Ocean planning for species on the move provides substantial benefits and requires few trade-offs

Societies increasingly use multisector ocean planning as a tool to mitigate conflicts over space in the sea, but such plans can be highly sensitive to species redistribution driven by climate change or other factors. A key uncertainty is whether planning ahead for future species redistributions imposes high opportunity costs and sharp trade-offs against current ocean plans. Here, we use more than 10,000 projections for marine animals around North America to test the impact of climate-driven species redistributions on the ability of ocean plans to meet their goals. We show that planning for redistributions can substantially reduce exposure to risks from climate change with little additional area set aside and with few trade-offs against current ocean plan effectiveness. Networks of management areas are a key strategy. While climate change will severely disrupt many human activities, we find a strong benefit to proactively planning for long-term ocean change.

Comparison of lignin deposition in three ectopic lignification mutants

The Arabidopsis thaliana mutants de-etiolated3 (det3), pom-pom1 (pom1) and ectopic lignification1 (eli1) all deposit lignins in cells where these polymers would not normally be found. Comparison of these mutants provides an opportunity to determine if the shared mutant phenotype arose by perturbing a common regulatory mechanism in each of the mutants. The mutants were compared using a combination of genetics, histochemistry, chemical profiling, transcript profiling using both Northern blots and microarrays, and bioinformatics. The subset of cells that ectopically lignified was shared between all three mutants, but clear differences in cell wall chemistry were evident between the mutants. Northern blot analysis of lignin biosynthetic genes over diurnal and circadian cycles revealed that transcript abundance of several key genes was clearly altered in all three mutants. Microarray analysis suggests that changes in the expression of specific members of the R2R3-MYB and Dof transcription factor families may contribute to the ectopic lignification phenotypes. This comparative analysis provides a suite of hypotheses that can be tested to examine the control of lignin biosynthesis.

Light, the circadian clock, and sugar perception in the control of lignin biosynthesis

Experiments were undertaken to investigate some of the mechanisms that may function to regulate lignin biosynthesis (lignification) in Arabidopsis thaliana. Northern blot analyses revealed that several genes encoding enzymes involved in the synthesis of lignin monomers displayed significant changes in transcript abundance over a diurnal cycle. Northern blot analysis also suggested that some of the changes in diurnal transcript abundance were likely to be attributable to circadian regulation, whereas others were likely to be attributable to light perception. Comparison of circadian changes in transcript abundance of lignin biosynthetic genes between wild-type plants and the sex1 mutant, which is impaired in starch turnover, suggested that carbon availability related to starch turnover might determine the capacity to synthesize lignins. This hypothesis was supported by the observation that the sex1 mutant accumulated fewer lignins than wild-type plants. Consistent with the relationship between carbon availability and lignin accumulation, analysis of dark-grown wild-type A. thaliana seedlings uncovered a role for sugars in the regulation of lignin biosynthesis. Analysis of lignin accumulation, as determined by qualitative changes in phloroglucinol staining, suggested that metabolizable sugars positively influence the abundance of lignins. Transcriptome analysis supports the hypothesis that sugars are not merely a source of carbon skeletons for lignification, but they also function as a signal to enhance the capacity to synthesize lignins.

The genetic control of lignin deposition during plant growth and development

Lignins are complex, three-dimensional polymers embedded in the cell walls of specialised plant cells, where they play important roles in plant growth and development. Plants must possess mechanisms to coordinate lignin deposition so that its synthesis occurs at the appropriate time and place, in response to endogenous and exogenous cues. Here we consider the genetic basis of the control of lignin deposition. We focus on the transcriptional regulation of lignification, considering how the genes encoding the lignin biosynthetic pathway might be co-ordinately controlled, and the transcription factors that are likely to be involved. We also discuss the mechanisms regulating lignification that have been revealed by mutants with altered lignin deposition. We conclude that, while transcriptional regulation is a common feature in the control of lignification, there are many different regulators that may bring about this common mode of regulation. Contents Summary 17 I. Introduction 17 II. Transcriptional regulation of genes encoding lignin biosynthetic enzymes 19 III. Co-ordinate regulation of genes encoding lignin biosynthetic enzymes 21 IV. Mutants with altered spatial and temporal control of lignification 23 V. Conclusion 28 Acknowledgements 28 References 28.

Comparison of isotopic and non-isotopic labelling for in situ hybridisation of various mRNA targets with cRNA probes

In situ hybridisation methods to localise messenger ribonucleic acid (mRNA) targets in tissue sections or cell preparations using riboprobes can be successful with either isotopic or non-isotopic labelling. Investigators often wish to decide which labelling method provides the maximum specificity, sensitivity and resolution, with minimum nonspecific background. In this study we compared isotopic (35S) and non-isotopic (digoxigenin) labelling, using a variety of probes and paraffin-embedded tissues. The targets were human beta-actin and von Willebrand Factor mRNAs in archival human tissues; and mRNAs for two closely related trefoil factor family (TFF) peptides, TFF2 and TFF3, in rat duodenum. Patterns of localisation with both isotopic and non-isotopic probes were broadly similar for each target. The 35S labelling provided good contrast and sensitive detection under darkfield illumination, but the cellular or subcellular resolution of the target was less precise than that obtained with the digoxigenin-labelled probes in transmitted light. Digoxigenin labelling in individual cells was more clearly demonstrated, but occasionally the contrast of positive staining with background was poor. The sensitivity of each method appeared to be similar for these high-abundance targets, therefore the choice between isotopic and non-isotopic labels is dependent upon the aim of the study and the cellular resolution required.

A robust method for isotopic riboprobe in situ hybridisation to localise mRNAs in routine pathology specimens

In situ Hybridisation (ISH) to detect mRNA is widely applicable to studies of human pathology and experimental models including transgenic mice, where it can provide crucial information as to where a gene is expressed, that is not available in other ways. ISH was used to establish that relatively high levels of expression of E-cadherin mRNA were associated with long-term survival in colorectal cancer, before suitable antisera became available. There is increasing awareness that ISH can be used to help select between candidate disease genes found at a linked locus, and that ISH can help validate therapeutic targets. For instance, when several closely related receptor genes are expressed in a tissue, it may be possible to determine which combinations are expressed together in a single cell type. These diverse applications demand a robust method that works on a variety of clinical and experimental materials, and is easily interpreted. To date, the ICRF in situ Hybridisation Service has hybridised over 30,000 sections of principally formalin-fixed, paraffin-embedded tissues, with a high success rate. The practicalities of our preferred method are discussed and key steps for quality control highlighted.

Expression of oestrogen receptor and oestrogen-inducible genes pS2 and ERD5 in large bowel mucosa and cancer

Since there is a preponderance of large bowel cancer in males, both in humans and in experimental models, and hormone replacement therapy is protective, a role for sex steroid hormones in the pathogenesis of this neoplasm seems likely. Evidence of functional oestrogen receptor has been looked for in large bowel mucosa and cancer. Expression of oestrogen receptor, and of the oestrogen-inducible receptor-associated genes pS2 and ERD5, was sought. Oestrogen receptor mRNA was detected in cancers and paired normal mucosae in equal amounts. In situ hybridization identified stromal cells above the muscularis mucosae that were positive for oestrogen receptor mRNA. pS2 mRNA was also detected, with a signal intensity significantly higher in normal mucosa compared with cancers, whereas the reverse was seen with ERD5 mRNA levels. pS2 and ERD5 were expressed in epithelium, with the former in a greater amount in distal colon and rectum than proximal colon. Although oestrogen-inducible and receptor-associated genes are expressed in large bowel mucosa, their expression does not correlate with oestrogen receptor.

Diagnostic accuracy of a rural live video telepathology system

Accuracy of diagnoses rendered using a live video telepathology network was assessed for permanent sections of surgical pathology specimens. To determine accuracy, telepathology diagnoses were compared with those obtained by directly viewing the glass slide using a standard microscope. A total of 294 cases were read via both telepathology and glass slide by attending pathologists at a tertiary care medical center. Overall accuracy was defined as exact concordance between diagnoses. Clinically insignificant differences in diagnoses were excluded to determine clinically significant accuracy. For the 285 cases with complete data, the overall accuracy for telepathology was 0.912 (95% confidence interval [CI], 0.872-0.941), whereas the overall accuracy for glass slide readings was 0.968 (95% CI, 0.939-0.985). This difference is statistically significant (p = 0.009). When focusing on clinically significant discrepancies, where the difference in diagnosis might affect therapeutic decisions, the video accuracy was only slightly less than the glass slide accuracy (0.965 [95% CI, 0.934-0.982] vs. 0.982 [95% CI, 0.957-0.994], respectively), but this difference is not statistically significant (p = 0.302). Most of the cases with clinically significant differences involved lesions with inherently high interobserver variation. Certainty of diagnosis did not differ between video and glass slide readings (p = 0.911), but there was an association between certainty of diagnosis and diagnostic accuracy for video (p = 0.003 for clinically significant accuracies). Based on these findings, we recommend when using this telepathology system that only preliminary diagnoses should be given in the following situations: for diagnostic areas with known high interobserver variability; when the consultant has any degree of uncertainty about the presence or absence of the lesion in question; and when there is insufficient experience using telepathology as a diagnostic medium.

hP1.B, a human P-domain peptide homologous with rat intestinal trefoil factor, is expressed also in the ulcer-associated cell lineage and the uterus

The six-cysteine P-domain motif forms the basic repeat unit of a growing family of mucin-associated peptides. A precursor for a human secretory polypeptide has been discovered by molecular cloning and deduced to have a single P-domain, termed hP1.B. The pre-pro-peptide has 67% amino acid identity with rat intestinal trefoil factor. We find, using the techniques of RNA analysis and in situ hybridization, that this P-domain peptide is expressed in the human gastrointestinal tract, where a number of pathological conditions affect its expression, and surprisingly find it is expressed in the uterus also. In the intestine, hP1.B is expressed by goblet cells, but in Crohn disease this peptide is synthesized and secreted additionally by the ulcer-associated cell lineage that is known to secrete two other trefoil peptides, pS2 and spasmolytic polypeptide (hSP). In the stomach, hP1.B mRNA is relatively scarce but is more abundant in foci of intestinal metaplasia and near to ulceration. Mucin-rich epithelial cells in hyperplastic polyps of the colon also express this peptide. The discovery of this P-domain peptide and its expression in association with mucins support the hypothesis that P-domains with mucins may subserve related functions in the maintenance and repair of mucosal function.

Breast carcinoma simulating fibroadenoma or fibrocystic change by fine-needle aspiration. A study of 16 cases

The cytologic features of fine-needle aspiration specimens from 16 breast carcinomas that closely simulated benign lesions were analyzed and compared to smears from fibroadenomas and fibrocystic change. No combination of features was found that accurately separated all benign and malignant cases. Many nuclei with discernible small nucleoli in smears with many single bipolar nuclei indicated a benign lesion, whereas nuclear hyperchromasia indicated a malignant one.

Localization of intestinal trefoil-factor mRNA in rat stomach and intestine by hybridization in situ

A cDNA encoding rat intestinal trefoil factor (rITF) was prepared by reverse transcription and PCR amplification. The sequence obtained was well conserved with that of other trefoil peptides. An antisense riboprobe produced from the clone was used to localize the sites of ITF expression in the rat gastrointestinal tract using hybridization in situ. We found rITF mRNA in goblet cells in the small intestine and colon; a gradient of signal strength greatest near the crypt base was sometimes present. We found no evidence for rITF expression in Brunner's glands, the pancreas, or most regions of the gastric mucosa. Surprisingly, strong signals for rITF mRNA were detected in a region of stomach at the junction of the squamous fore-stomach with the glandular gastric mucosa. This region, which may correspond to the cardiac region, formed part of a larger area of cells staining positive for acid mucins. We hypothesize that concerted expression occurs of particular trefoil peptides with specific mucins, and that this organization reflects a functional relationship between mucins and trefoil peptides.

How the door opened: the peopling of the New World

The timing, pathways, and number of migrations involved in the early peopling of the New World are examined from a variety of perspectives. Ultimately, the occupation of the Western Hemisphere was a direct result of boreal cultural adaptations in the Old World. Here, we discuss (1) the dates of appearance of these boreal cultural adaptations and their relevance to the peopling of America, (2) archeological and linguistic evidence bearing on the earliest peopling of the New World, (3) ecological and linguistic evidence on two alternative routes into the New World, and (4) the assumptions present in various migration models. The relative strengths of opposing hypotheses are analyzed by observing whether different approaches point to the same answers.

Murine cytolytic CD8+ T cell clones generated in a high cloning efficiency, accessory cell-free culture system express a restricted lymphokine profile

To determine whether cytolytic T lymphocyte activity is associated with a particular lymphokine profile, lymphokine synthesis was analyzed in a large panel of primary clones derived from single murine CD8+ lymph node T cells. The clones were generated at high efficiency (60-70%), under conditions that had been optimized for the induction of specific cytolytic activity, by culture with phorbol 12-myristate 13-acetate, ionomycin, IL-2, and IFN-gamma for 6 days and then with IL-2 and IL-6 for a further 2 days. When the clones were restimulated for 24 hr with IL-2 and immobilized antibodies to CD3, CD8, and LFA-1, most secreted IL-3 and IFN-gamma and about a third secreted TNF. Although levels of production of IL-3 and IFN-gamma were positively correlated with each other (r = 0.85) and weakly correlated with cytolytic activity (r = 0.68 and 0.55, respectively). TNF titers were unrelated to any other function measured. None of the clones tested secreted detectable IL-4 or IL-6. Similarly, analysis of several clones for lymphokine mRNA expression following cDNA amplification by the polymerase chain reaction revealed the presence of IL-2, IL-3, IFN-gamma, TNF-alpha, and GM-CSF but not IL-4 or IL-6 transcripts. Cytolytic CD8+ T cell clones generated in this high efficiency, accessory cell-independent cloning system therefore expressed a restricted lymphokine profile characterized by the synthesis of IL-3 and IFN-gamma, with variable production of TNF.

Quantitative analysis of lymphokine expression in vivo and in vitro

Constitutive lymphokine production by cells isolated from mice injected with keyhole limpet haemocyanin (KLH) or from mice undergoing an acute graft vs host reaction (GVHR) was very low, but could be markedly increased by T cell receptor (TCR) ligation. This suggested that in vivo levels of lymphokine production are much lower than those induced by in vitro stimulation. Serum lymphokine titres were consistent with this possibility, and analysis of lymphokine mRNA levels using S1-nuclease protection demonstrated that in vitro-stimulated cells from normal, KLH and GVHR mice all had markedly increased levels of lymphokine transcripts relative to levels found in vivo. A novel method combining limiting dilution analysis with polymerase chain reaction amplification of cDNA was developed that showed that these differences in levels of lymphokine production were due at least in part to differences in the frequencies of lymphokine mRNA-containing cells. Studies of the means by which differential lymphokine production is achieved demonstrated that CD4+, CD8+ and cytotoxic T lymphocyte (CTL) clones all express a common, restricted set of lymphokines in response to a defined in vitro stimulus, but that individual in vivo primed cells can express at least seven distinct patterns of lymphokine production.

The maintenance of lytic specificity during the development of clones of cytotoxic T lymphocytes from single precursor cells

A high-cloning efficiency, filler cell-free limit-dilution culture system for the growth and differentiation of single cytotoxic T lymphocyte precursors (CTLp) was tested for its ability to maintain the lytic specificity of the resultant clones of cytotoxic T lymphocytes (CTL). The system used non-specific stimulation with phorbyl ester and calcium ionophore, maintenance of growth over the first 6 days of culture with interleukin (IL)-2 and interferon-gamma, and maintenance of growth and differentiation over the last 2 days of culture with IL-2 and IL-6. Under these defined conditions around 50% of all CD4- 8+ T cells developed into CTL clones that were specific in their lytic activity. In contrast, a culture system maintained by irradiated filler cells showed non-specific lysis of both YAC-1 type natural killer targets and of P815 type targets, while a culture system maintained by IL-2 and a crude growth factor preparation showed non-specific lysis of natural killer targets but not of P815. The defined lymphokine culture system was suitable for determining the specificity repertoire of primary CTLp. Using this system, the frequency of reactivity with allogenic tumor targets was found to be approximately one CTLp in 30 for several mouse strain/target cell combinations.

Lymphokine requirements for the development of specific cytotoxic T cells from single precursors

A high cloning efficiency, filler cell-free culture system was developed for the growth of single murine cytotoxic T lymphocyte precursors (CTLp) and their differentiation into cytotoxic T lymphocytes (CTL). The system used nonspecific stimulation with phorbol ester and calcium ionophore in the presence of recombinant lymphokines. The optimal lymphokine combination was interleukin 2 throughout, together with interferon-gamma during the first 6 days and interleukin 6 during the last 2 days of culture. Under these conditions half of all CD4-CD8+ T cells became CTL clones. The CTL were CD4-CD8+CD3+ TcR alpha/beta+ and were derived from CD4-CD8+Pgp-1- precursors.

Reduction of metastasis in a murine mammary tumour model by heparin and polyinosinic-polycytidylic acid

A murine mammary tumour model has been used to test the efficacy of a combination of heparin and the interferon inducer, poly I:C on spontaneous metastasis from a s.c. primary tumour and on experimental metastasis following i.v. injection of tumour cells. This treatment has no effect on the growth of primary tumours, but lung metastases arising from these tumours were reduced. When tumour cells were injected i.v. the number of lung colonies was significantly reduced and survival time extended. Short-term treatment did not prevent the subsequent growth of extravasated, but dormant tumour cells, although mice treated for 8 or 12 weeks survived at least 6 months without any sign of lung colonies. Several mechanisms may contribute to the overall effect of this treatment; a reduction in the mitotic indices of lung colonies (observed in poly I:C treated mice) and also NK cells appeared to be important for the effectiveness of poly I:C since the reduction in experimental metastasis was abrogated by concomitant treatment with anti-asialo GM1 serum.

Amplification of the c-erb B-2 oncogene and prognosis of breast adenocarcinoma

Fifty patients with typical infiltrating ductal adenocarcinoma of the breast were studied for amplification of the c-erb B-2 (neu/HER-2) oncogene within the tumor DNA. Amplification, ranging from 4 to greater than 50 copies per cell, was observed in 17 (34%) of the samples. The presence of c-erb B-2 gene amplification was not significantly correlated with patient survival, metastases, recurrence, or overall histologic grade. However, amplification was significantly associated with increased mitotic activity. Also, amplification of c-erb B-2 showed a significantly negative association with both progesterone and estrogen receptor presence. Progesterone receptor presence correlated significantly with survival.

Reinfection of virus free mice with mouse mammary tumour virus

BR6/Icrf mice carrying a milk-transmitted mammary tumour virus (MMTV) develop tumours after several pregnancies. If the mice are freed from MMTV, no tumours develop. In the experiments described in this paper, MMTV was reintroduced into MMTV-free mice by foster nursing, which was least effective if the pups were exposed to the virus only during the first week of life. Exposure for even a short time after that age led to a tumour incidence similar to that found in normally infected mice. Reinfection was also achieved by injection of MMTV-containing milk into weanling or pregnant mice, and was then transmitted naturally to the next generation.

IgD production and other lymphocyte functions in HIV infection: immaturity and activation of B cells at different clinical stages

T and B cell function, in particular IgD production in vitro, were studied across the spectrum of HIV infection in homosexual men and compared with seronegative homosexual and heterosexual male controls. Proliferation to phytohaemagglutinin (PHA) was reduced most strikingly in symptomatic HIV infection; it was also impaired in HIV seronegative homosexual men and there was no difference between these and asymptomatic HIV seropositives or those with persistent generalized lymphadenopathy (PGL). Spontaneous IgG and IgM production were increased in patients with PGL and Kaposi's sarcoma; pokeweed mitogen (PWM)-induced production of IgG and IgM was reduced in all HIV infected subjects. Spontaneous production of IgD was highest in asymptomatic HIV infection, with raised values also seen in PGL and AIDS with opportunist infection; IgD production was suppressed by PWM in the same groups. These data indicate an increase in circulating immature B cells. Markers of B cell immaturity and polyclonal activation are apparent to differing degrees at different stages of HIV infection.

Comparison of metastatic cell lines derived from a murine mammary tumour, and reduction of metastasis by heparin

A murine mammary carcinoma, which had a high potential for metastasis to the lungs, was established in culture, and from the parent line several clonally derived variants were isolated, showing different characteristics including metastatic potential. C1, a high metastatic clone, and C2, a low one, were selected for further study. When tumour cells were injected s.c. the growth rates of the resulting tumours were higher when they developed from the parent line (P2) or C1 cells, than from C2 cells. The numbers of lung colonies seen following i.v. inoculation of tumour cells also varied, C2 cells yielding the lowest score. In vitro C1 cells were more efficient at aggregating platelets than C2, an effect reduced by the addition of heparin. In vivo heparin reduced the number of tumour cells arrested in the lungs after i.v. injection, and also the number lung colonies which subsequently became established. The number of metastases which developed following s.c. injection of tumour cells was also reduced by heparin.

Postendarterectomy heparin-induced thrombocytopenia. Case report

Two episodes of massive bleeding from a sutured arteriotomy were observed within 30 hours after carotid endarterectomy. The patient had received anticoagulation therapy with heparin for 72 hours prior to surgery. A platelet count of 93,000/cu mm was demonstrated following the second hemorrhage. The potential problem of drug-induced thrombocytopenia following vascular surgery is discussed.

Silicone lymphadenopathy in a long distance runner: complication of a silastic prosthesis

A 33-year-old male runner, who had undergone a Swanson silastic prosthetic implant for degenerative joint disease of the first metatarsal head and proximal phalanx of the right great toe, presented with unilateral inguinal lymphadenopathy. Biopsy revealed confluent, non-caseating granulomas containing silastic material. Silicone lymphadenopathy is unusual and most frequently presents as axillary adenopathy in patients with rheumatoid arthritis as a sequelae of prosthetic surgery. This case is clinically distinctive for its site of presentation in a healthy athlete and is histologically remarkable for the marked granulomatous response to the silastic elastomers.

Experience with limited versus extensive disc removal in patients undergoing microsurgical operations for ruptured lumbar discs

Of 68 patients undergoing microsurgical operations for ruptured lumbar discs, 33 were treated by removing only the herniated fragments. In the remaining 35, an attempt was made to remove the entire disc. No recurrences followed the more extensive discectomies during follow-up periods varying from 11 to 30 months. Seven recurrences followed operations in which only the offending fragment was removed (recurrence rate of 21%), four within 6 months. Among 68 patients treated by conventional neurosurgical techniques, there was only one recurrence during follow-up periods of at least 4 years. None of the operations was clearly superior in relieving leg pain, but microsurgically treated patients spent less time in the hospital and returned to work more quickly.

Three-year prospective study of HTLV-III/LAV infection in homosexual men

170 symptom-free homosexual men were recruited in London in 1982-83 and 133 were evaluable in 1983-85. Of the 33 who were seropositive to HTLV-III/LAV at entry, 4 (12%) progressed to AIDS, 16 (48%) progressed to persistent generalised lymphadenopathy (PGL), and 13 (40%) remained symptom-free. A further 15 men seroconverted during the study (7% per annum), of whom 8 progressed to PGL. Serial estimations of T lymphocyte subsets showed progressive reduction in T4 numbers in the seropositive groups, but these indices also varied widely in the seronegative group. Counts of T4 and T8 cells or T4/T8 ratio at entry were not of prognostic value. Seronegative subjects were as likely as seropositives to have abnormal immunological tests. Serial measurement of T lymphocyte subsets seems to be of little prognostic or clinical value in the monitoring of populations infected with the HTLV-III/LAV virus. The strongest association with prognosis was an episode of sexually transmitted disease in the six months before entry to the study. This supports the hypothesis that intercurrent infection may be an important co-factor in the acquisition of HTLV-III/LAV infection, and in subsequent disease progression.

Metastasis and morphology of transplanted BR6 mouse mammary tumours

BR6 mouse mammary tumours were maintained by serial s.c. transplantation into female or castrated male syngeneic hosts. The tumours could be broadly classified according to their structure, and usually remained stable through many passages. Occasionally, sarcomatous changes were seen (64 out of 800 cases). Pulmonary metastases were found in 5 per cent of mice bearing transplants of well-differentiated acinar tumours, in 34 per cent with tumours of the acinar/ductal type, and in 97 per cent with poorly differentiated tumours. There was a similar correlation between lymph node metastases and degree of primary tumour differentiation, the incidences being 0, 0.5 and 22 per cent respectively. Sarcomatous changes were associated with a reduced incidence of metastasis. Local invasion of muscle or peritoneum occurred in 32 per cent of mice with well-differentiated tumours, and in 59 per cent with less differentiated tumours. Selection for increased metastatic potential was not achieved by transplantation of lung nodules to a subcutaneous site.

Acute subdural hematoma and death following lateral cervical spinal puncture. Case report

An acute subdural hematoma dissecting into the posterior cranial fossa and resulting in death is reported. The patient had undergone spinal puncture by the lateral cervical technique prior to development of the hematoma. Autopsy demonstrated that the source of hemorrhage was an anomalous intraspinal vertebral artery.

Metastasis of mammary tumours in mice: relationship with morphology of primary tumour, and reproductive background of host

The lungs of BR6 breeding female mice which had developed spontaneous mammary tumours, were examined histologically for the presence of metastases. Metastatic nodules, or tumour cell emboli within blood vessels, were found in the lungs of 3 out of 42 (7 per cent) mice with pregnancy-dependent tumours, and in 33 out of 117 (28 per cent) mice with pregnancy-independent tumours. In general, primary tumours which were well-differentiated and organized were less likely to metastasize than poorly-differentiated ones, but there was an intermediate range within which the likelihood of metastasis could not be predicted. Analysis of the reproductive histories of the mice did not show any significant correlations between factors which might have influenced the growth and progression of the primary tumour and metastatic potential. However, the sustained presence of a high tumour load was associated with an increased probability of metastasis.

Carotid angioplasty in the management of external carotid artery stenosis associated with an occluded internal carotid artery

The author describes the surgical treatment of 14 patients in whom angiography demonstrated total occlusion of the internal carotid artery (ICA) associated with stenosis at the origin of the ipsilateral external carotid artery (ECA). Each patient underwent ECA endarterectomy followed by an angioplasty to enlarge the ECA outflow tract by incorporating the ICA stump into the proximal ECA. Nine patients subsequently underwent superficial temporal-middle cerebral artery anastomosis. There was no mortality or permanent neurological morbidity. This method of treating ECA stenosis is recommended because it is simple and effective and because it simultaneously eliminates the ICA stump as a potential source of cerebral emboli.

The time of origin and the pattern of survival of neurons in the isthmo-optic nucleus of the chick

The time of origin of the cells in the isthmo-optic nucleus (ION--the nucleus of origin of centrifugal fibers to the avian retina) has been determined in the chick by a variant of the cumulative labeling method, using 3H-thymidine autoradiography. All the neurons of the ION are generated (i.e., pass through their last phase of DNA synthesis) over a 50-hour period between the latter part of the fifth and the seventh days of incubation (stages 28--31 of the Hamburger and Hamilton ['51] series) but the cells come to be assembled within the nucleus along a distinct temporo-spatial gradient. The earliest-formed cells occupy the ventrolateral part of the nucleus while the last neurons to be generated come to lie along its dorsomedial margin. When the nucleus is numerically complete, around the eleventh day of incubation, it contains about 22,000 neurons, but between the thirteenth and seventeenth days (stages 39 through 43) this number is produced by nearly 60% to about 9,500 cells. Following the radical extirpation of the one optic cup or the circumscribed removal of the neural retina early on the third day of incubation, the cell loss in the contralateral ION is greatly accentuated, so that by the eighteenth day of incubation no cells remain in the nucleus. Serial counts of the numbers of cells in the nucleus on the side of the eye (or retinal) removals show that it, too, undergoes additional cell degeneration, so that by the end of the phase of naturally occurring neuronal loss, only about half the normal number of cells persist in these experimental animals.

Studies on the development of the chick optic tectum. IV. An autoradiographic study of the development of retino-tectal connections

The normal pattern of innervation of the optic tectum has been studied autoradiographically in a series of chick embryos which were injected intraocularly with [3-H]proline at intervals between the 6th and 21st days of incubation. From the distribution of the radioactively labeled proteins transported in the rapid phase of axonal flow, it is evident that retinal fibers first enter the tectum late on the 6th day of incubation and then spread across its surface from its rostrolateral aspect to its caudo-dorso-medial pole during the ensuing 6 days. At the 9th day, when the fibers have grown across the surface of the rostral half of the tectum, there is no indication that the terminal portions of the axons have left the stratum opticum to enter the outer layers of the stratum grieseum et fibrosum superficiale. The first suggestion of such an invasion of the stratum grieseum et fibrosum superficiale is found at day 10, when labeled fibers can be seen in this stratum, over a restricted, oval, area near the center of the tectum. Over the course of the next 2 days the region of the stratum grieseum et fibrosum superficiale occupied by retinal fibers expands, more-or-less concentrically, until by day 14 some labeled fibers are seen in the outer part of the stratum, throughout the tectum. Concurrent with the ingrowth of optic nerve fibers the final cytoarchitectonic differentiation of the outer layers of the tectum occurs so that by day 18 the autoradiographs show a pattern of labeling of layers a-f of the stratum griseum et fibrosum superficiale similar to that seen in mature, post-hatched chicks. Since the region of the tectum which is first innervated by retinal fibers corresponds to the projection field of the region around the upper end of the choroid fissure where the first ganglion cells are generated, it would appear that the axons of the first-formed ganglion cells grow over the rostral surface of the tectum before establishing the first retino-tectal synapses near the central portion of the tectum. Subsequently, as the ganglion cell population grows concentrically from around the area centralis, there is a parallel expansion of the region in which retino-tectal synapses are being formed in the tectum.