Correction of coronal suture synostosis using suture and dura mater allografts in rabbits with familial craniosynostosis

OBJECTIVE

Resynostosis following surgical correction of craniosynostosis is a common clinical correlate. Recent studies suggest that the dura mater is necessary to maintain suture patency. It has also been hypothesized that dura mater from synostotic individuals may provide aberrant biochemical signals to the osteogenic fronts of the calvaria, which result in premature suture fusion and subsequent resynostosis following surgery. This study was designed to test this hypothesis by surgically manipulating the coronal suture and dura mater in rabbits with familial craniosynostosis to prevent postsurgical resynostosis.

DESIGN

Craniofacial growth and histomorphometric data were collected from 129 rabbits: 72 normal controls and 57 rabbits with bilateral coronal suture synostosis (15 unoperated on controls; 13 surgical controls; 9 dura mater transplant only; 10 suture transplant only; and 10 suture and dura mater transplant). At 10 days of age, all rabbits had radiopaque amalgam markers placed on either side of the coronal, frontonasal, and anterior lambdoidal sutures. At 25 days of age, 42 synostosed rabbits had a 3 to 5-mm wide coronal suturectomy. Coronal sutures and/or underlying dura mater allografts were harvested from same-aged, wild-type, isohistogenic control rabbits and transplanted onto the dura mater of synostosed host rabbits. Serial radiographs were taken at 10, 25, 42, and 84 days of age, and the suturectomy sites were harvested at 84 days of age in 44 rabbits and serially sectioned for histomorphometric examination.

RESULTS

Results revealed that cranial vault growth was significantly (p < .05) improved following surgical release of the fused coronal suture compared with synostosed rabbits who were not operated on but was still significantly different (p < .05) from that of normal control rabbits. By 84 days of age, significant (p < .05) differences were noted in calvarial suture marker separation, cranial vault shape indices, and cranial base angles between rabbits with and without dura mater allografts, probably as a result of resynostosis of the suturectomy site or suture-only allografts. Qualitative histological examination revealed that at 84 days of age rabbits with suture and dura allografts had patent coronal sutures, suture-only allografts had fused coronal sutures with extensive endosteal hyperostosis, dura mater-only allografts had some new bone in the suturectomy site that resembled rudimentary osteogenic fronts, and suturectomy controls had extensive endosteal bone formation and resynostosis of the suturectomy site. Significantly (p < .05) more bone was found in the suturectomy sites of rabbits without dura mater allografts compared with rabbits with dura mater allografts.

CONCLUSIONS

Results support the initial hypothesis that normal dura mater allografts will maintain suture or suturectomy site patency and allow unrestricted craniofacial growth. However, it is still unclear whether the dura mater from normal rabbits was providing biochemical signals to the transplanted sutures or suturectomy sites or simply acting as a barrier to prevent abnormal biochemical signals from the dura mater of synostosed rabbits from reaching the calvaria. The clinical and therapeutic implications of these procedures are discussed.

Hippocampal dependent learning ability correlates with N-methyl-D-aspartate (NMDA) receptor levels in CA3 neurons of young and aged rats

Hippocampal N-methyl-D-Aspartate (NMDA) receptors mediate mechanisms of cellular plasticity critical for spatial learning in rats. The present study examined the relationship between spatial learning and NMDA receptor expression in discrete neuronal populations, as well as the degree to which putative age-related changes in NMDA receptors are coupled to the effects of normal aging on spatial learning. Young and aged Long-Evans rats were tested in a Morris water maze task that depends on the integrity of the hippocampus. Levels of NR1, the obligatory subunit for a functional NMDA receptor, were subsequently quantified both biochemically by Western blot in whole homogenized hippocampus, and immunocytochemically by using a high-resolution confocal laser scanning microscopy method. The latter approach allowed comprehensive, regional analysis of discrete elements of excitatory hippocampal circuitry. Neither method revealed global changes, nor were there region-specific differences in hippocampal NR1 levels between young and aged animals. However, across all subjects, individual differences in spatial learning ability correlated with NR1 immunofluorescence levels selectively in CA3 neurons of the hippocampus. Parallel confocal microscopic analysis of the GluR2 subunit of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA) receptor failed to reveal reliable differences as a function of age or spatial learning ability. This analysis linking age, performance, and NR1 levels demonstrates that although dendritic NR1 is generally preserved in the aged rat hippocampus, levels of this receptor subunit in selective elements of hippocampal circuitry are linked to spatial learning. These findings suggest that NMDA receptor abundance in CA3 bears a critical relationship to learning mediated by the hippocampus throughout the life span.

The existence of the vomeronasal organ in postnatal chimpanzees and evidence for its homology with that of humans

It is currently thought that New World monkeys, prosimians, and humans are the only primates to possess vomeronasal organs (VNOs) as adults. Recent studies of the human VNO suggest that previous investigations on Old World primates may have missed the VNO. We examined nasal septa from the chimpanzee (Pan troglodytes) grossly and histologically for comparison with nasal septa from humans, Old World monkeys (Macaca fascicularis, M. nemistrina) and prosimian primates (Microcebus murinus, Otolemur garnettii). Grossly, chimpanzees had depressions on the nasal septum similar to fossae reported anterior to the VNO openings in humans. Histologically, chimpanzees and humans had bilateral epithelial tubes which were above the superior margin of the paraseptal cartilages (vomeronasal cartilage homologue). The epithelial tubes had a homogeneous ciliated epithelium. These structures were thus positionally and structurally identical to the human VNO and unlike the well-developed prosimian VNOs which were surrounded by vomeronasal cartilage. Macaques had no structures which resembled the VNO of either the prosimians or humans. The results demonstrate that the VNO is present postnatally in the chimpanzee and is almost identical to the human VNO in its anatomical position and histological structure. This in turn suggests that the reported absence of the VNO in at least some adult Old World primates is artifactual, and that further study may provide evidence for its existence in other species.

In vivo microdialysis assessment of extracellular serotonin and dopamine levels in awake monkeys during sustained fluoxetine administration

Fluoxetine (FLU) rapidly enhances extracellular (EC) serotonin (5-HT) in rodent brain, whereas the antidepressant effects of this drug in humans are typically not observed for 2-3 weeks. Thus, the effects of chronic oral FLU administration on neocortical and hippocampal EC 5-HT, and on caudate EC 5-HT and dopamine (DA), were examined in awake monkeys (Macaca fascicularis) using in vivo microdialysis (10.0 mg/kg; 3, 7, 14, and 21 days). On day 3, 5-HT was significantly increased above baseline levels in hippocampus (HC) and caudate. There was a trend for an increase in neocortex EC 5-HT levels. However, by day 7 5-HT remained significantly elevated only in HC, although 5-HT levels elsewhere had not completely returned to baseline. In contrast, levels of the 5-HT metabolite, 5-HIAA, were significantly reduced in all brain regions at all time points. Caudate DA levels tended to be decreased throughout FLU treatment. Local FLU and K(+) infusion were also used at various times during chronic systemic FLU administration to evaluate changes in functional synaptic regulation. In general, these results, along with the significant decrease in 5-HIAA levels and the tendency for basal EC 5-HT levels to remain modestly elevated only in HC during sustained FLU administration, suggest a reduction in releasable pools of 5-HT. Taken together with the trend for a decrease in caudate EC DA levels, these results do not appear to support the current hypothesis regarding the mechanism of action of SSRI antidepressants-that monoaminergic neurotransmission is progressively augmented during chronic treatment.

Trigonocephaly in rabbits with familial interfrontal suture synostosis: the multiple effects of premature single-suture fusion

Previous studies from our laboratory have characterized the craniofacial morphology and growth patterns of an inbred strain of rabbits with autosomal dominant coronal suture synostosis. A number of rabbit perinates from this colony have been collected sporadically over a 5-year period with premature interfrontal suture synostosis. The present study describes the very early onset of craniofacial dysmorphology of these rabbits and compares them to similar-aged normal control rabbits. A total of 40 perinatal New Zealand White rabbits were used in the present study. Twenty-one comprised the sample with interfrontal suture synostosis and ranged in age from 27 to 38 days postconception (term = 31 days) with a mean age of 33.53 days (+/-2.84 days). Nineteen rabbits served as age-matched, normal controls (mean age = 33.05 days +/-2.79 days). Lateral and dorsoventral radiographs were collected from each rabbit. The radiographs were traced, computer digitized, and 12 craniofacial measurements, angles, and indices were obtained. Mean measures were compared using an unpaired Student's t-test. All synostosed rabbits were stillborn or died shortly after birth. Grossly, these rabbits exhibited extreme frontal bossing, trigonocephaly with sagittal keeling, and midfacial shortening. No somatic anomalies were noted. Radiographically, rabbits with interfrontal suture synostosis had significantly (P < 0.05) narrower bifrontal widths, shorter cranial vault lengths, kyphotic cranial base angles, and different cranial vault indices (shapes) compared to controls. Results reveal severe and early pathological and compensatory cranial vault changes associated with premature interfrontal suture synostosis in this rabbit model. The 100% mortality rate noted in this condition may be related to the inheritance of a lethal genetic mutation or to neural compression from reduced intracranial volume. Results are discussed in light of current pathogenic hypotheses for human infants with premature metopic suture synostosis.

Self-reported oral contraceptive use and peripheral joint laxity

STUDY DESIGN

A masked, single-factor, posttest-only control group design.

OBJECTIVE

To explore the relationship between reported oral contraceptive use and peripheral joint laxity.

BACKGROUND

Studies have found an association between increased ligamentous laxity and changes in serum levels of hormones such as estrogen, progesterone, and relaxin. Two of these hormones, estrogen and progesterone, are present in most oral contraceptives. Oral contraceptive users, therefore, provide a population for studying the effects of these hormones on the degree of ligamentous laxity.

METHODS AND MEASURES

Fifty-five women between the ages of 20 and 25 years participated in this study. Thirty users of oral contraceptives were a test group and 25 nonusers of oral contraceptives were controls. The KT-1000 Arthrometer was used to measure passive anterior translation of the tibia in relation to the femur in both knees. Passive abduction and adduction of the proximal interphalangeal (PIP) joint of the second digit of the nondominant hand and distal interphalangeal (DIP) joint hyperextension of the fifth digit of the nondominant hand were measured using a goniometer. A subjective measurement of passive second PIP joint motion was also assessed and a value of minimum, moderate, or maximum laxity was assigned. Independent sample t tests were performed to compare the measurements of the oral contraceptive user and nonuser groups for each joint. A chi-square test compared the subjective PIP joint data between the 2 groups.

RESULTS

No significant differences in laxity measurements at the knee or hand were found between the 2 groups. Average knee laxity varied between 5.7-7.9 mm of anterior displacement for both groups. Average PIP abduction and adduction varied between 6.5-6.7 degrees for both groups and DIP hyperextension was 28.6-29.9 degrees.

CONCLUSIONS

Results of this study indicate that self-reported oral contraceptive use was not associated with peripheral joint laxity.

Cardioprotection with kappa-opioid receptor stimulation is associated with a slowing of cross-bridge cycling

Opioid and alpha-adrenergic receptor activation protect the heart from ischemic damage. One possible intracellular mechanism to explain this is that an improvement in ATP availability contributes to cardioprotection. We tested this hypothesis by correlating postischemic left ventricular developed pressure (LVDP) and myofibrillar Ca(2+)-dependent actomyosin Mg(2+)-ATPase from isolated rat hearts treated with the kappa-opioid receptor agonist U-50488H (1 microM) or the alpha-adrenergic receptor agonist phenylephrine (10 microM) + propranolol (3 microM). Preischemic treatment with U-50488H or phenylephrine + propranolol improved postischemic LVDP recovery by 25-30% over control hearts. Ca(2+)-dependent actomyosin Mg(2+)-ATPase was found to be 20% lower in both U-50488H- and phenylephrine + propranolol-treated hearts compared with control hearts. The kappa-opioid receptor antagonist nor-binaltorphimine (1 microM) abolished the effects of U-50488H on postischemic LVDP and actomyosin Mg(2+)-ATPase activity. Reduced actomyosin ATP utilization was also suggested in single ventricular myocytes treated with either U-50488H or the protein kinase C activator, phorbol 12-myristate 13-acetate (PMA), because U-50488H and PMA lowered maximum velocity of unloaded shortening by 15-25% in myocytes. U-50488H and phenylephrine + propranolol treatment both resulted in increased phosphorylation of troponin I and C protein. These findings are consistent with the hypothesis that kappa-opioid and alpha-adrenergic receptors decrease actin-myosin cycling rate, leading to a conservation of ATP and cardioprotection during ischemia.

The human vomeronasal organ. Part II: prenatal development

During the 20th century, the human vomeronasal organ (VNO) has been controversial regarding its structure, function, and even identity. Despite reports that provide evidence for its presence throughout prenatal and postnatal ontogeny, some studies and numerous textbooks declare its absence in late fetal and postnatal humans. To that end, the present study was designed to establish firmly whether the human VNO is homologous with that of other mammals and whether it degenerates (partially or completely) or persists throughout prenatal development. Fifty human embryos and fetuses (33 d to 32 wk fertilisation age) and 2 neonates were examined by light microscopy. Four embryonic primates (mouse lemurs) were examined for a comparison of VNO embryogenesis. The presence or absence and structural characteristics of the VNO and supporting tissues are described. The first appearance of the VNO was in the form of bilateral epithelial thickenings of the nasal septum, the vomeronasal primordium. The primordia invaginated between 37 and 43 d of age and formed the tubular VNO. The tubular VNO was located dorsally at a variable distance from, but was always spatially separated from the paraseptal cartilages. The mouse lemurs examined in this study and other reports from the literature indicate that the human VNO resembles that of primates having functional VNOs until just after a tubular VNO is formed. Examination of the VNO and adjacent tissues suggested that the VNO may lose receptor cells and corresponding vomeronasal nerves and become a ciliated, pseudostratified epithelium between approximately 12 and 14 wk of age. Our findings indicate the prenatal human VNO goes through 3 successive stages: early morphogenesis, transformation (of the epithelium), and growth. These observations indicated that (1) all embryonic humans develop a vomeronasal organ which is homologous with the VNOs of other mammals, but which has become displaced and highly variable in relative location during embryogenesis; (2) the human vomeronasal organ does not degenerate prenatally, but very likely loses the functional components of the vomeronasal complex of other mammals; and (3) the remnant of the human VNO persists until birth and beyond.

Screening performance of functional and structural measurements of neural damage in open-angle glaucoma: a case-control study from the Baltimore Eye Survey

PURPOSE

To compare the sensitivity and specificity of four approaches to glaucoma screening.

METHODS

Case patients were persons with possible, probable, or definite glaucomatous optic nerve damage, as judged by a glaucoma specialist using Humphrey 24-2 threshold findings and clinical assessment of disc and nerve fiber layer, identified in the population-based Baltimore Eye Survey Follow-up Study. Control patients were participants in the same study, frequency-matched for age, without evidence of glaucomatous optic nerve damage. Participants underwent optic disc photography (Topcon ImageNet), disc imaging (GlaucomaScope), scanning laser polarimetry (Nerve Fiber Analyzer), and suprathreshold field testing (Dicon).

RESULTS

A total of 100 case patients with open-angle glaucoma and 149 control patients were included. Objective imaging had the best screening performance. For the GlaucomaScope, a criterion of cup-to-disc ratio of -0.68 had a sensitivity of 72% and specificity of 82% for detecting eyes with definite or probable glaucomatous optic nerve damage. For the nerve fiber layer, a criterion of The Number as > or = 20 had a sensitivity of 69% and specificity of 77% for detecting eyes with definite or probable glaucomatous optic nerve damage. Usable data could be obtained in 93% of participants with the Dicon and the Nerve Fiber Analyzer and in 82% and 87% of participants with the GlaucomaScope and Topcon instruments, respectively.

CONCLUSIONS

Vertical cup-to-disc ratio, as measured by the GlaucomaScope or Topcon instruments, and the Nerve Fiber Layer neural network Number had the best combination of sensitivity and specificity among the instruments tested. The Nerve Fiber Analyzer had the highest percentage of participants with usable data.

Circuit-specific alterations in hippocampal synaptophysin immunoreactivity predict spatial learning impairment in aged rats

The present study examined the long-standing concept that changes in hippocampal circuitry contribute to age-related learning impairment. Individual differences in spatial learning were documented in young and aged Long-Evans rats by using a hippocampal-dependent version of the Morris water maze. Postmortem analysis used a confocal laser-scanning microscopy method to quantify changes in immunofluorescence staining for the presynaptic vesicle glycoprotein, synaptophysin (SYN), in the principal relays of hippocampal circuitry. Comparisons based on chronological age alone failed to reveal a reliable difference in the intensity of SYN staining in any region that was examined. In contrast, aged subjects with spatial learning deficits displayed significant reductions in SYN immunoreactivity in CA3 lacunosum-moleculare (LM) relative to either young controls or age-matched rats with preserved learning. SYN intensity values for the latter groups were indistinguishable. In addition, individual differences in spatial learning capacity among the aged rats correlated with levels of SYN staining selectively in three regions: outer and middle portions of the dentate gyrus molecular layer and CA3-LM. The cross-sectional area of SYN labeling, by comparison, was not reliably affected in relation cognitive status. These findings are the first to demonstrate that a circuit-specific pattern of variability in the connectional organization of the hippocampus is coupled to individual differences in the cognitive outcome of normal aging. The regional specificity of these effects suggests that a decline in the fidelity of input to the hippocampus from the entorhinal cortex may play a critical role.

Comparative morphology and histochemistry of glands associated with the vomeronasal organ in humans, mouse lemurs, and voles

The vomeronasal organ (VNO) is a chemosensory structure of the vertebrate nasal septum that has been recently shown to exist in nearly all adult humans. Although its link to reproductive behaviors has been shown in some primates, its functionality in humans is still debated. Some authors have suggested that the human VNO has the capacity to detect pheromones, while others described it as little more than a glandular pit. However, no studies have utilized histochemical techniques that would reveal whether the human VNO functions as a generalized gland duct or a specialized chemosensory organ. Nasal septal tissue from 13 humans (2-86 years old) were compared to that of two adult lemurs (Microcebus murinus) and eight adult voles (four Microtus pennsylvanicus and four Microtus ochrogaster). Sections at selected intervals of the VNO were stained with periodic acid-Schiff (PAS), alcian blue (AB), AB-PAS, and PAS-hematoxylin procedures. Results revealed typical well-developed VNOs with tubuloacinar glands in Microtus and Microcebus. VNO glands were AB-negative and PAS-positive in voles and mouse lemurs. Homo differed from Microtus and Microcebus in having more branched, AB and PAS-positive glands that emptied into the VNO lumen. Furthermore, the human VNO epithelium had unicellular mucous glands (AB and PAS-positive) and cilia, similar to respiratory epithelia. These results demonstrate unique characteristics of the human VNO which at once differs from glandular ducts (e.g., cilia) and also from the VNOs of mammals possessing demonstrably functional VNO.

Age-related changes in intracranial pressure in rabbits with uncorrected familial coronal suture synostosis

OBJECTIVE

Chronic, elevated intracranial pressure (ICP) in craniosynostotic infants may result in ocular and neurocapsular problems; however, not all infants exhibit elevated ICP. Clinical ICP studies are further confounded by small and heterogeneic samples, multiple-suture involvement, and varying surgical management protocols. The present study was designed to describe longitudinal changes in ICP in a large, homogenous sample of rabbits with uncorrected familial, nonsyndromic coronal suture synostosis.

METHODS

Ninety-one rabbits were divided into four groups: (1) normal rabbits (n = 28), (2) rabbits with delayed-onset coronal suture synostosis (DOCS; n = 25), (3) rabbits with unilateral coronal suture synostosis (UCS; n = 12), and (4) rabbits with bilateral coronal suture synostosis (BCS; n = 26). ICP was measured at 24 and 42 days of age using a Codman epidural microtransducer.

RESULTS

Rabbits with BCS had a significantly (p < .05) higher mean ICP at 25 days of age than rabbits in the other three groups by approximately 146%. However, by 42 days of age, mean ICP in normal control rabbits and rabbits with DOCS was significantly (p < .01) increased compared with their mean ICP values seen at 25 days of age, while mean ICP in BCS rabbits significantly (p < .01) decreased (by 32%) over the same time period. ICP in rabbits with UCS was between that seen in normal control rabbits and rabbits with BCS and did not significantly (p > .05) change over time.

CONCLUSIONS

These findings suggest that the degree of suture involvement may be related to early increases in ICP. Possible multifactorial explanations for intracranial decompression and compensation in the craniosynostotic rabbit model are discussed.

Neutrophil-specific 99mTc-labeled anti-CD15 monoclonal antibody imaging for diagnosis of equivocal appendicitis

We evaluated 99mTc-labeled anti-CD15 immunoglobulin M monoclonal antibody (LeuTech) for diagnosing acute appendicitis in patients with an equivocal clinical presentation. LeuTech avidly binds to circulating and sequestered human polymorphonuclear neutrophils in vivo, eliminating in vitro cell labeling and blood handling.

METHODS

We studied 49 patients to evaluate the safety and efficacy of LeuTech imaging. 99mTc-labeled LeuTech was prepared on site using a lyophilized kit, 99mTc-labeled pertechnetate, and 2 different incubation techniques, 1 at room temperature and the other at 37 degrees C. The abdomen was serially imaged for up to 3 h after the intravenous administration of 370-740 MBq 99mTc-labeled LeuTech. Scans were read as positive or negative for acute appendicitis or other intraabdominal infection. The institutional diagnosis was established by surgery, other diagnostic studies, or 1-mo clinical follow-up.

RESULTS

Scans were positive for appendicitis in all 26 patients with appendicitis, for a sensitivity of 100%, and negative for appendicitis in 19 of 23 patients without appendicitis, for a specificity of 83%. Accuracy, positive predictive value, and negative predictive value were 92%, 87%, and 100%, respectively. Results were not different between the LeuTech preparations. The rate of laparotomies with negative findings in patients who underwent surgery was 10%. The average time from injection to LeuTech visualization in the appendix for cases positive for appendicitis was 9 min. No serious adverse reactions occurred.

CONCLUSION

LeuTech imaging is safe, rapid, and sensitive for diagnosis of appendicitis in equivocal cases. The potential advantages of LeuTech over currently available radiopharmaceuticals for infection imaging are ease of preparation, absence of blood handling, excellent image quality, no requirement for SPECT, and rapid diagnostic uptake.

Postnatal presence of paraseptal cartilages in humans: a description of morphology and size

Paraseptal cartilages (PCs) have been the subject of controversy, in that some authors believe them to be absent or rarely present, while others have described them to exist at predictable locations in adult human tissue specimens. This study seeks to determine the presence or absence of PCs in humans and describe their morphology and size. Nasal septal tissue from 19 adults and 1 child were paraffin embedded, coronally sectioned, placed on slides, and stained for microscopic observation. For all specimens, PCs were identified and lengths were calculated. Selected PCs were also digitized in order to calculate volume. Results demonstrated that PCs were present in all 20 tissue specimens and assumed a common morphology. In each, PCs were found to begin as hyaline cartilage lobes that extend projections in a superolateral direction as an anteroposterior course is followed. The projections were found to rotate inferiorly until each PC was found to assume a position that extended below the nasal septum. Length measures in adults ranged from 8,725 to 19,000 microm (x = 14,188.9 microm) and volumes ranged from 7.7 to 24.2 (x = 13.2) x 10(-3) ml. A quantitative comparison to foetal data from a previous study suggests prenatal and/or postnatal growth of PCs. Results from this study support the presence of PCs in adult humans as well as prenatal/postnatal growth of PCs.

Brain growth rates in craniosynostotic rabbits

OBJECTIVE

It has been suggested that abnormal brain morphology or growth rates may be a primary causal factor of craniosynostosis due, in part, to a lack of normal growth stretch and tension at the sutural margins. The purpose of the present study was to quantify cerebral hemisphere morphology and growth in a rabbit model of nonsyndromic coronal suture synostosis to determine whether cerebral dysmorphology is primary or secondary to synostosis in this model.

DESIGN

Fifty-seven brains (114 hemispheres) were examined from 40 normal control rabbits and 17 rabbits with bilateral coronal suture synostosis ranging in age from 25 to 450 days postconception (synostosis occurs at approximately 23 days postconception in this model). The calvariae were removed, the brains were fixed in 10% paraformaldehyde, and in situ bilateral measurements of cerebral hemisphere length and cerebral hemisphere width were obtained using a Wild microscope with a camera lucida attachment and digital caliper. Regression analysis was used to compare cerebral cortex growth rates by age between the two groups.

RESULTS

Cerebral hemisphere width and cerebral index regression line slopes had similar y intercepts (23 day postconception) with significantly (p < .05) diverging slopes over time. Normal rabbits increased more rapidly than synostosed rabbits. No significant (p > .05) differences were noted in regression line slopes between groups for cerebral hemisphere length by age or length by width.

CONCLUSIONS

Cerebral dysmorphologies are probably a compensatory, secondary (postsynostotic) event and not a primary causal factor of craniosynostosis in this rabbit model of human familial, nonsyndromic coronal suture synostosis.

Three-dimensional analysis of craniofacial form in a familial rabbit model of nonsyndromic coronal suture synostosis using Euclidean distance matrix analysis

OBJECTIVE

Simple craniosynostoses produce predictable morphologies of the cranial vault, with growth deficits in a direction parallel to the synostosed suture and compensatory growth at sutures that are perpendicular to and attached to the synostosed one. In coronal suture synostosis, anteroposterior growth is inhibited, with compensatory growth in a transverse direction. Information on growth patterns and influence on other craniofacial regions are not as clear. This study tested the hypotheses that (1), both juvenile and adult rabbits with familial, nonsyndromic coronal suture synostosis exhibit significant size and shape differences of the entire craniofacial region relative to normal rabbits as a result of altered growth patterns and that (2), shape differences of the calvaria will precede those of the basicranium.

DESIGN

Fifty anatomic landmarks were located on 94 New Zealand white rabbit crania. The crania were divided into a juvenile, six-week-old age category (n = 53) and an adult, 18-week-old category (n = 41) in order to assess shape differences at different ages. Each age category was sorted into three groups based on growth at the coronal suture: normal sutural growth, delayed onset synostosis, and complete synostosis. Landmarks were digitized in three-dimensions, and statistical analyses on shape differences were carried out using Euclidean distance matrix analysis (EDMA).

RESULTS AND CONCLUSIONS

Results showed that delayed onset synostosis did not produce craniofacial morphology that was different from normal at any age. However, complete synostosis yielded predictable and global craniofacial shape differences at both ages relative to normal skulls, producing an overall shorter, wider cranium with the most markedly compensating regions in a posterosuperior position of the skull. In addition, delayed onset synostosed crania showed no shape differences in the basicranium, relative to normal crania, suggesting primacy of the calvaria in this model of coronal synostosis. However, further investigations are necessary to verify primacy of the calvaria in this model.

Positional changes of the frontoparietal ossification centers in perinatal craniosynostotic rabbits

It has been suggested that craniosynostosis is caused by abnormally located ossification centers (i.e., bony tubers) in the developing skull prior to suture formation [Mathijssen et al., 1996, 1997]. The present study was designed to test this hypothesis in a rabbit model of human familial, nonsyndromic coronal suture (CS) synostosis. Calvariae were taken from 99 New Zealand White rabbit perinates (55 normal controls, 15 with delayed-onset CS synostosis, and 29 with bilateral or unilateral CS synostosis), ranging in age from 23 to 34 days postconception (synostosis occurs at approximately 23 days in this model). Frontoparietal, interfrontal, and interparietal ossification center distances were obtained using a Wild microscope with camera lucida attachment and a 2-D computer digitization technique. Linear regression analysis was used to compare age-related changes in the perinatal ossification centers among groups. Results revealed that frontoparietal ossification center regression line slopes had similar start points (24-day intercepts) with significantly (P < 0.05) diverging slopes over time. Normal and delayed-onset ossification center distance increased more rapidly than in synostosed perinates. No significant (P > 0.05) differences were noted in regression line slopes among groups for interparietal or interfrontal ossification center distances. Results demonstrated that, in synostosed perinates, frontoparietal ossification center location was similar to normals around the time of synostosis and became displaced later. These findings suggest that ossification center (i.e., bony tuber) displacement seen in infants with craniosynostosis is probably a secondary and compensatory, postsynostotic change and not a primary causal factor of synostosis in this rabbit model.

Increased intracranial pressure after coronal suturectomy in craniosynostotic rabbits

It has been suggested that the complications associated with intracranial hypertension in craniosynostotic infants may be managed with surgical release of the synostosed sutures. However, both postoperative increases and decreases in intracranial pressure (ICP) have been reported in heterogeneous samples of infants with syndromic and nonsyndromic craniosynostoses. The present study was designed to describe longitudinal changes in ICP in a homogeneous sample of rabbits with uncorrected and corrected familial coronal suture synostosis and compare them with age-matched normal control rabbits. Fifty-three rabbits were divided into three groups: normal rabbits (n = 28), rabbits with uncorrected bilateral coronal suture synostosis (n = 9), and rabbits with bilateral coronal suture synostosis with coronal suturectomy at 25 days of age (n = 16). ICP was measured at 25 and 42 days of age using a Codman epidural microtransducer. Results revealed that rabbits with uncorrected craniosynostosis had significantly (P < 0.05) higher ICP at 25 days of age than normal control rabbits by approximately 86%. However, by 42 days of age, ICP in normal rabbits increased by 75%, whereas ICP in rabbits with uncorrected craniosynostosis decreased by 69% over the same time. Synostotic rabbits with coronal suturectomy showed a 50% decrease in ICP immediately after surgical release and then followed the normal, age-related ICP pattern, which significantly increased by 75% at 42 days of age. Results suggest that, in the rabbit model, the postsuturectomy rise in ICP may simply be normal, age-related changes, although a longer follow-up will be needed to determine the recurrence of pathological ICP. Possible multifactorial explanations for intracranial decompression and compensation in the craniosynostotic rabbit model are also discussed.

Coronal suture response to distraction osteogenesis in rabbits with delayed-onset craniosynostosis

Recent studies have identified a subpopulation of persons with craniosynostosis who exhibit progressive or delayed-onset synostosis and mild cranial vault deformities. These persons may be good candidates for nonextirpation distraction osteogenesis. The present studies were designed to determine force-displacement parameters and assess the effects of distraction osteogenesis on coronal suture growth and morphologic characteristics in a rabbit model with congenital, delayed-onset craniosynostosis. Data were collected from a total of 178 rabbits: 71 normal controls; 16 normal controls with distraction; 72 with delayed-onset coronal suture synostosis; and 19 with delayed-onset coronal suture synostosis and distraction. At 10 days of age, all rabbits had amalgam markers placed on both sides of the coronal suture. In the force-displacement study, force-displacement distractors were placed across the coronal suture and distracted acutely for 1.0 mm at 42 days of age. Force-displacement curves for the coronal suture were best described by a third-order polynomial regression equation for both normal and synostosed groups. Significant differences (P < 0.05) were found in the mean force necessary to distract a normal suture 1 mm in distance (13.72 kg) compared with a suture with delayed-onset synostosis (48.39 kg). A significant (P < 0.05) relationship was also found between the extent of synostosis and the distractive force in rabbits with delayed-onset synostosis. In the distraction study, internal distractors were fixed across the coronal suture at 25 days of age and percutaneously and intermittently activated at an average of 0.11 mm/day for 42 days (4.54 mm total). Serial radiographs were taken at 10, 25, 42, and 84 days of age. Results revealed that rabbits with delayed-onset synostosis and distraction had significantly (P < 0.01) more coronal suture growth rates compared with rabbits with delayed-onset synostosis and no distraction. Coronal sutures were harvested at 84 days of age for qualitative histologic examination. Normal, distracted coronal sutures showed widened sutural ligaments and thin, active osteogenic fronts. In contrast, distracted coronal sutures from rabbits with delayed-onset synostosis showed narrowed sutural ligaments, thickened and blunt osteogenic fronts, and increased collagen and bony matrix deposition compared with controls. Results suggest that distraction osteogenesis without corticotomy may be a treatment alternative in persons with progressive, delayed-onset synostosis. However, these preliminary data also suggest that distractive forces may accelerate or stimulate osteogenesis differentially in persons with craniosynostosis, possibly through an underlying genetic disorder of bone and cytokine regulation. These differential osteogenic responses to distraction, if validated clinically, will need to be taken into account when planning distraction rate and rhythm protocols for patients with craniosynostosis.

Relationship between the Wide Range Achievement Test 3 and the Wechsler Individual Achievement Test

The present study examined the relationship between the Wide Range Achievement Test 3 and the Wechsler Individual Achievement Test for a sample of children with learning disabilities in two rural school districts. Data were collected for 87 school children who had been classified as learning disabled and placed in special education resource services. Pearson product-moment correlations between scores on the two measures were significant and moderate to high; however, mean scores were not significantly different on Reading, Spelling, and Arithmetic subtests of the Wide Range Achievement Test 3 compared to those for the basic Reading, Spelling, and Mathematics Reasoning subtests of the Wechsler Individual Achievement Test. Although there were significant mean differences between scores on Reading and Reading Comprehension and on Arithmetic and Numerical Operations, magnitudes were small. It appears that the two tests provide similar results when screening for reading, spelling, and arithmetic.

Internal calvarial bone distraction in rabbits with delayed-onset coronal suture synostosis

Recent studies have identified a subpopulation of craniosynostotic individuals who exhibit progressive or delayed-onset synostosis and mild craniofacial growth abnormalities. These individuals may be good candidates for nonextirpation, distraction osteogenesis therapy. The present study was designed to test this hypothesis by using internal calvarial bone distraction in a rabbit model with familial delayed-onset craniosynostosis. Data were collected from 159 rabbits: 71 normal controls, 72 with delayed-onset coronal suture synostosis, 8 with delayed-onset coronal suture synostosis and coronal suturectomy, and 8 with delayed-onset coronal suture synostosis and distraction. At 10 days of age, all rabbits had amalgam markers placed on both sides of the frontonasal, coronal, and anterior lambdoidal sutures. At 25 days of age, correction was accomplished through either a 5-mm-wide suturectomy or distraction osteogenesis. An internal distraction appliance was fixed to the frontal and parietal bones and percutaneously and intermittently activated at an average of 0.10 mm/day for 42 days (4.11 mm total). Serial radiographs were taken at 10, 25, 42, and 84 days of age. Results revealed that rabbits with delayed-onset synostosis had significantly (p < 0.01) reduced coronal suture growth rates (0.04 mm/day) compared with the other three groups (0.07 mm/day). Rabbits with suturectomy and rabbits with distraction showed similar coronal suture responses. However, from 42 to 84 days of age, rabbits with distraction showed reduced growth at the vault sutures and abnormal growth patterns in cranial vault width, cranial vault shape, and cranial base angulation compared with the other three groups. Results demonstrated that, although the normal coronal suture growth rate was maintained in rabbits with delayed-onset synostosis using intermittent distraction osteogenesis, normal adult craniofacial structure was not achieved. Such anomalous growth was probably a result of altered growth vectors and compressive forces at adjacent sutures during distraction. These findings suggest that distraction osteogenesis without corticotomy may be a treatment alternative in individuals with progressive, delayed-onset synostosis, but that internal appliances that generate low-level, continuous distractive forces should be investigated and developed.

Searching for the vomeronasal organ of adult humans: preliminary findings on location, structure, and size

The adult human vomeronasal organ (VNO) has been the focus of numerous recent investigations, yet its developmental continuity from the human fetal VNO is poorly understood. The present study compared new data on the adult human "VNO" with previous findings on the fetal human VNO. Nasal septa were removed from twelve adult human cadavers and each specimen was histologically sectioned. Coronal sections were stained with hematoxylin-eosin and periodic acid-Schiff-hematoxylin. The sections were examined by light microscopy for the presence of VNOs and the anterior paraseptal cartilages (PC). VNOs were quantified using a computer reconstruction technique to obtain VNO length, volume, and vomeronasal epithelium (VNE) volume. Histologically, VNOs and PCs were identified in eleven specimens. VNOs had ciliated, pseudostratified columnar epithelium with goblet cells. Variations (e.g., multiple communications to the nasal cavity) were observed in several specimens. Quantification was possible for 16 right or left VNOs. Right or left VNOs ranged from 3.5 to 11.8 mm in length, from 1.8 to 33.8 x 10(-4)cc in volume, and from 2.7 to 18.1 x 10(-4)cc in VNE volume. Results indicated that the adult human VNO was similar in VNE morphology, lumen shape, and spatial relationships when compared to human fetal VNOs. By comparison with previous fetal VNO measures, mean VNO length, volume, and VNE volume were larger in adult humans. These results support previous suggestions that postnatal VNO growth occurs. Findings on location and spatial relationships of the adult VNO were similar to those seen in human fetuses, but critical questions remain regarding the ontogeny of the vomeronasal nerves and VNE.