Predicting Leg Forces and Knee Moments Using Inertial Measurement Units: An In Vitro Study

We compared the ability of seven machine learning algorithms to use wearable inertial measurement unit (IMU) data to identify the severe knee loading cycles known to induce microdamage associated with anterior cruciate ligament rupture. Sixteen cadaveric knee specimens, dissected free of skin and muscle, were mounted in a rig simulating standardized jump landings. One IMU was located above and the other below the knee, the applied three-dimensional action and reaction loads were measured via six-axis load cells, and the three-dimensional knee kinematics were also recorded by a laboratory motion capture system. Machine learning algorithms were used to predict the knee moments and the tibial and femur vertical forces; 13 knees were utilized for training each model, while three were used for testing its accuracy (i.e., normalized root-mean-square error) and reliability (Bland-Altman limits of agreement). The results showed the models predicted force and knee moment values with acceptable levels of error and, although several models exhibited some form of bias, acceptable reliability. Further research will be needed to determine whether these types of models can be modified to attenuate the inevitable in vivo soft tissue motion artifact associated with highly dynamic activities like jump landings.

Relationship Between Lateral Tibial Posterior Slope and Tibiofemoral Kinematics During Simulated Jump Landings in Male Cadaveric Knees

Background

It is not known mechanistically whether a steeper lateral posterior tibial slope (LTS) leads to an increase in anterior tibial translation (ATT) as well as internal tibial rotation (ITR) during a given jump landing.

Hypothesis

A steeper LTS will result in increased ATT and ITR during simulated jump landings when applying knee compression, flexion, and internal tibial torque of increasing severity.

Study Design

Descriptive laboratory study.

Methods

Seven pairs of cadaveric knees were harvested from young male adult donors (mean ± SD; age, 25.71 ± 5.53 years; weight, 71.51 ± 4.81 kg). The LTS of each knee was measured by a blinded observer from 3-T magnetic resonance images. Two sets of 25 impact trials of ∼700 N (1× body weight [BW] ±10%) followed by 2 sets of 25 trials of 1400 N (2× BW ±10%) were applied to a randomly selected knee of each pair. Similarly, on the contralateral knee, 2 sets of 25 impact trials of ∼1800 N (2.5× BW ±10%) followed by 2 sets of 25 trials of ∼2100 N (3× BW ±10%) were applied. Three-dimensional knee kinematics, including ATT and ITR, were measured at 400 Hz using optoelectronic motion capture. Two-factor linear mixed effect models were used to determine the relationship of LTS to ATT and ITR as impact loading increased.

Results

As LTS increased, so did ATT and ITR during increasingly severe landings. LTS had an increasing effect on ATT (coefficient, 0.50; 95% CI, 0.29-0.71) relative to impact force (coefficient, 0.52; 95% CI, 0.50-0.53). ITR was proportional to LTS (coefficient, 1.36; 95% CI, 0.80-1.93) under increasing impact force (coefficient, 0.49; 95% CI, 0.47-0.52). For steeper LTS, the increase in ITR was proportionally greater than the increase in ATT.

Conclusion

In male knee specimens, a steeper LTS significantly increased ATT and ITR during jump landings.

Clinical Relevance

Increases in ITR and ATT during jump landings lead to increased strain on the anterior cruciate ligament and are therefore associated with greater risk of ligament failure.

Fatigue-driven compliance increase and collagen unravelling in mechanically tested anterior cruciate ligament

Approximately 300,000 anterior cruciate ligament (ACL) tears occur annually in the United States, half of which lead to the onset of knee osteoarthritis within 10 years of injury. Repetitive loading is known to result in fatigue damage of both ligament and tendon in the form of collagen unravelling, which can lead to structural failure. However, the relationship between tissue's structural, compositional, and mechanical changes are poorly understood. Herein we show that repetitive submaximal loading of cadaver knees causes an increase in co-localised induction of collagen unravelling and tissue compliance, especially in regions of greater mineralisation at the ACL femoral enthesis. Upon 100 cycles of 4× bodyweight knee loading, the ACL exhibited greater unravelled collagen in highly mineralized regions across varying levels of stiffness domains as compared to unloaded controls. A decrease in the total area of the most rigid domain, and an increase in the total area of the most compliant domain was also found. The results highlight fatigue-driven changes in both protein structure and mechanics in the more mineralized regions of the ACL enthesis, a known site of clinical ACL failure. The results provide a starting point for designing studies to limit ligament overuse injury.

Anterior cruciate ligament microfatigue damage detected by collagen autofluorescence in situ

PURPOSE

Certain types of repetitive sub-maximal knee loading cause microfatigue damage in the human anterior cruciate ligament (ACL) that can accumulate to produce macroscopic tissue failure. However, monitoring the progression of that ACL microfatigue damage as a function of loading cycles has not been reported. To explore the fatigue process, a confocal laser endomicroscope (CLEM) was employed to capture sub-micron resolution fluorescence images of the tissue in situ. The goal of this study was to quantify the in situ changes in ACL autofluorescence (AF) signal intensity and collagen microstructure as a function of the number of loading cycles.

METHODS

Three paired and four single cadaveric knees were subjected to a repeated 4 times bodyweight landing maneuver known to strain the ACL. The paired knees were used to compare the development of ACL microfatigue damage on the loaded knee after 100 consecutive loading cycles, relative to the contralateral unloaded control knee, through second harmonic generation (SHG) and AF imaging using confocal microscopy (CM). The four single knees were used for monitoring progressive ACL microfatigue damage development by AF imaging using CLEM.

RESULTS

The loaded knees from each pair exhibited a statistically significant increase in AF signal intensity and decrease in SHG signal intensity as compared to the contralateral control knees. Additionally, the anisotropy of the collagen fibers in the loaded knees increased as indicated by the reduced coherency coefficient. Two out of the four single knee ACLs failed during fatigue loading, and they exhibited an order of magnitude higher increase in autofluorescence intensity per loading cycle as compared to the intact knees. Of the three regions of the ACL - proximal, midsubstance and distal - the proximal region of ACL fibers exhibited the highest AF intensity change and anisotropy of fibers.

CONCLUSIONS

CLEM can capture changes in ACL AF and collagen microstructures in situ during and after microfatigue damage development. Results suggest a large increase in AF may occur in the final few cycles immediately prior to or at failure, representing a greater plastic deformation of the tissue. This reinforces the argument that existing microfatigue damage can accumulate to induce bulk mechanical failure in ACL injuries. The variation in fiber organization changes in the ACL regions with application of load is consistent with the known differences in loading distribution at the ACL femoral enthesis.

A Comparison of Inertial Measurement Unit and Motion Capture Measurements of Tibiofemoral Kinematics during Simulated Pivot Landings

Injuries are often associated with rapid body segment movements. We compared Certus motion capture and APDM inertial measurement unit (IMU) measurements of tibiofemoral angle and angular velocity changes during simulated pivot landings (i.e., ~70 ms peak) of nine cadaver knees dissected free of skin, subcutaneous fat, and muscle. Data from a total of 852 trials were compared using the Bland-Altman limits of agreement (LoAs): the Certus system was considered the gold standard measure for the angle change measurements, whereas the IMU was considered the gold standard for angular velocity changes. The results show that, although the mean peak IMU knee joint angle changes were slightly underestimated (2.1° for flexion, 0.2° for internal rotation, and 3.0° for valgus), the LoAs were large, ranging from 35.9% to 49.8%. In the case of the angular velocity changes, Certus had acceptable accuracy in the sagittal plane, with LoAs of ±54.9°/s and ±32.5°/s for the tibia and femur. For these rapid motions, we conclude that, even in the absence of soft tissues, the IMUs could not reliably measure these peak 3D knee angle changes; Certus measurements of peak tibiofemoral angular velocity changes depended on both the magnitude of the velocity and the plane of measurement.

Testing a Quaternion Conversion Method to Determine Human Three-Dimensional Tibiofemoral Angles During an In Vitro Simulated Jump Landing

Lower limb joint kinematics have been measured in laboratory settings using fixed camera-based motion capture systems; however, recently inertial measurement units (IMUs) have been developed as an alternative. The purpose of this study was to test a quaternion conversion (QC) method for calculating the three orthogonal knee angles during the high velocities associated with a jump landing using commercially available IMUs. Nine cadaveric knee specimens were instrumented with APDM Opal IMUs to measure knee kinematics in one-legged 3-4× bodyweight simulated jump landings, four of which were used in establishing the parameters (training) for the new method and five for validation (testing). We compared the angles obtained from the QC method to those obtained from a commercially available sensor and algorithm (APDM Opal) with those calculated from an active marker motion capture system. Results showed a significant difference between both IMU methods and the motion capture data in the majority of orthogonal angles (p < 0.01), though the differences between the QC method and Certus system in the testing set for flexion and rotation angles were smaller than the APDM Opal algorithm, indicating an improvement. Additionally, in all three directions, both the limits of agreement and root-mean-square error between the QC method and the motion capture system were smaller than between the commercial algorithm and the motion capture.

An Anterior Cruciate Ligament Failure Mechanism

BACKGROUND

Nearly three-quarters of anterior cruciate ligament (ACL) injuries occur as "noncontact" failures from routine athletic maneuvers. Recent in vitro studies revealed that repetitive strenuous submaximal knee loading known to especially strain the ACL can lead to its fatigue failure, often at the ACL femoral enthesis.

HYPOTHESIS

ACL failure can be caused by accumulated tissue fatigue damage: specifically, chemical and structural evidence of this fatigue process will be found at the femoral enthesis of ACLs from tested cadaveric knees, as well as in ACL explants removed from patients undergoing ACL reconstruction.

STUDY DESIGN

Controlled laboratory study.

METHODS

One knee from each of 7 pairs of adult cadaveric knees were repetitively loaded under 4 times-body weight simulated pivot landings known to strain the ACL submaximally while the contralateral, unloaded knee was used as a comparison. The chemical and structural changes associated with this repetitive loading were characterized at the ACL femoral enthesis at multiple hierarchical collagen levels by employing atomic force microscopy (AFM), AFM-infrared spectroscopy, molecular targeting with a fluorescently labeled collagen hybridizing peptide, and second harmonic imaging microscopy. Explants from ACL femoral entheses from the injured knee of 5 patients with noncontact ACL failure were also characterized via similar methods.

RESULTS

AFM-infrared spectroscopy and collagen hybridizing peptide binding indicate that the characteristic molecular damage was an unraveling of the collagen molecular triple helix. AFM detected disruption of collagen fibrils in the forms of reduced topographical surface thickness and the induction of ~30- to 100-nm voids in the collagen fibril matrix for mechanically tested samples. Second harmonic imaging microscopy detected the induction of ~10- to 100-µm regions where the noncentrosymmetric structure of collagen had been disrupted. These mechanically induced changes, ranging from molecular to microscale disruption of normal collagen structure, represent a previously unreported aspect of tissue fatigue damage in noncontact ACL failure. Confirmatory evidence came from the explants of 5 patients undergoing ACL reconstruction, which exhibited the same pattern of molecular, nanoscale, and microscale structural damage detected in the mechanically tested cadaveric samples.

CONCLUSION

The authors found evidence of accumulated damage to collagen fibrils and fibers at the ACL femoral enthesis at the time of surgery for noncontact ACL failure. This tissue damage was similar to that found in donor knees subjected in vitro to repetitive 4 times-body weight impulsive 3-dimensional loading known to cause a fatigue failure of the ACL.

CLINICAL RELEVANCE

These findings suggest that some ACL injuries may be due to an exacerbation of preexisting hierarchical tissue damage from activities known to place larger-than-normal loads on the ACL. Too rapid an increase in these activities could cause ACL tissue damage to accumulate across length scales, thereby affecting ACL structural integrity before it has time to repair. Prevention necessitates an understanding of how ACL loading magnitude and frequency are anabolic, neutral, or catabolic to the ligament.

Character comparison of abdomen-derived and eyelid-derived mesenchymal stem cells

OBJECTIVES

While most human adipose tissues, such as those located in the abdomen, hip and thigh, are of mesodermal origin, adipose tissues located in the face are of ectodermal origin. The present study has compared stem cell-related features of abdomen-derived adult stem cells (A-ASCs) with those of eyelid-derived adult stem cells (E-ASCs).

MATERIALS AND METHODS

Adipose tissue-derived cells were maintained in DMEM supplemented with 10% FBS. Before passage 6, cells were analysed using FACS, immunocytochemistry and quantitative real time PCR (qRT-PCR). To examine multi-differentiational potential, early passage ASCs were cultivated in each of a commercial Stempro(®) Differentiation kit.

RESULTS

Unlike fibroblast-like morphology of A-ASCs, E-ASCs had bipolar morphology. Both types of cell exhibited similar surface antigens, and neuronal cell-related genes and proteins. However, there were differences in mRNA expression levels of CD90 and CD146; neuron-specific enolase (NSE) and nuclear receptor-related protein 1 (Nurr1) were different between the two cell types. There was no difference in multi-differentiational potential between 3 E-ASCs lines, however, E-ASCs had higher expression levels of chondrocyte-related genes compared to A-ASCs. These cells underwent senescence and maintained normal karyotypes.

CONCLUSIONS

Although isolated from similar adipose tissues, both types of cells displayed many contrasting characteristics. Understanding defining phenotypes of such cells is useful for making suitable choices in differing clinical indications.

Human insulin secreted from insulinogenic xenograft restores normoglycemia in type 1 diabetic mice without immunosuppression

In the present study, we examined the therapeutic potential of human amnion-derived insulin-secreting cells for type 1 diabetes. Human amniotic mesenchymal stem cells (hAMs) were isolated from amnion and cultivated to differentiate into insulin-secreting cells in vitro. After culture in vitro, the differentiated cells (hAM-ISCs) were intensively stained with dithizone and secreted insulin and c-peptide in a high-glucose-dependent manner. They expressed mRNAs of pancreatic cell-related genes, including INS, PDX1, Nkx6-1, NEUROG3, ISL1, NEUROD1, GLUT1, GLUT2, PC1/3, PC2, GCK, PPY, SST, and GC, and were positive for human insulin and c-peptide. Transplantation of hAM-ISCs into the kidneys of mice with streptozotocin-induced diabetes restored body weight and normalized the blood glucose levels, which lasted for 210 days. Only human insulin and c-peptide were detected in the blood of normalized mice after 2 months of transplantation, but little mouse insulin and c-peptide. Removal of graft-bearing kidneys from these mice resulted in causing hyperglycemia again. Human cell-specific gene, hAlu, and human pancreatic cell-specific genes, insulin, PDX1, GLUT1, GLP1R, Nkx6-1, NEUROD1, and NEUROG3, were detected in the graft-bearing kidneys. Colocalization of human insulin and human nuclei antigen was also observed. These results demonstrate that hAMs could differentiate into functional insulin-secreting cells in vitro, and human insulin secreted from hAM-ISCs following transplantation into type 1 diabetic mice could normalize hyperglycemia, overcoming immune rejection for a long period.

Manganese does not alter the severe neurotoxicity of MPTP

We utilized a mice model of Parkinsonism: (1) to evaluate 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity; and (2) to evaluate whether manganese (Mn) exposure can affect MPTP-induced neurotoxicity. A 2 x 3 experimental design (MPTP x+/- Mn) was as follows: SS, MPTP(-) x Mn(-); SLMn, MPTP(-) x low Mn(+); SHMn, MPTP(-) x high Mn(+); MpS, MPTP(+) x Mn(-); MpLMn, MPTP(+) x low Mn(+); MpHMn, MPTP(+) x high Mn(+). We administered MPTP (30 mg/kg per day) to male C57BL/6 mice intraperitoneally, once a day for 5 days. Subsequently, mice were treated with either 2 or 8 mg/kg of MnCl(2).4H(2)O intraperitoneally, once a day for 3 weeks. Blood and striatal Mn levels were elevated in the Mnexposed groups. The number of tyrosine hydroxylase (TH)-immunoreactive (ir) neurons in the substantia nigra pars compacta were decreased significantly in the MPTP-exposed groups. The densities of TH-ir axon terminals in caudate-putamen (CPU) were significantly decreased in the MPTP-treated groups. However, Mn treatment did not affect MPTP neurotoxicity. The densities of glial fibrillary acidic protein (GFAP)-ir astrocytes in the CPU or globus pallidus were significantly increased in the MPTP-treated groups. Concentrations of dopamine in the striatum were decreased significantly in the MPTP-exposed groups only, but Mn had no effect.

Gross quantitative measurements of spinal cord segments in human

STUDY DESIGN

Anatomical measurement.

OBJECTIVE

To obtain quantitative anatomical data on each spinal cord segment in human, and determine the presence of correlations between the measures.

SETTING

Department of Rehabilitation Medicine, Pusan National University Hospital, Pusan, Korea.

METHODS

A total of 15 embalmed Korean adult human cadavers (13 males, two females; mean age 57.3 years) were used. The length of each cord segment was defined as the root attachment length plus the upper inter-root length. After performing a total vertebrectomy, a transverse cut was made at the approximate proximal and distal point of each segment from segment C3 to S5. Sagittal and transverse diameters at the proximal end of each segment, and cross-sectional area, height, and volume of the segment were measured.

RESULTS

The transverse diameter was largest at segment C5, and decreased progressively to segment T8. However, the sagittal diameter of each segment did not change distinctly with the segment. The cervical and lumbar enlargements were determined by the transverse diameters of the segments. Segment C5 had the largest cross-sectional area, at 75.0 mm(2). Segment T6 was the longest, averaging 22.4 mm in length. The longest segment in the cervical spinal cord was segment C5, at 15.5 mm, and segment L1 in the lumbar spinal cord. The volume was largest at segment C5, with a value of 1173.9 mm(3).

CONCLUSIONS

We found characteristic quantitative differences in the values of the parameters measured in the thoracic spinal cord compared to those measured in the cervical and lumbar or lumbosacral spinal cords. These measurements of spinal cord segments appear to provide valuable and practical standard quantitative features and may provide basic data for understanding the morphometric characteristics relevant to pathophysiologic conditions of the spinal cord.

Immunohistochemical characterization of macrophage and dendritic cell subpopulations of the spleen, thymus, tongue and heart in cyclophosphamide-induced immunosuppressed rat

This study was undertaken to investigate the immunohistochemical characterization of different subpopulations of macrophages and dendritic cells (DCs) of the spleen, thymus, tongue and heart in cyclophosphamide (CY)-induced immunosuppressed rat. After CY treatment, remarkably, ED1+, ED2+ and ED3+ macrophage subpopulations, in general exhibited signs of cellular activation such as an increase in number and size of cell, and an upregulation of the ED1, ED2 and ED3 reactive surface molecule expression in all the organs studied, except for some macrophage subpopulations including ED1+ macrophages in the non-lymphoid tissues. Subpopulations of DCs showed a differential sensitivity to CY. Lymphoid DCs were more sensitive to CY than non-lymphoid interstitial DCs. CY induced a conspicuous upregulation of intercellular adhesion molecule-1 (ICAM-1) expression in the vascular endothelial cells, splenic marginal zone and thymic cortex. In this study, we demonstrated the in vivo effects of CY treatment on subpopulations of macrophages and DCs as well as on ICAM-1 expression in the rat spleen, thymus, tongue and heart. Moreover, our results shed more light on the activation effects of CY on certain subpopulations of macrophages, on the differential sensitivity of DCs to CY between the immature and mature ones, on the functional role of different subpopulations of macrophages, and on the significance of upregulated ICAM-1 expression in the splenic marginal zone and thymic cortex after CY treatment.

Antitumor effect of intratumoral administration of dendritic cell combination with vincristine chemotherapy in a murine fibrosarcoma model

A new antitumor therapeutic strategy utilizing the combined effect of chemotherapy and DC (dendritic cell)-based immunotherapy was designed, and the effect of intratumoral injections of unpulsed, immature DCs was evaluated after in vivo pretreatment of vincristine on tumor growth in a murine fibrosarcoma tumor model. Vincristine exerted a much more potent apoptosis/necrosis-inducing effect on MCA-102 tumor cells than on DCs both in vitro and in vivo. Moreover, CD11c, CD40, CD80 and CD86 molecules on DCs were not downregulated after treatment with vincristine either in vitro or in vivo. The growth of tumor significantly regressed in the group which received the combined vincristine chemotherapy with intratumoral administration of DCs in contrast to the untreated group, the group treated with DCs alone, and the group treated with vincristine alone. In particular, an upregulated expression of CD40, CD80 and CD86 molecules on DCs was found in the combination treatment group. Furthermore, the number of CD4+ and CD8+ T cells and the staining intensity of their CD4 and CD8 surface molecules also increased after the combination treatment. Therefore, our results indicate the feasibility of this combination therapy with vincristine chemotherapy and DC-based immunotherapy as an efficient antitumor strategy for the treatment of fibrosarcoma.

Analysis of the in vivo dendritic cell response to the bacterial superantigen staphylococcal enterotoxin B in the mouse spleen

To investigate the in vivo effects of Staphylococcal enterotoxin B (SEB) on dendritic cells (DCs) in the spleen, a single dose of SEB (50 microg/kg) was administered to BALB/c mice by intraperitoneal injection. Afterwards, the mice were sacrificed at 2, 6 and 24 hr, 2, 4, 7 and 15 days, and the spleens were removed. The immunocytochemical characterization of the cells was carried out using various monoclonal antibodies in cryostat-cut sections. The distribution patterns of DCs and their major costimulatory molecules, CD80, CD86 and CD40 in the spleen were identified, and the evidence for maturation of DCs in vivo in response to SEB was obtained. It was found that systemic administration of SEB induced the migration of most of the immature, splenic DCs from the marginal zone to the periarterial lymphatic sheath within 6 hr. This movement paralleled a maturation process, as assessed by upregulation of CD40, CD80 and CD86 expression in the interdigitating dendritic cells (IDCs). The upregulation of costimulatory molecule expression was conspicuous only in DCs in contrast to other antigen-presenting cells (APCs) such as macrophages and B cells which did not show any significant alterations in their costimulatory molecule expression. We also demonstrated the temporal expression pattern of these costimulatory molecules on the activated DCs. The upregulation of costimulatory molecules on DCs reached a peak level 6 hr after SEB injection, while the increase in number of T cells expressing T cell receptor V138 reached a peak level on day 2 after SEB treatment. In conclusion, we demonstrated the in vivo DC response to SEB in the mouse spleen, especially a potent stimulative effect of SEB on DCs in vivo, a temporal distribution pattern of DCs as well as T cells including TCR Vbeta8+ T cells, and a differential expression pattern of costimulatory molecules on the activated DCs. The results of the present study indicate that DCs are the principal type of APCs which mediate T cell activation by SAg in vivo, and that each costimulatory molecule may have different role in the activation of DCs by SAg. Thus, it is plausible to speculate that DCs play a critical role in the T cell clonal expansion by SAgs and other SAg-induced immune responses in vivo.

Two-dimensional multiplanar and three-dimensional volume-rendered vascular CT in pancreatic carcinoma: interobserver agreement and comparison with standard helical techniques

OBJECTIVE

The purpose of this study was to compare two-dimensional curved multiplanar and three-dimensional reconstructions, routine axial presentations, and combined techniques in the assessment of vascular involvement by pancreatic malignancy.

MATERIALS AND METHODS

For 44 patients with known pancreatic malignancy a total of 56 arterial phase helical CT scans were obtained. Targeted pancreatic imaging was performed, and reformatted images were generated. Axial source images, reformatted images, and the combination of axial and reformatted images were interpreted independently by three observers. The observers graded the celiac axis, common and proper hepatic, splenic, gastroduodenal, and superior mesenteric arteries for tumor involvement. Grades of vascular involvement were compared by intra- and interobserver variability analyses.

RESULTS

Intraobserver agreement averaged over five vessels was good between the axial and combined techniques for each individual observer (0.64 < or kappa < or = 0.66), but intraobserver agreement was poor between the axial and reformatted (kappa = 0.17 and kappa = 0.31, respectively) and the reformatted and combined techniques (kappa = 0.31 and kappa = 0.38, respectively) for two observers. For grading of vascular involvement in each vessel, intraobserver agreement was good to excellent between the axial and combined techniques (0.48 or = kappa < or = 0.82). Interobserver agreement averaged over five vessels was poor for imaging techniques except between observer 2 and observer 3 on the axial (kappa = 0.47) and combined techniques (kappa = 0.47). For grading of vascular involvement in each vessel, interobserver agreement for reformatted technique was poor (0.09 < or = kappa < or = 0.40).

CONCLUSION

Multiplanar and volume-rendered techniques showed the highest intra- and interobserver variability in grading vascular involvement by pancreatic malignancy. These images should be used in combination with routine axial images to decrease observer variability.

US and CT findings of tuberculosis of the thyroid: three case reports

With two ultrasonographic and two CT films of three cases of thyroid tuberculosis, we evaluate the ultrasonographic and CT findings and correlate them with the pathologic findings. They are demonstrated as heterogeneous hypoechoic mass on ultrasonogram and peripheral-enhancing low-density abscess on CT scan with regional lymphadenopathy. Ultrasonography (US) and CT can help the diagnosis of thyroid tuberculosis.

Usefulness of T1-weighted image with fast inversion recovery technique in intracranial lesions: comparison with T1-weighted spin echo image

To evaluate the usefulness of T1-weighted images using the fast inversion recovery (T1FIR) technique as compared with routine T1-weighted spin echo (T1SE) images in various intracranial lesions. Routine spin echo and T1FIR images were performed in 15 consecutive patients with 18 lesions, cerebral infarction in five, astrocytoma in four, vascular lesion in three, encephalomalacia and hemorrhage in each two, arachnoid cyst and meningioma in each one. T1FIR images were performed with 1.5-T Signa [repetition time (TR)/echo time (TE)/inversion time (TI) was 2000/34/800 in 14, 4000/34/1200 in four lesions] and qualitatively compared with the T1SE images in signal intensity, lesion detectability, determination of lesion extent and conspicuity, contrast between lesion and background. Additionally, gray-to-white matter and cerebrospinal fluid (CSF)-to-white matter contrast were evaluated. The signal intensity of the lesions was similar on both T1FIR and T1SE images in all cases. The lesion detectability was similar on both sequences in 15 lesions, and the determination of the lesion extent was definitely higher in 16 lesions on the T1FIR images. Lesion conspicuity was superior in 11, similar in 5, and inferior in 2 patients on the T1FIR images. And also, contrast of lesion-to-background, gray-to-white matter, and CSF-to-white matter was superior on the T1FIR images. The T1FIR technique improved the determination of lesion extent and lesion conspicuity and was qualitatively superior for image contrast as compared with T1SE, but it takes more time than T1SE. The clinical application of T1FIR images depends on whether the superior aspect of the T1FIR images outweighs the disadvantage of the longer time required for this technique.

Proliferation of human Schwann cells induced by neu differentiation factor isoforms

Neu differentiation factor (NDF), a 44-kD polypeptide, is a member of the neuregulin family which also includes glial growth factor, heregulin and acetylcholine-receptor-inducing activity. Previous studies have demonstrated that NDF/glial growth factor/heregulin/acetylcholine-receptor-including activity are products of neurons and mediate proliferation, differentiation and gene expression in Schwann cells of experimental animals. In the present study, the efficacy of different isoforms of NDF in stimulating human Schwann cell proliferation is investigated in Schwann-cell-enriched cultures derived from fetal human dorsal root ganglia (15-20 weeks gestation). NDF isoforms examined include alpha1, alpha2, EGF-like domain alpha2 (EGFalpha2), alpha3, beta1, EGFbeta1, EGFbeta, beta2 and beta3. For the assessment of Schwann cell proliferation, double immunostaining using antibodies specific for S-100 protein and bromodeoxyuridine was used. While treatment of Schwann cells with NDF alpha isoforms (alpha1, alpha2, alpha3 and EGFalpha2) had little effect on Schwann cell proliferation, NDF beta isoforms (beta1, beta2, beta3, EGFbeta1 and EGFbeta) induced a greatly enhanced proliferation in Schwann cells. The proliferation index in unstimulated Schwann cells was 1.3 +/- 0.9%, whereas in Schwann cells treated with NDFbeta isoforms the proliferation index was 21.8 +/- 2.2%. The finding that the truncated beta isoforms such as EGFbeta1 and EGFbeta retain a mitogenic activity as potent as full-length beta isoform indicates that the C-terminal portion of the EGF-like domain is responsible for its receptor binding and subsequent biological activity.

Serum immunoreactivity to S-100 in children with cerebral palsy and delayed development and in their healthy parents

The passive immunization of pregnant female rats to S-100 protein often leads to ultra-structural abnormalities in the brain glial structures of the offspring of these rats and induces signs of delayed development in the fetal brain. Additionally passive immunization of pregnant animals with certain antigens induces permanent Ag-specific changes in the immune response of their offspring. The purpose of this study was to investigate serum immunoreactiviy (SIR) to S-100 in cerebral-palsied and developmentally-delayed children as well as in their healthy parents and to evaluate its significance related to radiologic findings of brain MRI and single photon emission computed tomography (SPECT). The subjects were children with cerebral palsy and delayed development that had abnormal findings on brain MRI or Brain SPECT. SIR to S-100 protein was measured by ELISA method in the patients, their healthy parents, 20 normal adult controls and 22 normally developed children. The SIR to S-100 protein was significantly higher in the cerebral-palsied and developmentally-delayed children when compared to that of the normal control group children. Increased SIRs were detected in healthy mothers but not in their fathers. There was no difference of SIR between the cerebral-palsied and developmentally-delayed children or any significant difference of SIRs according to the findings of the brain MRI or to developmental quotients. But, the SIRs to S-100 protein were higher in the group of more abnormal findings on brain SPECT.

Incidence and characterization of Listeria monocytogenes from domestic and imported foods in Korea

A total of 1,537 domestic and imported food products were examined for the incidence of Listeria monocytogenes between 1993 and 1997 in Korea. L. monocytogenes was detected using the U.S. Department of Agriculture isolation method. Isolated L. monocytogenes was confirmed by polymerase chain reaction with hly1 and hly2 primers designed from the listeriolysin O. Overall, 122 samples (7.9%) contained L. monocytogenes. The rate of isolation was 4.3% for beef, 19.1% for pork, 30.2% for chicken, 1.2% for shellfish, 4.4% for raw milk, 4.4% for frozen smoked mussels, and 6.1% for ice cream. No L. monocytogenes was found in pasteurized milk, pasteurized processed cheese, saltwater fish, dried seafoods, or ham. The overall incidence was lower than that reported in previous studies from other countries. Most isolates were serotype 1/2b except for chicken, in which serotype 1/2a was predominant. The serotyping results might imply the presence of food or geography-specific L. monocytogenes strains.

Pancreatic serous cystadenoma associated with islet cell tumour

We report the case of a 29-year-old female patient with a diffuse type of serous cystadenoma involving the entire pancreas except for part of the head, which was replaced by islet cell tumour. Ultrasound and CT showed multiple cysts in the entire pancreas and a solid mass with calcification in the head. MRI characterized the fluid content of the cysts and the extent of disease.

Value of the dynamic and delayed MR sequence with Gd-DTPA in the T-staging of stomach cancer: correlation with the histopathology

BACKGROUND

To evaluate the usefulness of dynamic and delayed magnetic resonance (MR) imaging in the T-staging of stomach cancer and to compare the enhancement pattern of the cancerous lesion and the normal wall.

METHODS

We performed MR imaging in 46 patients with stomach cancer (including four early gastric cancers and 42 advanced gastric cancers). Axial, sagittal, or coronal two-dimensional fast low-angle shot) MR images for the water-distended stomach were obtained with dynamic protocol, including precontrast images and images obtained 30, 60, 90, and 240-300 s after intravenous injection of the 0.1 mM Gd-DTPA/kg solution. We evaluated the thickness, interruption (or not) of the low signal intensity bands, and enhancement pattern of the cancerous wall and normal gastric wall. We prospectively evaluated the depth of cancer invasion, perigastric infiltration (extraserosal invasion), perigastric organ invasion, and regional lymph nodes and determined tumor staging on MR images. These MR evaluations including MR-determined staging were correlated with the surgicopathologic findings.

RESULTS

Stomach cancer was shown as having a thickened wall with a rapid enhancing pattern after intravenous Gd-DTPA administration. The mucosa (and/or submucosa) affected by stomach cancer showed an early enhancement pattern (30-90 s after Gd-DTPA administration) in 43 of 46 patients (93%). The normal gastric mucosa demonstrated a delayed peak enhancement pattern (> 90 s after Gd-DTPA administration) in 29 of 46 patients (63%) and variable enhancement pattern in 17 of 46 patients (37%). An interrupted low signal intensity band or highly enhanced tumorous lesion penetrating through the gastric wall was seen in 17 of 19 pT3 patients (90%). Consistency between MR-determined staging and surgicopathologic staging occurred in three of four pT1 tumors (75%), 10 of 13 pT2 tumors (77%), 17 of 19 pT3 tumors (90%), and eight of 10 pT4 tumors (80%); overall accuracy was 83%. Overall accuracy of regional lymph node involvement, as determined by enhanced MR, was 52%; 24 of 46 node groups were positive.

CONCLUSIONS

Dynamic and delayed MR imaging can be useful for predicting depth of cancer invasion, perigastric infiltration (extraserosal invasion), and perigastric organ invasion by gastric cancer.

Significance of resistive index in color Doppler ultrasonogram: differentiation between benign and malignant breast masses

The objective of this article is to evaluate the significance of resistive index in differentiation between benign and malignant breast lesions on duplex ultrasonographic examination. Resistive indices obtained in 106 breast lesions of 104 patients were included. Sixty-four were benign (mean age: 32.4 +/- 11.1 years), and 42 were malignant lesions (mean age: 47.8 +/- 11.4 years). The resistive index was classified as follows: below 0.49, from 0.5 to 0.59, 0.6 to 0.69, 0.7 to 0.79, and above 0.8. We analyzed and defined the optimal threshold value of RI between benign and malignant lesions. The mean values of the RI of benign and malignant lesions were 0.62 +/- 0.095 (range 0.44-0.86) and 0.74 +/- 0.097 (range, 0.50-0.92), respectively. The resistive index exceeded 0.7 in 80% of malignant lesions. The difference of the RI between malignant and benign lesions was statistically significant when the threshold value was 0.7 (P < 0.001). A resistive index over 0.7 may suggest malignant lesions. Due to the considerable overlap of the range of the RI, it may not be diagnostic in any single patient; however, it may be helpful in conjunct with gray-scale image.

The structural basis for DNA binding by an anti-DNA autoantibody

We have used single and multiple site-directed mutagenesis, and molecular modeling, to identify critical residues in the DNA binding site of MAb 2C10, an IgG anti-dsDNA autoantibody from an MRL/lpr lupus mouse. Simultaneous replacement of four Arg residues in the CDR3H abolished binding activity. With one exception, replacement of any one of these Arg residues reduced the activity to 20-50% of the unmutated scFv activity. Arg to Asp replacements had a slightly greater effect than Arg to Ala replacements. In the one exceptional case, replacement of Arg99 with Ala actually increased DNA binding five-fold and replacement by Asp had little effect. Mutation of Phe32 and Asn35 to A1a in CDRIH decreased DNA binding, whereas replacement of Arg31 with A1a had negligible effect. Ala substitution of any one of a cluster of Asp residues in CDR1L increased DNA binding three to six-fold, confirming previous findings that the L-chain of MAb 2C10 is not favorable for DNA binding. The L-chain does participate in shaping the selectivity of antigen binding, and mutation of CDR3L residue Asp92 or Asn93 caused a decrease in DNA binding activity. Directed mutagenesis, consistent with a molecular model, indicates that: several CDR amino acids contribute to DNA binding, without one residue dominating; both VH and VL CDR3 domains contribute to specificity of binding whereas the CDR1L hinders DNA binding. The results suggest a significant role for electrostatics in the interaction of DNA with MAb 2C10.

Post-traumatic arterial priapism: colour Doppler examination and superselective arterial embolization

PURPOSE

To evaluate selective embolization for management of post-traumatic priapism and colour Doppler sonography for the diagnosis of the causative lesion and for planning embolization.

MATERIALS AND METHODS

Six male patients with post-traumatic priapism underwent selective angiography and embolization. Colour Doppler sonography with grey-scale was performed in all six patients before angiography.

RESULTS

Selective angiography showed intracavernosal arteriovenous fistulas in all patients and pseudoaneurysm of the cavernosal artery (or common penile artery) in three patients. After successful embolization, detumescence was achieved in all patients. Colour Doppler sonography enabled localization and characterization of the lesion causing priapism in four patients. Grey-scale ultrasonography showed the dilated cavernosal sinuses in all patients.

CONCLUSION

Angiography with selective embolization is safe and effective method to correct post-traumatic priapism. Colour Doppler sonography with grey scale is a useful preangiographic study, as it allows for characterization and localization of the causative lesion except lesions at the proximal cavernosal or distal penile artery near the symphysis pubis.

Hepatic involvement in hypereosinophilic syndrome: value of portal venous phase imaging

US, portal venous phase CT, and MRI-CSE (MRI with conventional spin-echo sequence) findings in three cases of hepatic involvement in hypereosinophilic syndrome are presented. These showed varied imaging findings, but portal venous phase CT showed multiple, poorly marginated, and hypodense hepatic lesions in all three cases. The result suggested that portal venous phase CT is the optimal method for depicting hepatic involvement.

Bilateral primary renal non-Hodgkin's lymphoma presenting with acute renal failure: successful treatment with systemic chemotherapy

Primary renal non-Hodgkin's lymphoma (NHL) with acute renal failure is a very rare condition, which frequently occurs in bilateral renal involvement. We report a 26-year-old male with primary bilateral renal NHL presenting with acute renal failure. A CT scan of the abdomen showed markedly enlarged kidneys with multinodularity and para-aortic lymphadenopathy. A percutaneous renal biopsy demonstrated 'follicular center lymphoma, diffuse, small cell'. Thirteen cycles of systemic chemotherapy with cyclophosphamide-doxorubicin-vincristine-prednisolone (CHOP) and ifosfamide-methotrexate-etoposide-bleomycin (IMVP-Bleo) regimens were administered, which resulted in normalization of renal function with improvement of renal lymphoma. Since there was no further change of renal lesions after initial partial remission, a follow-up renal biopsy was performed 10 months after diagnosis, and no residual lymphoma was found.

Developmental expression of 'RZR beta, a putative nuclear-melatonin receptor' mRNA in the suprachiasmatic nucleus of the rat

RZR beta is a member of the retinoid Z receptor (RZR) family of orphan receptors, and its expression is brain-specific. Recently, it was reported that the distribution of RZR beta mRNA is partially coincident with melatonin binding sites and that RZR beta is a putative nuclear receptor of melatonin. Using in situ hybridization, we investigated the developmental expression of RZR beta mRNA in the suprachiasmatic nucleus (SCN) of the rat, which is considered as circadian pacemaker. The RZR beta mRNA was first found in the dorsomedial portion of the SCN at embryonic day 20, and RZR beta mRNA expression in the dorsomedial SCN continued until postnatal day 60. This result suggests that RZR beta plays specific roles as a transcription factor in the dorsomedial SCN but not in the ventrolateral SCN during development and throughout postnatal life.

Calcitonin gene-related peptide- and substance P-immunoreactive axons in the nucleus gracilis of the rat with special reference to axonal dystrophy: light and electron microscopic observations

Calcitonin gene-related peptide (CGRP) and substance P (SP)-immunoreactive (IR) axons in the nucleus gracilis of normal rats (1-15 months of age) were studied by light and electron microscopy. Besides many CGRP-IR and SP-IR varicosities with normal appearance, we found a few swollen (nearly round or oval) varicosities with either CGRP or SP immunoreactivity. Swollen CGRP-IR varicosities were more frequently seen than SP-IR ones, appearing from 3 months of age and increasing in number and size (up to approximately 25 microns in diameter) with advancing age. At the electron microscopic (EM) level, CGRP-IR and SP-IR swollen varicosities showed dystrophic changes, i.e., many membranous dense bodies, and proliferation of microtubules and neurofilaments. CGRP-IR or SP-IR dystrophic axons also contained many mitochondria and sometimes made synaptic contacts with nonreactive dendrites (occasionally with non-IR axons). These findings suggest that the dystrophic CGRP and SP axonal profiles represent a functionally distinct subpopulation of axonal dystrophy in the nucleus gracilis and use CGRP or SP as a neuroactive substance. Using a double-immunostaining method, many of normal CGRP-IR axons were identified to be SP-IR. However, no single dystrophic varicosity was found to contain both CGRP and SP immunoreactivities. These findings suggest that CGRP and SP afferents are independently affected and progress to dystrophic changes.

A case of rectal cancer with sternal metastasis as initial presentation

Colorectal cancer with bone metastasis as initial manifestation is a very rare event. We have reported a case of rectal cancer presenting with sternal metastasis. A 30 year-old man was evaluated due to pain in the sternal area with a bulging mass. History and physical examination did not suggest any specific disease. A radionuclide bone scan revealed increased uptake in the sternal area, right 6th rib, and sacrum. Microscopic examination of a biopsy specimen from the sternum showed metastatic adenocarcinoma. A barium enema and CT scan of the pelvis suggested carcinoma of the upper rectum. Adenocarcinoma of the rectosigmoid junction area was demonstrated by colonoscopic examination with biopsy. He received palliative transverse colostomy for obstruction without further treatment.

Peripheral cholangiocarcinoma: comparison of MRI with CT

To evaluate the clinical utility of computed tomography (CT) and magnetic resonance imaging (MRI) in the diagnosis of peripheral cholangiocarcinoma of the liver, 11 patients with pathologically proven peripheral cholangiocarcinoma were examined with both CT and MRI. On CT scans in 10 cases, the tumors appeared as irregular, low-attenuation masses with a wide variation in heterogeneity. Contrast enhancement of the tumors was mild in nine cases and moderate in one case, at the periphery. Tumor was not identified in one case. On T1-weighted MRIs, the tumors showed low intensity in eight cases and isointensity in three cases. On T2-weighted images, the tumors showed high intensity in all 11 cases. Focal dilatation of the intrahepatic bile ducts around the tumor was seen in one case on MRIs and in four cases on CT scans. Portal vein invasion of the tumors was seen in one case, and lymphadenopathy was seen in four cases on both MRIs and CT scans. MRI was slightly superior to CT in detecting the tumors, was inferior to CT in delineating focal ductal dilatation around the tumors, and was equal to CT in assessing extent of the tumors.

Krukenberg's tumor of the ovary: MR imaging features

OBJECTIVE

Krukenberg's tumors are metastatic tumors of the ovary. Some of these tumors had hypointense solid components on T2-weighted MR images. The purpose of this study was to evaluate the MR features of Krukenberg's tumors and to compare them with those of other solid ovarian tumors to determine whether hypointense solid components on MR images were characteristic of Krukenberg's tumors.

MATERIALS AND METHODS

Twelve patients with 21 surgically proven Krukenberg's tumors of the ovary were included in the study; the tumors were bilateral in nine and unilateral in three. The MR images were studied to determine the morphologic characteristics and signal intensity patterns of the tumors (especially the presence or absence of hypointense solid components on T2-weighted images and isointense components on T1-weighted images). MR findings were correlated with histopathologic results. The MR features of 26 additional benign or malignant solid primary ovarian tumors were reviewed for comparison.

RESULTS

Of the 21 Krukenberg's tumors, 14 were mostly solid and seven were entirely cystic or mostly cystic on MR images. All had sharp margins, and the oval configuration was preserved in 16. Twelve (57%) of the 21 tumors showed various amounts of hypointense solid components in random distribution or predominantly in the periphery on MR images; pathologically, these components corresponded to areas of dense collagenous stroma. MR imaging also showed that the cystic components within the masses had either well-defined or ill-defined borders. Multiseptation was noted in two masses. Of the 26 additional primary ovarian tumors, only three showed hypointense solid components on MR images. These included thecoma, fibrothecoma, and poorly differentiated adenocarcinoma.

CONCLUSION

Our findings suggest that identification of hypointense solid components within an ovarian mass on T2-weighted MR images is a characteristic, although not specific, finding for Krukenberg's tumors, especially when the tumors are bilateral, have sharp margins, and have an oval configuration.

Calcitonin gene-related peptide-like immunoreactive (CGRPI) elements in the circadian system of the mouse: an immunohistochemistry combined with retrograde transport study

This study was based on immunohistochemical detection of calcitonin gene-related peptide-like immunoreactive (CGRPI) neurons and fibers in the suprachiasmatic nucleus (SCN) and intergeniculate leaflet (IGL) of the mouse. CGRPI neurons and fibers were found within the ventrolateral part of the SCN, in the whole extent of IGL and sparsely distributed in ventral lateral geniculate body. The presence of CGRPI structures in the SCN and IGL of the mouse further supports the hypothesis of differences in the content of neuroactive substances in the circadian clock between mammalian species. Fluorogold retrograde transport combined with CGRP immunofluorescence demonstrates that CGRPI neurons in the IGL constitute a part of IGL reciprocal connections.

Profile of Fos-like immunoreactivity induction by light stimuli in the intergeniculate leaflet is different from that of the suprachiasmatic nucleus

Light stimuli induce Fos-like immunoreactivity (FLI) in suprachiasmatic nucleus (SCN) and intergeniculate leaflet (IGL). Short pulses of light stimuli that synchronize the circadian rhythms induce FLI in SCN. The characteristics of light induction of FLI in the IGL were studied using immunohistochemistry. In the IGL, at least 2 h of sustained light stimuli were necessary to show an increase of FLI. This FLI persisted while the light was turned on. FLI induction in the IGL by light stimuli was not circadian time specific response. These findings imply that the functional significance of Fos activation on circadian rhythms and mechanism of FLI induction in IGL would be different from that in SCN.

Therapeutic percutaneous aspiration of hepatic abscesses: effectiveness in 25 patients

OBJECTIVE

The objective of this study was to evaluate the effectiveness of sonographically guided needle aspiration and systemic antibiotic therapy for the treatment of hepatic abscesses.

SUBJECTS AND METHODS

From June 1989 to September 1991, sonographically guided needle aspiration and systemic antibiotics were used to treat 25 consecutive patients with 25 hepatic abscesses. Among 36 patients with hepatic abscesses who were admitted to the hospital during that time, six had antibiotic therapy only; of these, three had microabscesses, two had abscesses less than 3.0 cm in diameter, and one refused needle aspiration. Four patients had surgical external drainage (three had cholelithiasis in addition to hepatic abscesses, and one did not respond to needle aspiration). Two patients treated in 1989 had drainage via an indwelling catheter, which was the preferred method at that time. The remaining 24 patients and one patient who had needle aspiration followed by surgical drainage made up the study group. Seventeen of the hepatic abscesses were caused by pyogenic organisms, six by amoeba, and two by unknown organisms. Eighteen abscesses (72%) were aspirated once, four (16%) were aspirated twice in 8 days, two (8%) were aspirated three times in 14 days, and one (4%) was aspirated four times in 10 days. Persistent fever, pain and tenderness in the right upper quadrant, and leukocytosis were the indications for multiple aspirations. Follow-up sonography was performed to evaluate the outcome of treatment.

RESULTS

In 16 cases (64%), the abscesses disappeared within a mean of 84 days. In eight cases (32%) with only partial follow-up, the patients were asymptomatic at the time of discharge and the abscesses were markedly smaller on the last follow-up sonograms (mean, 43 days). One patient (4%) did not respond to aspiration and had surgical drainage. The length of hospitalization varied from 5 to 42 days (mean, 22 days). In patients who became afebrile during the treatment, the fever had lasted from 0 to 10 days (mean, 3 days). Only one patient had a complication of the procedure, a pleural effusion that was treated conservatively.

CONCLUSION

Our results show that sonographically guided needle aspiration combined with antibiotic therapy is effective as the initial treatment for hepatic abscesses.

Hepatic arterial color Doppler signals in Caroli's disease

Three siblings with congenital dilatation of the intrahepatic bile ducts (Caroli's disease) are presented. Bile duct pathology was associated with congenital hepatic fibrosis and polycystic renal disease in all three patients. On color Doppler imaging (CD imaging), multiple small color Doppler signals were observed in the vascular radicles within the dilated bile ducts or in the center of the lumen apart from the vascular radicles, as well as in other well-known sonographic findings such as bile duct dilatations and bilary calculi. Doppler frequency spectral analysis confirmed all these color signals as arterial in origin in all patients, revealing pulsatile wave patterns. In spite of the fact that portal venous radicles have been well described on conventional sonograms or computed tomography (CT), continuous wave patterns of venous flow on spectral analysis were not detected in all patients. Identification of such less emphasized arterial flow may add another clue in the diagnosis and pathogenesis of this rare disease entity. In conclusion, color Doppler signals of arterial wave pattern within the dilated bile ducts are another helpful diagnostic criteria in previously reported sonographic findings, and these color signals are easily depicted on sonograms with color mapping.

Distribution and origin of vasoactive intestinal polypeptide-like immunoreactive fibers in the central amygdaloid nucleus of the rat: an immunocytochemical analysis

We studied the distribution of vasoactive intestinal polypeptide-like immunoreactive (VIPLI) fibers in the central amygdaloid (AC) nucleus of the rat, using indirect immunofluorescence and the origins of such fibers using a combination of retrograde tracing with immunocytochemistry. VIPLI fibers formed a dense fiber plexus in the lateral subdivision of the AC nucleus, but other subdivisions showed little immunoreactivity. Destruction of the supramammillary (SuM) region and the adjacent lateral hypothalamus, both of which contained a group of VIPLI neurons, resulted in the marked reduction of VIPLI fibers in the ipsilateral AC nucleus, indicating that many of the fibers in the AC nucleus originate from these two areas. This assumption was supported by the finding that injection of fast blue dye into the AC nucleus labeled the VIPLI neurons in the SuM region and lateral hypothalamus.