Non-cystic Controls Research Articles

Interleukin-6 Modulates Action Potential Generation in Freshly Isolated Rat Dorsal Root Ganglia Neurons And its Stimulating Effect Is Exacerbated in Polycystic Kidney Disease

Our laboratory has demonstrated a central role for increased afferent nerve renal activity (ARNA) in the progression of cystogenesis in the PCK rat model of polycystic kidney disease (PKD). The underlying cause for the pathological increase in ARNA is unknown. Inflammatory cell infiltration and increased proinflammatory cytokine content, such as interleukin 6 (IL-6), have been reported in PKD. We hypothesized inflammatory cytokines directly increase sensory nerve activity, and this response is exacerbated in PKD. We measured action potential generation (AP) in freshly isolated dorsal root ganglion (DRG) neurons in PCK rats and non-cystic controls, and their response to IL-6. DRGs (T10-L1) were isolated from Sprague-Dawley (SD) or PCK rat (Age: 10-26 weeks) spinal cords, enzymatically digested and mechanically dissociated. Neurons were plated on coverslips, and AP were recorded within 24-hours (whole-cell patch-clamp). We tested the effects of IL-6 (0.04 μg/ml) and bradykinin (BK; 40μg/ml) on AP under 100, 200 pA, and 300 pA current clamp steps. IL-6 elicited either an excitatory response or inhibitory response in AP. In excitatory cells (EC), AP was normalized to BK peak response at +300 pA. In inhibited cells (IC), AP was normalized to baseline at +300 pA. PCK and IL-6 effects were assessed by two-way ANOVA (Bonferroni post hoc test;*p<.05); data as mean ± SEM. Proportion of ECs and ICs did not differ between SD and PCK rats. IL-6 increased AP at 300 pA from 0.48±0.28 (baseline) to 0.95±0.05 (p<.05) in SD ECs cells. BK further increased AP, showing no cell fatigue by IL-6 exposure. In PCK ECs, IL-6 increased AP at 100 pA (0.07±0.05 vs. 0.52±0.25), at 200 pA (0.47±0.27 vs. 1.39±0.81), and 300 pA (0.54±0.25 vs. 1.11±0.47). BK further increased AP at 100 pA to 0.70± 0.28 but decreased AP at 200 pA to 1.21±0.40 and at +300 pA to 1.00±0.00, indicating that neurons activity was likely plateaued by IL-6 at +200 and +300 pA. In both SD and PCK ICs, there was a main effect of IL-6 and BK treatment across all current steps (p<0.05). In SD ICs, IL-6 decreased AP at 200 pA (1.03±0.67 vs. 0.28±0.24) and 300 pA (1.00±0.00 vs. 0.28±0.24). BK had no effect at +200 pA and partially reversed the effect of IL-6 at +300 pA (AP increase to 0.53±0.27). In PCK ICs, IL-6 decreased AP at +200 pA (0.21±0.08 vs. 0.11±0.09) and +300 pA (1.00±0.00 vs. 0.42±0.24). BK increased AP at +200 pA (0.67±0.37) and +300 pA (0.71±0.33). These data partially support our hypothesis that IL-6 increases sensory nerve discharge. This effect was not observed uniformly across cells, as there were inhibitory and excitatory responses in both PCK and SD rats. We conclude that pro-inflammatory cytokine IL-6 can increase a subset of DRG neuron activity and responsiveness, an effect potentiated in PKD. This neuro-immune interaction might contribute to the underlying increase in ARNA and cystogenesis in PKD. Further experimentation is underway to test neuronal sensitivity to IL-6 and other inflammatory cytokines, as well as the posited potentiated effects in PKD. Supported in part by the PKD Foundation Research Award 1022534 (CB); NIDDK/PKD RRC Pilot and Feasibility Award U24DK126110 (CB). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Afferent Renal Nerve Activity is Proportionately Increased with Cystic Progression in a Preclinical Model of Autosomal Recessive Polycystic Kidney Disease

Polycystic kidney disease (PKD) is the most common genetic cause of kidney failure, though the mechanisms underlying cyst formation and disease progression remain unclear. Innervation of the kidney contributes to the pathology of other cardiorenal dysfunction, including hypertension and chronic kidney disease ‐ frequent complications of PKD. In previous studies, we demonstrated renal denervation (RDNX), either total or afferent‐targeted (sensory) nerve ablation, reduced cystogenesis in a rat model of autosomal recessive PKD, thus highlighting a role for renal afferent nerves in PKD renal cystogenesis. To further elucidate this novel relationship, we aimed to quantify the renal afferent nerve activity (ARNA) in the adult PCK rat compared to non‐cystic controls. We hypothesized that ARNA would be elevated in the PCK rat compared to controls, and ARNA would directly correlate with renal cystic severity.To address our hypothesis, we conducted direct afferent renal nerve recordings in 10‐week‐old PCK (n=15; 11M/4F) and age‐matched Sprague‐Dawley controls (SD; n=14; 6M/8F). Multiunit nerve recording was performed under isoflurane anesthesia by isolating and placing a renal nerve bundle on an iridium bipolar electrode, which was then encased in silicone. The nerve bundle was severed proximal to the electrode to isolate afferent renal nerve activity (ARNA). Following a 10‐minute stabilization period, resting ARNA was recorded for 10 minutes. To permit comparison between animals, resting ARNA was normalized to a maximal stimulus, achieved by renal pelvic perfusion of 50 µM capsaicin. Finally, electrical noise was isolated by sectioning the distal end of the nerve bundle. Recordings were rectified and integrated over 50 ms. ARNA was expressed as a percentage of maximal ARNA. Following nerve recording, kidneys were collected, formalin fixed, and embedded in paraffin for histologic analysis of renal cystic index (CI). Kidneys were stained with Masson’s Trichrome and analyzed using ImageJ, and CI was quantified by normalizing cystic area to the total kidney area. Data presented as mean ±SEM.Resting ARNA was higher in PCK (22.7±4.2%) rats compared to non‐cystic SD controls (7.4±1.3%; Figure 1). Overall, PCK rats had an average CI of 8.7±0.7%. No sex differences in ARNA between male and female PCK rats were detected; however, CI was higher in male PCK rats (9.5±2.3%) compared to female PCK (6.3±1.9%). Further analysis of ARNA versus cystic index revealed a direct correlation between ARNA and renal cystic severity (F=5.9; R=0.61; p<0.05; Figure 2).These findings support our hypothesis that ARNA is elevated in the PCK rat. Importantly, ARNA is directly correlated with cystic progression in this model. To our knowledge, this study is the first to directly measure ARNA in this model of ARPKD, as well as to compare ARNA to cyst severity. These findings, combined with our previous studies, lead us to conclude that increased ARNA may directly contribute to the progression of PKD in this model. Presently, these data are limited to single endpoint observations. We are currently conducting additional studies to further dissect the temporal relationship between ARNA and renal cyst development. Our future studies will investigate the stimuli amplifying ARNA in a continued effort to parse the role of this novel neural‐renal axis in the pathogenesis of PKD.

Contributions of afferent and sympathetic renal nerves to cystogenesis and arterial pressure regulation in a preclinical model of autosomal recessive polycystic kidney disease.

Polycystic kidney disease (PKD) is the most common inheritable cause of kidney failure, and the underlying mechanisms remain incompletely uncovered. Renal nerves contribute to hypertension and chronic kidney disease-frequent complications of PKD. There is limited evidence that renal nerves may contribute to cardiorenal dysfunction in PKD and no investigations of the role of sympathetic versus afferent nerves in PKD. Afferent renal nerve activity (ARNA) is elevated in models of renal disease and fibrosis. However, it remains unknown if this is true in PKD. We tested the hypothesis that ARNA is elevated in a preclinical model of autosomal recessive PKD and that targeted renal nerve ablation would attenuate cystogenesis and cardiorenal dysfunction. We tested this by performing total renal denervation (T-RDNx) or afferent renal denervation (A-RDNx) denervation in 4-wk-old male and female PCK rats and then quantified renal and cardiovascular responses 6 wk following treatment. Cystogenesis was attenuated with A-RDNx and T-RDNx versus sham controls, highlighting a crucial role for renal afferent nerves in cystogenesis. In contrast, blood pressure was improved with T-RDNx but not A-RDNx. Importantly, treatments produced similar results in both males and females. Direct renal afferent nerve recordings revealed that ARNA was twofold greater in PCK rats versus noncystic controls and was directly correlated with cystic severity. To our knowledge, we are the first to demonstrate that PCK rats have greater ARNA than noncystic, age-matched controls. The findings of this study support a novel and crucial role for renal afferent innervation in cystogenesis in the PCK rat.NEW & NOTEWORTHY This is the first study to dissect the contributions of renal sympathetic and afferent innervation in the PCK rat, a preclinical model of autosomal recessive polycystic kidney disease. We demonstrated that resting afferent renal nerve activity is greater in the PCK rat than noncystic controls and that basal afferent renal nerve activity is directly correlated with the extent of renal cystogenesis.

A Comprehensive Immune Cell Atlas of Cystic Kidney Disease Reveals the Involvement of Adaptive Immune Cells in Injury-Mediated Cyst Progression in Mice.

Inducible disruption of cilia-related genes in adult mice results in slowly progressive cystic disease, which can be greatly accelerated by renal injury. To identify in an unbiased manner modifier cells that may be influencing the differential rate of cyst growth in injured versus non-injured cilia mutant kidneys at a time of similar cyst severity, we generated a single-cell atlas of cystic kidney disease. We conducted RNA-seq on 79,355 cells from control mice and adult-induced conditional Ift88 mice (hereafter referred to as cilia mutant mice) that were harvested approximately 7 months post-induction or 8 weeks post 30-minute unilateral ischemia reperfusion injury. Analyses of single-cell RNA-seq data of CD45+ immune cells revealed that adaptive immune cells differed more in cluster composition, cell proportion, and gene expression than cells of myeloid origin when comparing cystic models with one another and with non-cystic controls. Surprisingly, genetic deletion of adaptive immune cells significantly reduced injury-accelerated cystic disease but had no effect on cyst growth in non-injured cilia mutant mice, independent of the rate of cyst growth or underlying genetic mutation. Using NicheNet, we identified a list of candidate cell types and ligands that were enriched in injured cilia mutant mice compared with aged cilia mutant mice and non-cystic controls that may be responsible for the observed dependence on adaptive immune cells during injury-accelerated cystic disease. Collectively, these data highlight the diversity of immune cell involvement in cystic kidney disease.

Outcomes of Fractionated Radiosurgery in Cystic Vestibular Schwannoma

Evaluate outcomes of fractionated SRS in predominantly cystic vestibular schwannoma. Patients undergoing fractionated Radiosurgery for VS were retrospectively reviewed. Patients with cystic tumors were considered candidates for SRS only if they did not have symptomatic or significant radiologic brainstem compression. VSs containing dominant intra-tumoral or peri-tumoral cyst(s) > 50% of the total tumor diameter by greatest linear axial CPA dimension, single or multicystic, were included for study. Pre-treatment clinical and radiographic features, including AAO-HNS hearing class, history of facial weakness, current facial and trigeminal nerve function, AAO-HNS tumor size, and intratumoral vs peritumoral cysts were captured. All Patients underwent treatment on C-Arm Linac with CBCT image guidance to a dose of 25gy/5#. Patients underwent MRI surveillance every 6 months for the first year, annually thereafter for the subsequent 2 years, and then every other year. 15 patients (12 women; median age at treatment, 53 years; range, 36-85 years) with cystic VS met inclusion criteria. The median radiologic follow-up within the cystic group was 48 months (range, 17-100 months), and the median change in tumor size was − 4.3mm. 12 tumors (80%) shrank, 2 (13%) remained stable (experienced significant cyst enlargement within 1 year after treatment, followed by spontaneous cyst shrinkage back to the original pretreatment size), and 1 patient (7%) experienced cyst enlargement of 9 mm over 21 months and underwent retrolabyrinthine subtotal tumor removal and cyst decompression enlarged. Tumor control rate in cystic group of 93%. The median radiologic follow-up in the non-cystic control group, comprising of 53 pts. was 67 months (range, 6-141 months), and the median change in size was −2.0 mm. Tumor control in the solid group was 94%. Comparing only those tumors that decreased in size showed that there was a trend toward a greater reduction within the cystic group, intratumoral being better than peri-tumoral cystic VSs (P = .05). The present study demonstrates that tumor control after fractionated SRS for dominant intratumoral cystic VS may not differ from that of noncystic VS in properly selected cases suggesting that intratumoral cysts have a different behavior compared with those with peripheral cystic components, latter may result from trapped arachnoid or a hemorrhage-related process making them, thus, more susceptible to growth despite control of the solid portion of the tumor.

Identification of housekeeping genes for microRNA expression analysis in kidney tissues of Pkd1 deficient mouse models

Polycystic kidney disease is a complex clinical entity which comprises a group of genetic diseases that leads to renal cyst development. We evaluated the most suitable housekeeping genes for microRNA expression by RT-qPCR analyses of kidney tissues in Pkd1-deficient mouse models from a panel of five candidates genes (miR-20a, miR-25, miR-26a, miR-191 and U6) and 3 target genes (miR-17, miR-21 and let-7a) using samples from kidneys of cystic mice (Pkd1flox/flox:Nestincre, CY), non-cystic controls (Pkd1flox/flox, NC), Pkd1-haploinsufficient (Pkd1+/−, HT), wild-type controls (Pkd1+/+, WT), severely cystic mice (Pkd1V/V, SC), wild-type controls (CO). The stability of the candidate genes was investigated using NormFinder, GeNorm, BestKeeper, DataAssist, and RefFinder software packages and the comparative ΔCt method. The analyses identified miR-26a as the most stable housekeeping gene for all kidney samples, miR-20a for CY and NC, miR-20a and miR-26a for HT and WT, and miR-25 and miR-26a for SC and CO. Expression of miR-21 was upregulated in SC compared to CO and trends of miR-21 upregulation and let-7a downregulation in CY and HT compared to its control kidneys, when normalized by different combinations of miR-20a, miR-25 and miR-26a. Our findings established miR-20a, miR-25, and miR-26a as the best housekeeping genes for miRNA expression analyses by RT-qPCR in kidney tissues of Pkd1-deficient mouse models.

Stereotactic Radiosurgery for Cystic Vestibular Schwannomas.

The optimum treatment for cystic vestibular schwannoma (VS) remains controversial. Anecdotally, many treating physicians feel that cystic VSs do not respond to stereotactic radiosurgery (SRS) as well as noncystic tumors. To present outcomes after treatment of predominantly cystic VS with SRS. A prospectively maintained clinical database of patients undergoing Gamma Knife (Elekta Instruments, Stockholm, Sweden) radiosurgery (GKRS) for VS at a single tertiary academic referral center was retrospectively reviewed. Patients diagnosed with cystic VS who were treated with GKRS between 1997 and 2014 were analyzed. Size-matched solid tumors treated with GKRS during this period were selected as controls. Twenty patients (12 women; median age at treatment, 56years; range, 36-85years) with cystic VS met inclusion criteria. The median radiologic follow-up within the cystic group was 63months (range, 17-201months), and the median change in tumor size was -4.9mm (range, -10.4 to 9.3mm). Sixteen tumors (80%) shrank, 2 (10%) remained stable, and 2 (10%) enlarged, accounting for a tumor control rate of 90%. The median radiologic follow-up in the noncystic control group was 67months (range, 6-141months), and the median change in size was -2.0mm (range, -10.4 to 2.5mm). Tumor control in the solid group was 90%. Comparing only those tumors that decreased in size showed that there was a trend toward a greater reduction within the cystic group ( P = .05). The present study demonstrates that tumor control after SRS for cystic VS may not differ from that of noncystic VS in selected cases.

Renal cyst growth is the main determinant for hypertension and concentrating deficit in Pkd1-deficient mice

We have bred a Pkd1 floxed allele with a nestin-Cre expressing line to generate cystic mice with preserved GFR to address the pathogenesis of complex ADPKD phenotypes. Hypertension affects about 60% of these patients before loss of renal function, leading to significant morbimortality. Cystic mice were hypertensive at 5 and 13 weeks of age, a phenotype not seen in non-cystic controls and Pkd1-haploinsufficient animals, which do not develop renal cysts. Fractional sodium excretion was reduced in cystic mice at these ages. Angiotensinogen gene expression was higher in cystic than non-cystic kidneys at 18 weeks, while ACE and the AT1 receptor were expressed in renal cyst epithelia. Cystic animals displayed increased renal cAMP, cell proliferation and apoptosis. At 24 weeks mean arterial pressure and fractional sodium excretion did not significantly differ between the cystic and non-cystic groups, whereas cardiac mass increased in cystic mice. Renal concentrating deficit is also an early finding in ADPKD. Maximum urine osmolality and urine nitrite excretion were reduced in 10–13 and 24-week-old cystic mice, deficits not found in haploinsufficient and non-cystic controls. A trend of higher plasma vasopressin was observed in cystic mice. Thus, cyst growth most probably plays a central role in early-stage ADPKD-associated hypertension, with activation of the intrarenal renin-angiotensin system as a key mechanism. Cyst expansion is also likely essential for the development of the concentrating deficit in this disease. Our findings are consistent with areas of reduced perfusion in the kidneys of patients with ADPKD.

Acceleration of the Meckel Syndrome by Near-Infrared Light Therapy

Background/Aims: Phototherapy using a narrow-band, near-infrared (NIR) light (using a light-emitting diode, LED) is being used to treat certain medical conditions. This narrow-band red light has been shown to stimulate cytochrome c oxidase (CCO) in mitochondria that would stimulate ATP production and has the ability to stimulate wound healing. LED treatment also decreases chemical-induced oxidative stress in tested systems. As renal cystic diseases are known to have evidence of oxidative stress with reduced antioxidant protection, we hypothesized that NIR light therapy might ameliorate the renal pathology in renal cystic disease. Methods: Wistar-Wpk/Wpk rats with Meckel syndrome (MKS) were treated with light therapy on days 10–18 at which time disease severity was evaluated. Wpk rats were either treated daily for 80 s with narrow-band red light (640–690 nm wavelength) or sham treated. At termination, renal and cerebral pathology was evaluated, and renal expression and activity of enzymes were assessed to evaluate oxidative stress. Blood was collected for blood urea nitrogen (BUN) determination, the left kidney frozen for biochemical evaluation, and the right kidney and head fixed for morphological evaluation. Results: There were no significant effects of LED treatment on body weight (BW) or total kidney weight in non-cystic rats. Total kidney weight was increased and anephric BW was decreased in cystic versus non-cystic controls. LED reduced BW and total kidney weight in cystic rats compared to non-light-treated cystic (control) rats. BUN was already increased almost 6-fold in cystic rats compared to control rats. BUN was further increased almost 2-fold with NIR treatment in both non-cystic and cystic rats compared to cystic and control rats. The hydrocephalus associated with Wpk/Wpk (ventricular volume expressed as total volume and as percent of anephric BW) was also more severe in NIR-treated cystic rats compared to the normal control rats. Renal glutathione peroxidase and catalase (CAT) were reduced in the cystic kidney while superoxide dismutase and CCO were increased. NIR increased CAT and CCO, marginally decreased glutathione S-transferase and slightly decreased glutathione reductase in cystic rats compared to the normal control rats. The detrimental effects of NIR may be related to reduced renal blood flow associated with progression of cystic pathology. Compression by cysts may not allow sufficient oxygen or nutrient supply necessary to support the increased oxidative phosphorylation-associated cellular activity, and the increased demand induced by NIR-increased CCO may have created further oxidative stress. Conclusion: LED phototherapy initiated after the onset of symptoms was detrimental to MKS-induced pathology. NIR stimulates CCO thereby increasing the kidney’s need for oxygen. We hypothesize that cystic compression of the vasculature impairs oxygen availability and the enhanced CCO activity produces more radicals, which are not sufficiently detoxified by the increased CAT activity.

Immunoreactive trypsin levels in neonates with meconium ileus

Serum immunoreactive trypsin (IRT) is used as a screening test for cystic fibrosis (CF) in neonates in many countries. Variations in IRT levels are observed in healthy and cystic neonates within the first few weeks of life. Fifteen percentage of CF neonates present with meconium ileus (MI). We hypothesised that there may be differences in serum IRT levels in cystic babies with simple and complicated MI. The aim of this study was to investigate the serum levels of IRT in neonates with CF presenting with MI. IRT levels were sequentially measured in neonates (n = 29) with CF with intestinal obstruction due to simple or complicated MI. These were compared to levels obtained from non-cystic neonates/controls admitted with a variety of other intra-abdominal pathologies (n = 49) IRT levels were significantly higher in the CF-MI group than the non-cystic controls (P < 0.001). There was no statistical difference in IRT levels between the simple or complicated MI groups. In the MI group there was no statistical difference between those who required operation, no difference between the pre- and post-operative IRT levels and no significant relationship between IRT levels and birth weight or gestation. Serum IRT levels are significantly elevated in neonates with CF and MI compared with non-cystic, non-MI neonates. The results of this observational study highlight that a single raised level of IRT in a neonate should prompt the analysis for CF regardless of any underlying surgical pathology.

Gender hormones and the progression of experimental polycystic kidney disease

Male gender is a risk factor for progression of autosomal-dominant polycystic kidney disease (ADPKD), clinically and in the Han:SPRD rat model. Orchiectomy limits progression, but mechanisms of the detrimental effect of androgen, and/or beneficial effects of estrogen, are not known. This protocol tested the hypothesis that male gender (intact androgen status) promotes progression, while female gender (intact estrogen status) is protective; and that these disease-modifying effects are due to changes in expression of known fibrotic mediators. Studies were performed in male and female noncystic control (+/+) and cystic (+/-) rats subjected to orchiectomy, ovariectomy, or sham operation. At 12 weeks of age, renal function was measured. Blood and kidneys were taken for measurement of plasma and renal renin, endothelin (ET-1), endothelial nitric oxide synthase (eNOS), and vascular endothelial growth factor (VEGF), using biochemical, protein expression, and immunohistochemical methods. Cystic male rats exhibited significantly reduced glomerular filtration (GFR) and effective renal plasma flow (ERPF) rates, with suppression of plasma and renal renin, up-regulation of renal ET-1 and eNOS, and down-regulation of renal VEGF expression. Orchiectomy attenuated the fall in GFR and ERPF, while numerically limiting changes in eNOS and VEGF. Female rats exhibited less cystic growth, with normal renin status, lesser elevation of renal ET-1, and proportionately lesser changes in VEGF and eNOS. Ovariectomy led to higher blood pressure and reduced GFR and ERPF, with a trend toward upregulation of ET-1, and significant down-regulation of VEGF and eNOS. Female gender is protective, but ovariectomy attenuates the protective effect of female gender, in association with changes in renal expression of ET-1, VEGF, and eNOS. The accelerated disease in male rats can be attenuated by orchiectomy and consequent changes in expression of disease mediators.

Kidney injury molecule-1 expression in murine polycystic kidney disease.

Kidney injury molecule-1 (Kim-1) is a type 1 membrane protein maximally upregulated in proliferating and dedifferentiated tubular cells after renal ischemia. Because epithelial dedifferentiation, proliferation, and local ischemia may play a role in the pathophysiology of autosomal dominant polycystic kidney disease, we investigated Kim-1 expression in a mouse model of this disease. In the Pkd2(WS25/-) mouse model for autosomal dominant polycystic kidney disease, cystic kidneys show markedly upregulated Kim-1 levels compared with noncystic control kidneys. Kim-1 is present in a subset of cysts of different sizes and segmental origins and in clusters of proximal tubules near cysts. Kim-1-expressing tubular cells show decreased complexity and quantity of basolateral staining for Na-K-ATPase. Other changes in polarity characteristic of ischemic injury are not present in Kim-1-expressing pericystic tubules. Polycystin-2 expression is preserved in Kim-1-expressing tubules. The interstitium surrounding Kim-1-expressing tubules shows high proliferative activity and staining for smooth muscle alpha-actin, characteristic of myofibroblasts. Although the functional role of the protein in cysts remains unknown, Kim-1 expression in tubules is strongly associated with partial dedifferentiation of epithelial cells and may play a role in the development of interstitial fibrosis.

Histopathology and growth pattern of cystic acoustic neuromas.

In a series of 571 acoustic neuromas, 23 were identified as cystic tumors. An immunohistochemical study including nervous system-associated protein (S-100), glial fibrillary acidic protein (GFAP), neurofilament protein (NF), laminin, fibronectin, vimentin, factor VIII (von Willebrand factor)-related antigen, and the nuclear antibody Ki-67 was performed. The cyst walls contained numerous S-100-positive fibrils distributed throughout the whole extent of the walls. Laminin, fibronectin, and vimentin were predominantly located around the vessel walls, factor VIII was found inside the vessels. GFAP-positive lamellae occurred in 50% of the cases near the surface of the cyst walls. Ki-67 is an antigen associated with cell proliferation. The density of Ki-67-positive cells was found to be 36 times lower in 16 noncystic controls than in the 23 cystic neuromas, indicating that the increase in tumor size in cystic acoustic neuromas may be caused by expansion of the cysts and not by an actual increase in the growth rate of the tumor cells. The data achieved in this series may contribute to better planning of the surgical approach. Because of the risk of sudden expansion of cystic elements, a wait-and-see policy should not be applied to patients with cystic acoustic neuromas.

Non-functional ovarian cysts do not affect ipsilateral or contralateral ovarian performance during in-vitro fertilization*

Reports on the significance of ovarian cystic structures during in-vitro fertilization (IVF) have been conflicting. This study examined the effect of such structures on ovarian performance during IVF. Twenty-one patients with one or more cystic structures of 20-50 mm in diameter, detected on day 6 of the menstrual cycle, were compared to 35 non-cystic controls. Differences (cyst versus non-cyst) included basal oestradiol (E2) levels (40 +/- 4.8 versus 29 +/- 2.0 pg/ml; P less than 0.01), ampoules of gonadotrophins administered (24 +/- 2 versus 16 +/- 1; P less than 0.001) and peak E2 concentrations (415 +/- 45 versus 744 +/- 88 pg/ml; P less than 0.05). There were no differences in the number of follicles aspirated or oocytes retrieved. In 19 patients with unilateral structures, the ipsilateral ovary produced fewer follicles (2.5 +/- 0.5 versus 3.9 +/- 0.6; P less than 0.05); however, there were no differences in the number or maturity of oocytes recovered. Since the numbers of oocytes recovered were equivalent in the presence or absence of ovarian cystic structures, their presence is not an indication to cancel an IVF cycle.