whom were men (n = 660) and 38% of whom were women (n = 405), from 1989 to 1997. Before our initiation of a program of CAS, 16 operative procedures (1.9% of CEAs) were performed for CR in 14 adult patients (7 women and 7 men). During the last 20 months, CAS was used in the management of 17 CRs (16 patients; 9 women and 7 men).

RESULTS

The 30-day stroke morbidity-death rate for all CEAs (n = 1065) was 1.4%; 11 strokes (1. 0%) occurred (4 major strokes with disability and 7 strokes with minor or no disability), and 4 deaths (0.4%) occurred (2 deaths caused by myocardial infarction, 1 caused by intracranial hemorrhage, and 1 caused by stroke). Operative management of CR (n = 16) included patch angioplasty in 12 cases (autologous vein patches in 10 cases and synthetic patches in 2 cases), whereas interposition grafting was used in 4 cases (saphenous vein in 3 instances and synthetic [polytetrafluoroethylene] in one case). No strokes or deaths were observed. One recurrent laryngeal nerve palsy occurred (6.2%). Among the 16 patients undergoing 17 CAS procedures, the technical procedures were accomplished in all patients. No strokes or deaths occurred. No recurrent restenoses (50% or greater) have been identified within or adjacent to the CAS procedures.

CONCLUSION

CR caused by myointimal hyperplasia can be managed by operative techniques or CAS with comparable periprocedural complications. Although long-term follow-up will be required to determine the incidence of recurrent restenosis, CAS may become the preferred procedure in these cases. A randomized clinical trial ultimately will be necessary to determine the role of CAS, as compared with that of operative management.

The significance of calf muscle pump function in venous ulceration

PURPOSE

Patients with clinically evident chronic venous insufficiency were evaluated to relate the degree of insufficiency and calf muscle pump dysfunction to venous ulceration.

METHODS

Sixty-nine limbs in 55 patients with chronic venous insufficiency by Society for Vascular Surgery/International Society for Cardiovascular Surgery Classification were compared in three groups: classes 1 and 2 with no history of ulceration (19 limbs); class 3 with healed ulceration (20 limbs); and class 3 with active ulcers (30 limbs). Air plethysmography measurements of outflow fraction, venous volume, venous filling time, venous filling index, ejection fraction, ejection volume, residual volume fraction, and residual volume were made. In 62 of the 69 limbs, color-flow duplex ultrasonography was used to determine the pattern of reflux.

RESULTS

The outflow fraction was normal in 84%, 75%, and 77% of nonulcerated, healed, and ulcerated limbs. The venous filling index was abnormal in most limbs (nonulcerated 95%, healed 90%, ulcerated 98%) but not significantly different among groups. Differences in calf muscle pump function were significant. Ulcerated limbs had significantly poorer ejection fractions (p = 0.0002) and greater residual volume fractions (p = 0.0006) than nonulcerated or healed limbs. By ultrasonography, deep and superficial vein incompetence was present in most limbs and was not statistically different among groups. Although venous insufficiency was not measurably different among groups, limbs with active venous ulcers had significantly poorer calf muscle pump function than those with healed ulcers or with no history of ulceration.

CONCLUSION

Venous insufficiency is necessary but not sufficient to cause ulceration, and a deficiency of the calf muscle pump is significant to the severity of venous ulceration.

Sterol regulatory element binding protein binds to a cis element in the promoter of the farnesyl diphosphate synthase gene

Sterol-regulated transcription of the gene for rat farnesyl diphosphate (FPP) synthase (geranyl-diphosphate:isopentenyl-diphosphate geranyltranstransferase, EC 2.5.1.10) is dependent in part on the binding of the ubiquitous transcription factor NF-Y to a 6-bp element within the proximal promoter. Current studies identify a second element in this promoter that is also required for sterol-regulated transcription in vivo. Mutation of three nucleotides (CAC) within this element blocks the 8-fold induction of FPP synthase promoter-reporter genes that normally occurs when the transfected cells are incubated in medium deprived of sterols. Gel mobility-shift assays demonstrate that the transcriptionally active 68-kDa fragment of the sterol regulatory element (SRE-1)-binding protein assays (SREBP-1) binds to an oligonucleotide containing the wild-type sequence but not to an oligonucleotide in which the CAC has been mutated. DNase 1 protection pattern (footprint) analysis indicates that SREBP-1 binds to nucleotides that include the CAC. Both the in vivo and in vitro assays are affected by mutagenesis of nucleotides adjacent to the CAC. Coexpression of SREBP with a wild-type FPP synthase promoter-reporter gene in CV-1 cells results in very high levels of reporter activity that is sterol-independent. In contrast, the reporter activity remained low when the promoter contained a mutation in the CAC trinucleotide. We conclude that sterol-regulated transcription of FPP synthase is controlled in part by the interaction of SREBP with a binding site that we have termed SRE-3. Identification of this element may prove useful in the identification of other genes that are both regulated by SREBP and involved in lipid biosynthesis.

No sex-related differences in human corpus callosum based on magnetic resonance imagery

Recent studies have reported sex-related differences in the morphology of the human corpus callosum in cadaver brains. To further investigate these reports, sagittal magnetic resonance image scans from 40 male and 40 female subjects were used to compare callosal morphology. Relative callosal measurements were calculated by morphometric analysis. Significant sex-related differences were not found for callosal areas, maximal callosal width, or callosal curvature. These results indicate the need for further study before claims of sex-related differences can be accepted.

Comparative analysis of the transferrin and lactoferrin binding proteins in the family Neisseriaceae

Intact cells of several bacterial species were tested for their ability to bind human transferrin and lactoferrin by a solid-phase binding assay using horseradish peroxidase conjugated transferrin and lactoferrin. The ability to bind lactoferrin was detected in all isolates of Neisseria and Branhamella catarrhalis but not in isolates of Escherichia coli or Pseudomonas aeruginosa. Transferrin-binding activity was similarly detected in most isolates of Neisseria and Branhamella but not in E. coli or P. aeruginosa. The expression of transferrin- and lactoferrin-binding activity was induced by addition of ethylenediamine di-o-phenylacetic acid and reversed by excess FeCl3, indicating regulation by the level of available iron in the medium. The transferrin receptor was specific for human transferrin and the lactoferrin receptor had a high degree of specificity for human lactoferrin in all species tested. The transferrin- and lactoferrin-binding proteins were identified after affinity isolation using biotinylated human transferrin or lactoferrin and streptavidin-agarose. The lactoferrin-binding protein was identified as a 105-kilodalton protein in all species tested. Affinity isolation with biotinylated transferrin yielded two or more proteins in all species tested. A high molecular mass protein was observed in all isolates, and was of similar size (approximately 98 kilodaltons) in all species of Neisseria but was larger (105 kilodaltons) in B. catarrhalis.

Detection and assignment of proteins encoded by rice black streaked dwarf fijivirus S7, S8, S9 and S10

The proteins encoded by rice black streaked dwarf fijivirus (RBSDV) genomic segments 7-10 (S7-S10) were characterized. Open reading frames (ORFs) from these segments were expressed as fusion proteins in Escherichia coli. Antibodies raised against the expressed products were used as probes to determine whether the viral ORFs encode structural proteins. In Western blots, antibodies to the expressed S8 and S10 products reacted with a core capsid (65 kDa) and a major outer capsid (56 kDa) protein, respectively, while none of the antibodies to S7 and S9 products reacted with structural proteins. Antisera to RBSDV S7 ORF1 and S9 ORF1 each detected a single protein of the predicted size in total protein extracts from infected rice plants and viruliferous Laodelphax striatellus. Immunoelectron microscopy revealed that antibodies to RBSDV S7 ORF1 and RBSDV S9 ORF1 reacted with tubular structures and viroplasm, respectively, in sections of both infected maize plants and viruliferous L. striatellus. Antisera to ORF2 of S7 and S9 failed to detect any proteins in the infected tissue using either Western blotting or immuno-electron microscopic techniques.

Computed tomography of the spine and spinal cord

Configurations of 50 normal lumbar canals at each vertebral level were assessed and the dimensions of the canal at these levels measured. The appearances of the contents of the canal and their absorption values were carefully analyzed in the lumbar, cervical, and thoracic regions. Of 75 scans of patients with specific spinal symptoms, 38 showed abnormalities representing 19 pathological entities. The appearances of these lesions on scans are compared with normal scans, and the usefulness of CT scans in assessing lesions of the bone and within the canal is discussed.

Quelling the red menace: haem capture by bacteria

Haem is an important bacterial nutrient. As a prosthetic group of several proteins, haem functions as a cofactor mediating oxygen transport, energy generation, and mixed-function oxidation. In addition, the iron chelated in the porphyrin ring may serve as an iron substrate for growth. However, because of its propensity for oxidizing cellular constituents, haem is always associated with proteins. Therefore, the uptake and transit of haem across bacterial membranes requires the participation of protein escorts. Bacteria have evolved a diverse array of surface-exposed receptors dedicated to binding haem and haem-proteins. Following this selective recognition at the bacterial cell surface, haem is transported across the outer membrane via a TonB-dependent process. The control of receptor expression appears to be multifactorial, probably involving a number of global regulators. A model integrating this information is presented.

The diversity of neurologic events in systemic lupus erythematosus. Prospective clinical and computed tomographic classification of 82 events in 71 patients

To investigate outcome and pathophysiology of central nervous system (CNS) systemic lupus erythematosus (SLE), we prospectively codified all cases of CNS SLE. Eighty-two events occurred in 71 patients. Four events in four patients were due to infection and were excluded. Twelve events occurred in 11 women with positive antinuclear antibody but negative anti-DNA antibody test reactions and no other manifestation of SLE. Of the remaining 66 events (56 patients), 26 events were "isolated" and 40 "complex." Non-CNS SLE was "active" during 47 events and "inactive" during 19 events. "Isolated" CNS events were equally likely in clinically "active" and "inactive" SLE. Patients with active SLE were as likely to have an episodic or remittent course as were patients with inactive SLE. "Complex" events, however, were more likely to have favorable outcome than were "isolated" events. "Isolated" events without focal CT abnormalities, the only component of CNS SLE that can be called diffuse lupus encephalitis, accounted for only 20% of all neurologic events.

Periventricular hyperintensity as seen by magnetic resonance: prevalence and significance

Periventricular hyperintensity was identified using long repetition and echo times in spin-echo magnetic resonance imaging of patients with white-matter disease (e.g., multiple sclerosis) caused by local demyelination and in hydrocephalic patients caused by transependymal migration of spinal fluid. A review of 365 consecutives studies revealed that some degree of periventricular hyperintensity is present in most patients (93.5%) regardless of diagnosis. Mild periventricular hyperintensity was seen in patients with no other evidence of intracranial pathology. Periventricular hyperintensity is a normal finding that should not be considered indicative of either demyelinating disease or hydrocephalus. More extensive and severe periventricular hyperintensity is associated with intracerebral pathology, but the finding often is nonspecific. For example, mild periventricular edema from hydrocephalus is impossible to differentiate from the increased periventricular hyperintensity seen in patients with multiple white-matter lesions. Thus, the pattern of periventricular hyperintensity has proven to be of limited value in the clinical assessment of hydrocephalic patients.

High-resolution venography of the brain using magnetic resonance imaging

The purpose of this study was to evaluate a non-flow related magnetic resonance imaging method to visualize small veins independent of arteries in the human brain. A long TE, high-resolution 3D gradient echo MR acquisition was used to highlight venous information. The method is based on the paramagnetic property of deoxyhemoglobin and the resulting phase difference between veins and brain parenchyma at long echo times. The MR magnitude images were masked with a phase mask filter to enhance small structure visibility. Venous information down to sub-pixel vessel diameters of several hundred microns is visible. Venous data are displayed in an angiographic manner using a minimum intensity projection algorithm. Both superficial veins and deep white matter veins are visible. The method has been successfully applied in volunteers. Preliminary results in patients with cerebral arteriovenous malformations indicate its potential in clinical applications. The proposed method is easy to implement and does not require administration of a contrast agent or application of specially designed rf pulses to highlight the veins. Rather it exploits the intrinsic magnetic properties (BOLD-effect) and the prolonged T2* of venous blood. The method may be of diagnostic potential in the assessment of arteriovenous malformations or other vascular venous lesions.

Flexible fiberoptic bronchoscopy and endobronchial tamponade in the management of massive hemoptysis

Flexible fiberoptic bronchoscopic examination with systematic bronchial lavage was performed in ten patients with massive hemoptysis. Localization of the bleeding to the distal segments of the bronchial tree and endobronchial balloon tamponade were achieved in all cases. The technique is rapid, simple, and effective in controlling life-threatening hemoptysis in patients who are unsuitable for resection due to inadequate pulmonary reserve or other causes.

Dural and carotid cavernous sinus fistulas. Diagnosis, management, and complications

Carotid cavernous sinus fistulas (CCSFs) are a rare entity occurring as a result of head trauma and also spontaneously. The major threat from these fistulas is loss of vision. The authors reviewed 18 cases of direct and dural CCSFs seen over the last 10 years and compared our results with 553 cases treated in the literature. Seventy-one percent of our patients with direct CCSFs had successful balloon embolization. In the literature, successful closure of direct CCSFs has ranged from 58 to 100%. As experience with embolization techniques broadens, morbidity and mortality is reduced. The clinical features, diagnostic procedures, therapeutic options, and complications of treatment of CCSFs are discussed.

Palliative treatments of last resort: choosing the least harmful alternative. University of Pennsylvania Center for Bioethics Assisted Suicide Consensus Panel

Comprehensive palliative care, as exemplified by many state-of-the-art hospice programs, is the standard of care for the dying. Although palliative care is very effective, physicians, nurses, patients, families, and loved ones regularly face clinically, ethically, legally, and morally challenging decisions throughout the dying process. This is especially true when terminally ill patients are ready to die in the face of complex, difficult-to-treat suffering and request assistance from their health care providers. Although physician-assisted suicide has received the most attention as a potential last-resort response, this practice remains illegal in the United States except in Oregon, and even there it is relatively infrequent. More commonly, decisions are made about accelerating opioid therapy for pain, foregoing life-sustaining therapy, voluntarily stopping eating and drinking, and administering terminal sedation in response to unacceptable suffering. The moral distinctions between these practices are critical to some but relatively inconsequential to others. This paper illustrates, through summaries of real clinical cases, how each of these practices might be used in response to patients in particular clinical circumstances, keeping in focus the patient's values as well as those of families, other loved ones, and health care providers. The challenge is to find the least harmful solution to the patient's problem without abandoning patients and their loved ones to unacceptable suffering or to acting in a more deleterious way on their own.

Specificity of the lactoferrin and transferrin receptors in Neisseria gonorrhoeae

Lactoferrin (LF) and transferrin (TF) are postulated to be important physiological sources of iron for Neisseria gonorrhoeae. A dot binding assay involving the use of gonococcal total membranes derived from cells grown in iron-limited conditions demonstrated the presence of separate receptors for LF and TF. The ligand and functional specificities of these receptors were examined in competition-binding and growth experiments. The results indicate that the LF and TF receptors are highly specific for the human protein, suggesting that this property may be partially responsible for conferring the human host specificity of N. gonorrhoeae.

Preliminary study of magnetic resonance imaging characteristics in 8- to 16-year-olds with mania

OBJECTIVE

To examine magnetic resonance imaging (MRI) characteristics in children and adolescents with mania according to DSM-III-R criteria.

METHOD

A convenience sample of consecutively referred 8- to 16-year-old manic (n = 10) and normal (n = 5) subjects were assessed using the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present Episode Version, the Children's Global Assessment Scale, and the Family History-Research Diagnostic Criteria. MRI scans were obtained from unsedated subjects using a 1.5 T MR scanner to acquire T1-weighted coronal and sagittal images and T2-weighted axial images. Images were assessed by blind clinical interpretation, ratings of T2-weighted deep white matter hyperintensities and petalia, and computer-assisted volumetric analysis of ventricular and cerebral volumes.

RESULTS

Eight of 10 manic subjects and all 5 controls completed the scans. Scans of 4 manic subjects and 1 control subject showed ventricular or white matter abnormalities by clinical interpretation. Significant findings were positive correlations between increasing age and both right and left ventricular volumes. Two of the 8 manic subjects and no controls had confluent subcortical hyperintensities.

CONCLUSIONS

MRI brain scanning was feasible in 8- to 16-year-olds. Preliminary findings from clinical interpretations and structured ratings suggest structural differences between young manic and normal subjects. Investigations of larger samples are needed to better characterize the differences.

The plasmacytoma growth inhibitor restrictin-P is an antagonist of interleukin 6 and interleukin 11. Identification as a stroma-derived activin A

A stromal protein, designated restrictin-P, that specifically kills plasma-like cells was purified to homogeneity and shown to be identical with activin A. The specificity to plasma-like cells stemmed from the ability of restrictin-P/activin A to competitively antagonize the proliferation-inducing effects of interleukin (IL) 6 and IL-11. Restrictin-P further interfered with the IL-6-induced secretion of acute phase proteins by HepG2 human hepatoma cells and with the IL-6-mediated differentiation of M1 myeloblasts. A competition binding assay indicated that restrictin-P did not interfere with the binding of IL-6 to its receptor on plasma-like cells, suggesting that it may act by intervening in the signal transduction pathway of the growth factor. Indeed, concomitant addition of restrictin-P and IL-6 to cytokine-deprived B9 hybridoma cells was followed by sustained overexpression of junB gene until cell death occurred, while IL-6 alone caused a transient increase only. This altered response to IL-6 stimulation was accompanied by a moderate increase in STAT protein activation. Thus, in this study, we identified the plasmacytoma growth inhibitor, restrictin-P, as being activin A of stromal origin. It is shown that activin A is an antagonist of IL-6-induced functions and that it modifies the IL-6 signaling pattern.

High-resolution blood oxygen-level dependent MR venography (HRBV): a new technique

Our purpose of this study was to demonstrate the clinical potential and spatial resolution of a new MRI technique: high-resolution blood oxygen-level dependent venography (HRBV), in well-known intracranial vascular lesions, such as cavernous and venous angiomas, and venous sinus thrombosis. HRBV provides unique high-resolution information on veins without administration of contrast medium. The data are independent of conventional findings on MRI and potentially useful in characterising and demonstrating the architecture of vascular lesions of the brain.

Computerized tomography and angiography in subarachnoid haemorrhage

Our study of 100 multiple aneurysm cases show that 66 survivied the initial danger period either with surgery, or by conservative treatment. Of these only one may have died subsequently from bleeding from an incidental aneurysm, during a continuing follow-up period now averaging more than seven years. In a separate series of 75 patients presenting clinically with subarachnoid haemorrhage it was possible to lateralize or approximately localize the site of bleeding by CAT in 56; 31 were from aneurysms and 13 from arteriovenous malformations. In the remaining 19 cases CAT was unhelpful in indicating the site of haemorrhage; 12 had aneurysms; no cause was found in the remainder. CAT was more valuable in localization in the seven days following the haemorrhage (86 per cent) than later (34 per cent). The low risk of bleeding from incidental aneurysms makes us feel that treatment confined to the lesion which is responsible for the subarachnoid haemorrhage is not an unreasonable policy in the large majority of these patients. Detailed angiographic study of the site of haemorrhage is performed, but once this has been achieved, more extensive angiography is not routine, but is determined by the requirements of the surgery directed at the site of haemorrhage.

Airway goblet cell mucin: its structure and regulation of secretion

Mucociliary clearance is a major function of the airway epithelium. This important function depends both on the physicochemical properties of the airway mucus and on the activity of the cilia. The former, in turn, is dependent mainly on the quality and quantity of mucous glycoproteins or mucins, which are produced by two different cell types, namely, goblet cells of the epithelium and mucous cells of the submucosal gland. Neither the structural nor the functional differences of mucins produced by these two cell types are yet known. The availability of primary airway epithelial cell culture systems, however, has made it possible to study the structure and regulation of airway goblet cells to some extent. The epithelial mucins are extremely hydrophobic and are associated with various macromolecules, the quality and quantity of which may also affect the physicochemical properties of the mucus. Secretion of epithelial mucins is stimulated by various factors, including a number of inflammatory agents. The recent progress in mucin molecular biological research will allow us to identify different mucin core proteins produced by those different cell types, and, hopefully, the differential functions of these mucins in health and disease.

Development of porcine oocytes from preovulatory follicles of different sizes after maturation in media supplemented with follicular fluids

The development of porcine oocytes from large (3.1-8.0 mm in diameter) or small (<3.1 mm) follicles was examined after maturation culture in medium containing porcine follicular fluid (pFF). Large follicles yielded larger (256 microm v. 221 microm; P<0.05) cumulus-oocyte complexes and more (22 v. 14%) morphologically normal oocytes than small follicles (Experiment 1). In Experiments 2-4, maturation media supplemented with mixed pFF (10%) from small and large follicles was used. More oocytes from large follicles matured (58% v. 91%), formed pronuclei (81% v. 90%) and developed to the blastocyst stage (2% v. 10%) than oocytes from small follicles. In Experiments 5-7, the effects of pFF collected from either small or large follicles on oocyte development were examined. Regardless of the source of oocytes, large-follicle-derived pFF more significantly enhanced preimplantation development than did small-follicle-derived pFF. The highest rate of blastocyst formation (16%) was found when oocytes from large follicles were cultured in maturation medium containing large-follicle-derived pFF. These results suggest that oocytes from large follicles have greater developmental potential than oocytes from small follicles, and that the origin of pFF, which is added to the maturation media, might be an important factor for improving in vitro development of porcine oocytes.